Dycor QuadLink Residual Gas Analyzer - irem senuhv.cheme.cmu.edu/manuals/residualgasanalyzerquadlink...viii | Dycor QuadLink Residual Gas Analyzer Electromagnetic Compatibility (EMC)

Dycor QuadLinkResidual Gas Analyzer

User Manual

Process Instruments150 Freeport Road

Pittsburgh, PA 15238PN 90290VE, Rev E

COMMITTED TO TOTAL QUALITY

QMT

ii | Dycor QuadLink Residual Gas Analyzer

© 2001 AMETEK

This manual is a guide for the use of the Dycor QuadLink Residual Gas Analyzer. Data herein has been verified and validated and is believedadequate for the intended use of this instrument. If the instrument or procedures are used for purposes over and above the capabilitiesspecified herein, confirmation of their validity and suitability should be obtained; otherwise, AMETEK does not guarantee results and assumesno obligation or liability. This publication is not a license to operate under, or a recommendation to infringe upon, any process patents.

AMETEK Process Instruments150 Freeport RoadPittsburgh, PA 15238, USAPhone: 412-828-9040Fax: 412-826-0399

AMETEK Process Instruments455 Corporate BoulevardNewark, Delaware 19702, USAPhone: 302-456-4400 (Main)

800-537-6044 (Service)800-222-6789 (Ordering)

Fax: 302-456-4444

AMETEK Process InstrumentsAMETEK-APIE OfficePostfach 2165D-40644 Meerbusch

ORRudolf-Diesel Strasse 16D-40670 MeerbuschGermanyPhone: 49-21-59-9136-0Fax: 49-21-59-9136-39

AMETEK Process Instruments7950 Whithorn DriveHouston, Texas 77095, USAPhone: 281-463-2820Fax: 281-463-2701

AMETEK Singapore PVT. Ltd.10 Ang Mo Kio Street 65#05-12 TechpointSingapore 569059Republic of SingaporePhone: 65-484-2388Fax: 65-481-6588

AMETEK Process InstrumentsWestern Research2876 Sunridge Way N.E.Calgary, AlbertaCanada T1Y 7H9Phone: 403-235-8400Fax: 403-248-3550

Offices

| iii

Table of Contents

Chapter 1 OVERVIEWDycor QuadLink Residual Gas Analyzer ...................................................... 1-1

QuadLink System ....................................................................................... 1-1Options for QuadLink System ................................................................. 1-2

Upgrading from Another Dycor Analyzer ................................................... 1-3Upgrading from an MA-Series Analyzer ............................................... 1-3Upgrading from an M-Series Analyzer .................................................. 1-3

Mass Spectrometer Theory.............................................................................. 1-4Mass Spectrometer Hardware .................................................................. 1-4

Ionization .............................................................................................. 1-5EI ionization ......................................................................................... 1-5Separation ............................................................................................. 1-5Detection ............................................................................................... 1-6

Data System ................................................................................................. 1-7Technical Support ............................................................................................. 1-8

Chapter 2 SPECIFICATIONS

Chapter 3 INSTALLATIONQuadLink System Mechanical Installation .................................................. 3-2

Check Sensor Filament. ............................................................................. 3-2Connect the Sensor to the Vacuum System .......................................... 3-3Connecting the Source to the Electronics ............................................. 3-4Connecting the Electrometer to the Power Supply ............................. 3-5Switching Between 110 and 220 Volts AC Line ..................................... 3-6Connect the Power Supply to the AC Line Power ............................... 3-7

Communications Setup ................................................................................... 3-8Connect QuadLink(s) to PC ..................................................................... 3-8

Single QuadLink connection (RS-232) ................................................ 3-8Networking multiple QuadLinks (RS-485) ......................................... 3-9

QuadLink LCD Display ................................................................................. 3-10Status ........................................................................................................... 3-10Messages ..................................................................................................... 3-10

Accessory Output ............................................................................................ 3-12Accessory Port Pinout .................................................................................... 3-13

iv | Dycor QuadLink Residual Gas Analyzer

Chapter 4 SERIAL COMMUNICATIONSCommunications Protocol ............................................................................... 4-1

Host Communications ............................................................................... 4-1Protocol......................................................................................................... 4-1

Error Codes ...................................................................................................... 4-16Bad Command .......................................................................................... 4-16Checksum .................................................................................................. 4-16Write-Only ................................................................................................. 4-16Out of Range ............................................................................................. 4-16Memory ...................................................................................................... 4-16Reset ............................................................................................................ 4-16Scan ............................................................................................................. 4-16

Operation .......................................................................................................... 4-17

Chapter 5 VACUUM AND PRESSURE REDUCTION SYSTEMSPumping System ............................................................................................... 5-2

Installation.................................................................................................... 5-2Pressure Reduction System ............................................................................. 5-4

Rack-Mount and Other Applications (M240)........................................ 5-7Atmospheric Pressure Sampling System ...................................................... 5-8

Chapter 6 MAINTENANCE AND TROUBLESHOOTINGQuadrupole Head Maintenance ..................................................................... 6-2Filaments ............................................................................................................. 6-2

Open Source ................................................................................................ 6-2Equipment required to replace a filament ........................................... 6-2Removing the QuadLink electrometer from the quadrupole head ...... 6-3Replacing the filament .......................................................................... 6-3Removing the old filament ................................................................... 6-3Installing the new filament .................................................................. 6-3Replacing the Source ............................................................................ 6-5

Disassembling the Open Source .............................................................. 6-5Assembly and installation of the open source ..................................... 6-5

Cleaning the open source ................................................................................ 6-7Mass filter ..................................................................................................... 6-7

Electron Multiplier / V-Stack Detector .......................................................... 6-8Troubleshooting the QuadLink ...................................................................... 6-9

Things to Check First ................................................................................. 6-9Quick and Easy Solutions ......................................................................... 6-9

Localizing the Problem................................................................................... 6-10Power Supply Communications ............................................................ 6-10Filament Trip/Overpressure and LEDs ................................................. 6-10RF Tune Error ............................................................................................ 6-11

| v

Chapter 7 SPARE PARTS, KITS AND ACCESSORIESStart-Up............................................................................................................... 7-1

Normal Operation ...................................................................................... 7-1Normal Maintenance ................................................................................. 7-1

Sensor Manifold Kits ........................................................................................ 7-2Spare Analyzer Heads ...................................................................................... 7-3

Open Sources .............................................................................................. 7-3Recommended Spare Parts List ...................................................................... 7-4QuadLink Accessories ...................................................................................... 7-6Pumping Systems .............................................................................................. 7-7

vi | Dycor QuadLink Residual Gas Analyzer

Safety Notes

WARNINGS, CAUTIONS, and NOTES contained in this manual emphasize critical instruc-tions as follows:

An operating procedure which, if not strictly observed, may result in personal injury orenvironmental contamination.

An operating procedure which, if not strictly observed, may result in damage to theequipment.

Important information that should not be overlooked.

Electrical Safety

Up to 2 kV may be present in the analyzer housings. Always shut down power source(s)before performing maintenance or troubleshooting. Only a qualified electrician should makeelectrical connections and ground checks.

Any use of the equipment in a manner not specified by the manufacturer may impair thesafety protection originally provided by the equipment.

Grounding

Instrument grounding is mandatory. Performance specifications and safety protection arevoid if instrument is operated from an improperly grounded power source.

Verify ground continuity of all equipment before applying power.

!NOTE

!CAUTION

!WARNING

!WARNING

| vii

PROTECTIVE CONDUCTOR TERMINAL

(BORNIER DE L’ECRAN DE PROTECTION)

Schutzerde

CAUTION - Risk of electric shock

(ATTENTION-RISQUE DE DÉCHARGE ÉLECTRIQUE)

Achtung - Hochspannung Lebensgefahr

CAUTION - (Refer to accompanying documents)

(ATTENTION-SE RÉFERER AUX DOCUMENTS JOINTS)

Achtung (Beachten Sie beiliegende Dokumente)

CAUTION - Hot Surface

(ATTENTION-SURFACE CHAUDE)

Achtung - Heiße Oberfläche

Warning Labels

These symbols may appear on the instrument in order to alert you of existing conditions.

viii | Dycor QuadLink Residual Gas Analyzer

Electromagnetic Compatibility (EMC)

Read and follow the recommendations in this section to avoid performance variationsor damage to the internal circuits of this equipment when installed in harsh electricalenvironments.

The various configurations of the LC Series should not produce, or fall victim to, electro-magnetic disturbances as specified in the European Unions EMC Directive. Strict compli-ance to the EMC Directive requires that certain installation techniques and wiring practicesare used to prevent or minimize erratic behavior of the Analyzer or its electronic neighbors.Below are examples of the techniques and wiring practices to be followed.

In meeting the EMC requirements , the various Analyzer configurations described in thismanual rely heavily on the use of metallic shielded cables used to connect to thecustomers equipment and power. Foil and braid shielded I/O and DC power cables arerecommended for use in otherwise unprotected situations. In addition, hard conduit,flexible conduit, and armor around non-shielded wiring also provides excellent control ofradio frequency disturbances. However, use of these shielding techniques is effective onlywhen the shielding element is connected to the equipment chassis/earth ground at bothends of the cable run. This may cause ground loop problems in some cases. These shouldbe treated on a case-by-case basis. Disconnecting one shield ground may not providesufficient protection depending on the electronic environment. Connecting one shieldground via a 0.1 microfarad ceramic capacitor is a technique allowing high frequencyshield bonding while avoiding the AC-ground metal connection. In the case of shieldedcables the drain wire or braid connection must be kept short. A two-inch connectiondistance between the shields end and the nearest grounded chassis point, ground bar orterminal is highly recommended. An even greater degree of shield performance can beachieved by using metallic glands for shielded cable entry into metal enclosures. Exposeenough of the braid/foil/drain where it passes through the gland so that the shield materialscan be wrapped backwards onto the cable jacket and captured inside the gland, and tight-ened up against the metal interior.

Inductive loads connected to the low voltage Alarm Contacts are not recommended.However, if this becomes a necessity, adhere to proper techniques and wiring practices.Install an appropriate transient voltage suppression device (low voltage MOV, Transzorb,or R/C) as close as possible to the inductive device to reduce the generation of transients.Do not run this type of signal wiring along with other I/O or DC in the same shieldedcable. Inductive load wiring must be separated from other circuits in conduit by using anadditional cable shield on the offending cable.

In general, for optimum protection against high frequency transients and other distur-bances, do not allow installation of this Analyzer where its unshieled I/O and DC circuitsare physically mixed with AC mains or any other circuit that could induce transients intothe Analyzer or the overall system. Examples of electrical events and devices known for thegeneration of harmful electromagnetic disturbances include motors, capacitor bank switch-

!CAUTION

| ix

WARRANTY AND CLAIMS

We warrant that any equipment of our own manufacture or manufactured for us pursuant to our specifi-cations which shall not be, at the time of shipment thereof by or for us, free from defects in material orworkmanship under normal use and service will be repaired or replaced (at our option) by us free ofcharge, provided that written notice of such defect is received by us within twelve (12) months from dateof shipment of portable analyzers or within eighteen (18) months from date of shipment or twelve (12)months from date of installation of permanent equipment, whichever period is shorter. All equipmentrequiring repair or replacement under the warranty shall be returned to us at our factory, or at such otherlocation as we may designate, transportation prepaid. Such returned equipment shall be examined by usand if it is found to be defective as a result of defective materials or workmanship, it shall be repaired orreplaced as aforesaid. Our obligation does not include the cost of furnishing any labor in connection withthe installation of such repaired or replaced equipment or parts thereof, nor does it include the responsi-bility or cost of transportation. In addition, instead of repairing or replacing the equipment returned to usas aforesaid, we may, at our option, take back the defective equipment, and refund in full settlement thepurchase price thereof paid by Buyer.

Process photometric analyzers, process moisture analyzers, and sampling systems are warranted toperform the intended measurement, only in the event that the customer has supplied, and AMETEK hasaccepted, valid sample stream composition data, process conditions, and electrical area classification priorto order acknowledgment. The photometric light sources are warranted for ninety (90) days from date ofshipment. Resale items warranty is limited to the transferable portion of the original equipmentmanufacturers warranty to AMETEK. If you are returning equipment from outside the United States, astatement should appear on the documentation accompanying the equipment being returned declaringthat the goods being returned for repair are American goods, the name of the firm who purchased thegoods, and the shipment date.

The warranty shall not apply to any equipment (or part thereof) which has been tampered with or alteredafter leaving our control or which has been replaced by anyone except us, or which has been subject tomisuse, neglect, abuse or improper use. Misuse or abuse of the equipment, or any part thereof, shall beconstrued to include, but shall not be limited to, damage by negligence, accident, fire or force of theelements. Improper use or misapplications shall be construed to include improper or inadequate protec-tion against shock, vibration, high or low temperature, overpressure, excess voltage and the like, oroperating the equipment with or in a corrosive, explosive or combustible medium, unless the equipmentis specifically designed for such service, or exposure to any other service or environment of greaterseverity than that for which the equipment was designed.

The warranty does not apply to used or secondhand equipment nor extend to anyone other than theoriginal purchaser from us.

THIS WARRANTY IS GIVEN AND ACCEPTED IN LIEU OF ALL OTHER WARRANTIES, WHETHEREXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION AND WARRANTIES OF FITNESS OROF MERCHANTABILITY OTHER THAN AS EXPRESSLY SET FORTH HEREIN, AND OF ALL OTHEROBLIGATIONS OR LIABILITIES ON OUR PART. IN NO EVENT SHALL WE BE LIABLE UNDER THISWARRANTY OR ANY OTHER PROVISION OF THIS AGREEMENT FOR ANY ANTICIPATED ORLOST PROFITS, INCIDENTAL DAMAGES, CONSEQUENTIAL DAMAGES, TIME CHANGES OR ANYOTHER LOSSES INCURRED BY THE ORIGINAL PURCHASER OR ANY THIRD PARTY IN CON-NECTION WITH THE PURCHASE, INSTALLATION, REPAIR OR OPERATION OF EQUIPMENT, ORANY PART THEREOF COVERED BY THIS WARRANTY OR OTHERWISE. WE MAKE NO WAR-RANTY, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OFFITNESS OR OF MERCHANTABILITY, AS TO ANY OTHER MANUFACTURERS EQUIPMENT,WHETHER SOLD SEPARATELY OR IN CONJUNCTION WITH EQUIPMENT OF OUR MANUFAC-TURE. WE DO NOT AUTHORIZE ANY REPRESENTATIVE OR OTHER PERSON TO ASSUME FOR

x | Dycor QuadLink Residual Gas Analyzer

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Overview | 1-1

OVERVIEW

Dycor QuadLink Residual Gas Analyzer

The Dycor QuadLink is a residual gas analyzer that provides simultaneousdata acquisition over an RS-485 network. It is a quadrupole-based intelli-gent mass spectrometer that has all the sensor electronics plus an inte-grated microprocessor built in.

QuadLink System

The standard configuration for the QuadLink residual gas analyzer con-sists of the following components:

• Open source quadrupole mass spectrometer in 100 or 200 AMU range;electronics, preamplifier and RF power supply.

• Faraday cup detector or microchannel plate electron multiplier detec-tor.

Backlit LCD display for instant updates of system status and diagnos-tics.

Battery-backed-up RAM,

RS-232 port for local control of a single sensor, and

RS-485 port for networking multiple sensors.

1-2 | Dycor QuadLink Residual Gas Analyzer

Options for QuadLink System

• Optional integrated Dycor System 2000 Software that provides theability to integrate other readings such as pressure, temperatureand valve control.

If you are using the QuadLink without System 2000 software, refer tothe section on QuadLink serial communications. This section describesthe serial communications protocol used by the QuadLink power sup-ply.

If you are using Dycor System 2000 software, you will need an RS-485converter to operate the software.

Overview | 1-3

Upgrading from Another Dycor Analyzer

Upgrading from an MA-Series Analyzer

If upgrading from an MA analyzer, you will need the MA Harness kit.Contact the factory for help on how to perform this upgrade.

Upgrading from an M-Series Analyzer

If you purchased a QuadLink upgrade box to upgrade your M-Series powersupply to a QuadLink power supply follow the instructions below for in-stallation.

• Attach one end of the cable supplied with the upgrade to the connec-tion labeled To Control on the M Series power supply.

• Attach the other end to the QuadLink upgrade box connection labeledPower Supply.

• Connect to the QuadLink upgrade box using the power cable suppliedwith the upgrade.

After completing these steps, your M- or MA-Series power supply acts as aQuadLink power supply. All other installation instructions are the same asif you purchased a QuadLink power supply.


Mass Spectrometer Theory

The mass spectrometer allows you to identify the masses of individualmolecules that have been converted to ions from a given sample. This tech-nique is unique in that it provides a fingerprint identification for the struc-tural and chemical properties of these molecules. The quadrupole massspectrometer is one of a specialized subset of mass spectrometers that mea-sure background gases in an existing vacuum chamber.

Mass Spectrometer Hardware

Once the sample reaches the mass spectrometer hardware, three processestake place:

• Ionization• Separation• Detection

Repeller Filament Source Grid Focus Plate

. .

. .. .

. .

. .

Filament

RepellerSource Grid

Focus Plate

Top AluminaCollar

Mass Filter

Figure 1-1.Mass spectrometerhardware.

Overview | 1-5

Ionization

During ionization, sample molecules are turned into ions that are thenfocused towards the quadrupole mass filter to be detected. The processoccurs in the source which consists of a filament, filament electron repel-ler, ionizer body, and focusing plate. See Figure 1-1.

The filament produces electrons. As current flows through the filament, itis electrically heated to incandescence and emits free electrons. Once theelectrons are free, they are accelerated towards the ionizer body by thepotential difference between the filament and the ionizer body. As a beamof electrons accelerates towards the ionizer body, the electrons collide withthe vaporized sample in the center of the ion volume and create ions.

Once the positive ions are formed, they are extracted from the ion regionand focused towards the quadrupole mass filter by a difference in poten-tial energy.

EI ionization

The energy of the bombarding electrons is much greater than the bondsthat hold the molecule together. When a single electron is removed, a posi-tive ion is created; this is referred to as a molecular ion. When the bom-barding electrons cause the molecular bonds to break, fragment ions form.This fragmentation process is known as electron impact ionization (EI).

Operation of the mass spectrometer depends on maintaining low vacuumpressures. These pressures take into account not only the operational pres-sures of the mass spectrometer, but also the pressures of the samplingsystem environments.

Separation

Once the ions reach the quadrupole mass filter, they are filtered accordingto their mass-to-charge (m/z) ratio. Each ion has an identifiable mass. Thequadrupole mass filter is constructed of four electrically-conducting, par-allel cylindrical rods. A constant direct current (DC) voltage and an alter-nating radio-frequency (RF) voltage is applied along the length of the rods.Through proper electronic tuning, these voltages set the criteria for theions that pass through the quadrupole.

As an ion enters the quadrupole mass filter, the RF and DC fields cause itto undergo oscillations. Depending upon the criteria set for motionthrough the quadrupole, an ion either strikes a rod or passes through thequadrupole. Ions meeting the m/z criteria have stable trajectories andemerge from the mass filter assembly (Figure 1-2). Ions with other m/z


values have unstable trajectories and are neutralized as they strike one ofthe rods.

Ions that successfully pass through the quadrupole are again focused to-wards the detector using an exit aperture which has an applied negativevoltage that attracts the positively charged ions.

Detection

The simplest detection setup consists of a Faraday cup detector. An elec-tron multiplier is used for amplified sensitivity.

A Faraday cup detector is a closed structure except for an opening thatallows the ions to enter. As the positive ions exit the quadrupole mass filter,they strike the detector, creating a current. This current is then sent to thepreamplifier for amplification and then to the data system for display.

When an electron multiplier is used, the ions are attracted to the multiplierbecause of its negative charge. As the ions strike the multiplier, secondaryelectrons are emitted. This creates a cascading effect as each secondaryelectron generates more secondary electrons as they move down the mul-tiplier wall, amplifying the signal by approximately one thousand.

The Dycor system uses a microchannel plate (MCP) electron multiplier. Itconsists of an array of millions of small glass capillaries fused together in

-

+-

+

+

+

+ ++ +

++

+ DC - DC

IonizationChamber

FocusLens

Quadrupole

ExitLens

Detector

Figure 1-2.Quadrupole massfilter.

Overview | 1-7

the shape of a disk. The inside wall of each channel has a resistive, electri-cally semiconductive layer, forming independent electron multipliers. Asthe ions are approaching the MCP, a positive electrical gradient pulls theelectrons into the MCP. As they cascade down and strike the channel walls,they generate secondary electrons. The Dycor MCP has the advantage inthat it is air stable and is especially beneficial for detection of low-levelspecies.

Data System

Overall control of the system, acquisition of data, and access to collecteddata is accomplished through the Dycor System 2000 software. Adjust-ment of all instrument parameters that affect sampling, ionization, separa-tion and detection are software controlled. All data acquisition parametersare also set using the software.


Technical Support

AMETEK/Dycor is committed to providing you with the best technicalsupport in the industry. If you need service or application assistance, pleasecall AMETEK at (412) 828-9040, or call your local AMETEK/Dycor represen-tative.

If you need to return equipment, you will be asked to provide the follow-ing information before obtaining a Return Material Authorization (RMA)number.

Billing and shipping address

Model number

Serial number

Purchase order number

Telephone number

Before returning material, you must get an RMA number from thefactory.

!NOTE

Specifications | 2-1

QUADLINK SPECIFICATIONS

Mass Range:

1 - 100 AMU standard; 1-200 AMU optional

Operating Pressure Range:

10 -4 Torr to ultrahigh vacuum

Minimum Detectable Partial Pressure:

5 x 10 -12 Torr (5 x 10 -14 Torr for electron multiplier units)

Resolution:

Adjustable to constant peak width (0.5 AMU at 10% height)

Emission Current:

0.1 to 10 mA; 50 mA to degas

Electron Energy:

30 to 150 volts to operate; 200 volts to degas

Ion Energy:

1 to 10 volts


Source Sensitivity (Faraday Cup):

2 x 10 -4 amps per Torr at detector (measured with nitrogen at mass 28with peak width = 0.5 at 10% height and 1 x 10 -3 amps emission current)

Power Requirements:

110 VAC 1 amp or 220 VAC 0.5 amp

Stability:

Mass stability: ± 0.1 AMU after 30-minute warm-up;

Peak Height: ± 2% after 30-minute warm-up.

RS-232 Serial Communications Interface:

Isolated; baud rate 38,4009-pin, female D-connector

Accessory Output

2 Digital TTL1 Analog 0-10 volts15-pin, female D-connector

RS-485 Addressable COmmunications Interface:

Isolated, baud rate selection of 1200 to 38400 programmable address; two9-pin, female D-connectors

Physical Dimensions:

Weight 14 lb. (6.3 kg)Width 16 (40.6 cm)Length15 (38.1 cm)Height 3.5 (8.9 cm)

Installation | 3-1

INSTALLATION

This chapter contains information on the installation of the QuadLink sys-tem including the following:

• Mechanical installation

• Communication setup

• Accessory Outputs


QuadLink System Mechanical Installation

Make sure that all power switches are turned off before installingDycor QuadLink components. Also make sure that power has beenremoved from the system.

This user manual assumes you are familiar with high vacuum systems andwill handle the quadrupole head accordingly to avoid contamination ofthe internal surfaces. Please refer to Chapter 6 of this manual for properhandling procedures before continuing.

The QuadLink source is shipped wrapped in a protective covering. Checkall parts to ensure that nothing has been damaged. If you discover dam-age, report it to the factory immediately. The following is an overview ofthe steps required to install a QuadLink system.

1. Visually check the filament for integrity

2. Install the source assembly into the vacuum system.

2. Connect the electrometer to the source.

3. Connect the electrometer to the 24 VDC power supply.

4. Connect the power supply to AC line power.

5. Connect the QuadLink(s) to the PC.

Check Sensor Filament.

1. Before installing the sensor, check the filament to ensure that it has notbeen damaged during shipment. Visually inspect the filament to makesure that it is not broken.

2. Using a standard ohm meter, check the continuity of the filament tomake sure that an open circuit does not exist between Pins 3 and 8 ofthe vacuum feedthrough pins (see Figure 3-1). A resistance of less than1 ohm is required.

3. Check the resistance between Pins 3 or 8 to all other pins. They shouldall show an open resistance to operate properly.

!CAUTION

Installation | 3-3

Connect the Sensor to the Vacuum System

The sensor is contained within a stainless steel nipple (see Figure 3-2). Thenipple ends with a 2 3/4” Conflat flange that will mate to your vacuumchamber. A copper gasket is included to provide a high integrity metal-to-metal seal between the source and your chamber. When inserting the sourceinto your vacuum chamber, make sure that the repeller grid does not shortagainst the inside of the chamber walls.

1. Using a new copper gasket between the flange and the source, installthe source into the nipple so that the repeller clears the chamber walls(Figure 3-2). A new copper gasket must be used each time the sourceis removed and reinstalled.

Figure 3-1.Keyway from outsidethe sensor flange.

1

2

8

9

7

6

54

3

Keyway

Filament

Repeller Grid

Focus Plate

Filament

Source Plate

Electrometer

Source

FeedthroughPins

Nipple

StainlessSteel Bolts

2 3/4”

Conflat Flange

Copper Gasket

Repeller Grid

Vacuum

Figure 3-2.Sensor assembly.


2. Align the source at the 7 o’clock position on the keyway.There is a keyway on the feedthrough side of the source (Figure 3-1).This keyway ensures proper pin orientation when the electrometer isinstalled. When mounting the source, we recommend that the keywaybe in the 7 o’clock position. This position will allow the electrometercable to hang straight down once it is installed, minimizing strain onthe cable.

3. Bolt the source flange in place using the screws and washer provided.Tighten in a star pattern to ensure a good seal.

Connecting the Source to the Electronics

Power to the QuadLink must be off.

The source was already checked at the factory where the filament integritywas validated.

• Visually align the slot on the electrometer to the keyway on the middlefeedthrough of the source assembly (Figure 3-3). This ensures that theelectrometer is properly connected to the source. A loose connectioncan cause a filament trip message to appear on the display screen.

The electrometer can be disconnected and then reconnected to the sourcesimply by pulling it from the source and pushing it back on. Do not twistthe electrometer on the analyzer, this will damage the vacuum feedthroughs.

The electrometer must be disconnected from the source during bake-out so as not to damage the electronics.

Bake-out of the source

Bake-out of the source must be conducted under a vacuum to minimizeoxidation of the analyzer head components. This is normally done only forlow pressure work. When baking near the maximum temperature (350° C),limit the rate of change to 5 °C per minute. This protects the analyzerduring repeated bakes.

!CAUTION

!WARNING

Installation | 3-5

Connecting the Electrometer to the Power Supply

There will be two or three cables attached to the electrometer:

• a coaxial cable to supply the RF power to the mass filter (labeled RF onthe cable),

• a flat ribbon cable to supply and monitor numerous other voltages andsignals to and from the source, and

• if you have the multiplier version of the electrometer, there will be acoaxial cable labeled HV that is provided to supply the High Voltage tothe electron multiplier.

Follow these steps to connect the electrometer to the power supply (Figure3-3):

1. Connect the cable marked RF to the connector labeled RF on the rearof the power supply. Line up the slot on the RF cable with the key onthe top of the RF connection on the power supply and press the cablein. Turn it until it locks.

2. Connect the flat ribbon cable to the 37-pin female connector on thepower supply (marked “analyzer”). This connector is keyed to preventan incorrect cable connection.

3. If you have the electron multiplier electrometer, connect the cable la-beled HV (high voltage) to the connector labeled HV on the powersupply.

FRONT VIEWElectrometer

HV Coaxial Cable

used only with

multiplier option

H.V. RS-485

RS-485

POWER

ACCESSORY ANALYZER

R.F.

Flat

Rib

bon

Cabl

e

RF Coaxial Cable

POWER SUPPLY(Rear View)

Figure 3-3.QuadLink connectionsfrom rear of powersupply toelectrometer.


Switching Between 110 and 220 Volts AC Line

The power requirements for the QuadLink power supply are 110 or 220VAC at 200 watts 50/60 Hz. To switch from 110 to 220 volts, it will be neces-sary to do the following:

1. Turn off the power switch to the QuadLink power supply.

2. Remove the power cord from the QuadLink power supply.

3. Slide the plastic door on the power connector to the left to expose thefuse.

4. Using a pair of pliers, remove the small circuit board directly below thefuse.

5. Turn the card 180° and install it with the side labeled “240” visible. The240 should appear legible to you as you are pushing it into place andshould NOT appear upside down.

6. Slide the door to the left and install a 220-volt power cord.

Connect the Power Supply to the AC Line Power

Be sure that the power switch on the power supply is turned off.

1. Plug the power cord that is provided with the power supply into thepower outlet located on the rear of the power supply.

2. Plug the opposite end of this power cord into the appropriate AC poweroutlet.

Since heat is given off during normal operation, you must take care not toobstruct the airflow through the heat sink on the rear panel of the powersupply. If the power supply is to be rack-mounted, it should not be placedin a closed rack without air circulation.

!CAUTION

Installation | 3-7

Communications Setup

Connect QuadLink(s) to PC

This section describes how to connect QuadLink analyzers to the PC run-ning the software that will analyze the incoming data. Usually this is theDycor System 2000 software although it can also be your own software.

Single quadLink connection (RS-232)

If connecting only a single QuadLink to the PC, you will need:

• Serial cable with a 9-pin DB-9 male connector on one end of the cableand a DB-9 female connector on the other end.

• Connect the male connector end of the cable into the front RS-232 porton the QuadLink

• Connect the female connector end into the RS-232 port on your PC.

With an RS-232 connection, the distance limit between the PC and theQuadLink power supply is 50 feet. If you need a longer distance, pleaseconsult the factory (RS-485 communications must be used if distance isover 50 feet).

If using your QuadLink with System 2000 software, you will also need toopen the System 2000 Setup program and set the QuadLink port to theaddress corresponding to the serial port (usually COM1 or COM2) wherethis serial cable has been connected on the System 2000 PC.

Figure 3-4.RS-232 communicationcables.

QuadLink DB-9M

Pin 2 Transmit

Pin 3 Receive

Pin 5 Ground

QuadLink DB-9M

Pin 2 Transmit

Pin 3 Receive

Pin 5 Ground

Computer DB-9F

Pin 2 Receive

Pin 3 Transmit

Pin 5 Ground (required)

Computer DB-25F

Pin 3 Receive

Pin 2 Transmit

Pin 7 Ground (required)


Networking multiple QuadLinks (RS-485)

If you intend to use multiple QuadLinks with System 2000 software,you will need to have an RS-485 converter to communicate with yourPC.

!NOTE

!NOTE

You will need an RS-485 converter to network multiple QuadLinks andcommunicate with the Dycor System 2000 software on your PC.

Each QuadLink power supply includes an RS-485 cable. Connect the firstRS-485 cable between the PC and the first QuadLink in the network (seeFigure 3-5). On the QuadLinks, the RS-485 connection is labeled RS-485.Then, daisy chain the remainder of the QuadLink power supplies.

For the last power supply in the network, insert the termination plug (PN72819SE) into the unconnected RS-485 connection (termination plug lookslike an RS-485 connector without the cable).

If two QuadLink power supplies have the same address, turn one ofthem off, then renumber the other QuadLink’s power supply address.

Rear of PC

RS-485Converter

9-Pin, D-TypeCommunication Cable

Rear ofQuadLink PowerSupply



Power Cord

Power Cord

Power Cord

AC Power Line

AC Power Line

AC Power Line

RS-485Cable

RS-485Cable

Termination Plug

Figure 3-5.RS-485 QuadLinknetwork

Installation | 3-9

QuadLink LCD Display

The LCD display on the front of a QuadLink power supply shows whethera QuadLink is actively scanning, provides its network address, and dis-plays system messages.

This section describes how to interpret the text you see on the LCD displayon the front of the QuadLink power supply.

Status

01N Idle QC MUL FIL

Network Address - 01 to 31

Port in Use - N for RS-485 network; L for RS-232 port.

QC - Quad Check on

MUL - Multiplier on

FIL - Filament on

Idle QuadLink is ready to scan.Scan Scan is on.Degas Ionizer degas is enabled.Rftun Automatic RF tune is in progress.Wait Scan delayed by the Scan Interval command.Bfull Scan data buffers are full.

01N Idle QC MUL FIL

Total Pres: 3.4E-09

Messages

Messages are displayed on the second line of the LCD display.

Total Pres: 2.5E-09 Total Pressure - Displayed whenever the fila-ment is on and the QuadLink is idle or QC isenabled.

F = 2.80 RF = 6.56 Auto RF tune - F is the frequency; RF is theRF tune value.


F = 2.86 DONE! DONE! is displayed when the tune is success-ful.

Protect exceeded Filament tripped The total pressure ex-ceeded about 1.0E-03 Torr. The QuadLink au-tomatically turned off the filament.

RF tune failure The total pressure exceeded the user-definedprotect pressure. The QuadLink automati-cally turned off the filament.

Filament open The RF frequency is wrong. This could alsomean that the electrometer cable is discon-nected.

Power Supply Failure The QuadLink has detected a filament fail-ure.

PS Port Error: 1 The QuadLink CPU is unable to communi-cate with he quadrupole power supply CPU.

RS-232 Error: 1 Communications error - The PS port is aninternal port used for communications be-tween the QuadLink CPU and the quadru-pole power supply CPU.

RS-485 Error: 1 Communications error codes:

1. Port hardware failure.

2. More than two seconds elapsed betweencommand characters.

3. Characters arriving too fast. Should neveroccur.

4. Bad characters received. Could be due towrong baud rate or noisy communicationsline.

Installation | 3-11

Accessory Output

The QuadLink has two digital outputs and one analog output availablethrough a DB-15F connector located on the back panel of the QuadLink.

The ditigal outputs are TTL signals (0V or 5V)

Pin 5 Digital Output 0 “Dig Out 0” in the System 2000

Pin 6 Digital Output 1 “Dig Out 1” in the System 2000

Pin 13 Digital Common

The analog output has a 12-bit resolution with a range of 0 to 10V.

Pin 4 Analog Output “Ana Out 0” in the System 2000

Pin 14 Analog Common

All other pins must be left unconnected.

Accessory Port Pinout

Pin 1 Unused

Pin 2 Unused

Pin 3 Unused

Pin 4 Analog output voltage: 0 to 10 VDC

Pin 5 Digital Output 1: TTL (+5 VDC) level outputMaximum load on Pin 5: 1 TTL Load(Sink: 2mA, Source: 250 uA)


Pin 7 +5 VDC supply

Pin 8 -15 VDC supply

!NOTE


Pin 9 Circuit Ground






Pin 15 +15 VDC supply

Installation | 3-13

Accessory Port Pinout

Pin 1 Unused

Pin 2 Unused

Pin 3 Unused

Pin 4 Analog output voltage: 0 to 10 VDC



Pin 7 +5 VDC supply

Pin 8 -15 VDC supply







Pin 15 +15 VDC supply

User Interface Setup and Serial Communications| 4-1

SERIAL COMMUNICATIONS

Communications Protocol

Host Communications

The QuadLink has two serial ports, an RS-232 and an RS-485. TheQuadLink will respond to a command from either port at any time. TheRS-485 port allows up to 31 power supplies to be connected in amultidrop network configuration to one host. The RS-485 port can beoperated in either two- or four-wire mode.

Protocol

>AAFFddddCC[CR] CommandA[CR] AcknowledgeAddddCC[CR] Acknowledge with dataNEE[CR] Error with code

Char Function> Command startAA Two character ASCII decimal node address (Ignored)FF Two character ASCII hex function codedddd Up to 240 characters of ASCII dataCC Two character ASCII hex checksum; ignored if set to ??A AcknowledgeN ErrorEE Error code[CR] End of message, hex 0D

If communicating through the RS-485 port, the QuadLink will onlyrespond if a command node address matches its own. If communicatingthrough the RS-232 port, the node address is ignored. The QuadLink willrespond to any address.

The checksum is a modulo 256 summation of the characters making upthe function code and data.


Function: 00 Status

This is the only command that will work before you log in.

If no parameter supplied, returns the current QuadLink status as a two-digit hex value.

Bit 0: 0x01 Protect pressure exceeded

Bit 1: 0x02 Filament open

Bit 2: 0x04 Filament half open

Bit 3: 0x08 Filament trip

Bit 4: 0x10 RF failure

Bit 5: 0x20 Power supply communications error

Bit 6: 0x40 Communicating through the RS-232 port

Bit 7: 0x80 Multiplier option present

If sending a subfunction code in the first byte of the data block:

Subfunction: R Reset

Logs in this port, stops scanning, resets system, clears error anddisplay.

Subfunction: L Log In

Requests log-in to the QuadLink. Stops scanning, resets system, clearserrors and display.

Subfunction: O Log Out

Log-out from the QuadLink. Stops scanning, turns off filament,multiplier, and degas mode.

If the other port is in use, the request is processed the next time theother port logs out. This prevents the other port from logging out andthen back in before you try again.

ReturnsA if successful.N09 if the other port is in use.


Subfunction: C Cancel Log In

Cancel a pending log-in. Call this if you tried a log-in and the otherport was in use and you want to quit waiting.

Subfunction: O Log Out

Log-out from the QuadLink. If this port was logged-in, then stopscanning, turn off the filament, multiplier and degas mode. Log-in theother port itf it is waiting.

Subfunction: X Log Out if waiting

Log-out from the QuadLink if, and only if, the other port is waiting.Log-In the other port if it was waiting.

Subfunction: I Information

Get information string.

ReturnsDycor QuadLink N.n Where N.n is the firmware version, e.g. 1.0.

Subfunction: A Repeat Last ACK

Repeat the last acknowledge message sent. if an ACK message isreceived with errors, use this to retransmit it.

ReturnsA copy of the last ACK message sent.


Function: 01 Auto RF Tune

Starts the automatic RF tune procedure. Not allowed when scanning.

Parameters

1 (Starts the auto tune RF)

ReturnsIf no parameter supplied, returns 1 if auto RF tune is still in progress. 0if done.

Function: 02 Tune Data Read-only

Get the latest tune data.

ReturnsA string in the format 3.52E-08 1.0E-03 7.216 2.1 3.0 The values are totalpressure, emission current, RF tune, filament voltage, and filament cur-rent.

Function: 03 Scan

Start or stop scanning. Clears the data buffer when started. Sets thenumber of scans.

Parameters

scans Zero stops scanning. A-1 scans forever. Range is -1, or 0 to 32767.

ReturnsIf no parameter supplied, returns the number of scans remaining.


Function: 04 Filament

Turn the filament on or off. If scanning, does not take effect until the nextscan.

Parameters

1 (Turn on)2 (Turn off)

ReturnsIf no parameter supplied, returns the current value.

Function: 05 Multiplier

Turns the multiplier on or off. If scanning, does not take effect until thenext scan.

Parameters


ReturnsIf no parameter supplied, returns current value. If this is not a multiplierpower supply, then always return -1.


Function: 06 Channel Parameters

Sets the channel type and parameters. No changes are allowed if scan-ning.

Parameters

chan A low high dwell samples [gain] [offset] [offset2] (Analog mode)chan B low high dwell [gain] [offset] [offset2] (Bar mode)chan T mass dwell [gain] [offset] [offset2] (Tabular mode)chan P [gain] [offset] [offset2] (Pressure-total pres-

sure)chan N (Tune mode)chan D (Disable)C (Disables all channels)chan (Return current chan-

nel parameters)

chan is the channel number. Range: 0 to 31.low is the low mass. Range: 1 to 219.high is the high mass. Range: 2 to 220.

dwell is the sample dwell time. Range: 3, 4, 5, 10, 15, 30,60, 120, 250, 500, 1000,2000, 4000, 8000, 16000

samples is the samples per AMU. Range: 4 to 15.gain is an optional parameter for sample gain. Defaults to 1.0 if not set.offset is an optional parameter for sample offset. Defaults to 0 if not set.offset2 is an optional parameter for sample offset. Defaults to 0 if not set.

The data values are modified by the following formula:

NEW_VALUE = ((VALUE + offset) x gain) + offset2

ReturnsIf just chan is supplied, then one of the above strings is returned (includ-ing gain, offset, offset2).


Function: 07 Scan Interval

Sets the number of seconds between scans.

Parameters

interval - Range: 0 to 32767.

ReturnsIf no parameter supplied, returns current value.

Function: 08 Analog Output

Sets the Power Supply analog output voltage. If scanning, does not takeeffect until the next scan.

Parameters

value Range: 0 to 4095.



Function: 09 Digital Output

Sets one or both of the Power Supply the digital outputs. If scanning, doesnot take effect until the next scan.

Parameters

0 (All off)1 (#1 on, #2 off)2 (#1 off, #2 on)3 (all on)10 (#1 off, #2 dont change)11 (#1 on, #2 dont change)20 (#1 dont change, #2 off)22 (#1 dont change, #2 on)

ReturnsIf no parameter supplied, returns current value: 0, 1, 2, or 3.

Function: 0B Display Message Write-Only

Display a message on the LCD panel. If the message is more than 20characters, then it will scroll. To erase the message, send a Display Mes-sage command with one blank (ASCII 32).

Parameters

messageUp to 79 characters


Function: 0C Calibration Parameters

Sets the calibration parameters for the head.

Parameters

Freq LoMass HiMass LoPos HiPos LoRes HiRes LoSen HiSen Cal Tsens Mult

Freq PLL frequency in MHz. Range: 2.000E+06 to 3.000E+06.LoMass Low calibration mass. Range: 1 to 100HiMass High calibration mass. Range: 1 to 200LoPos Low position. Range: -10.00 to 10.00.HiPos Low position. Range: -10.00 to 10.00.LoRes Low resolution. Range: 50 to 4100.HiRes High resolution. Range: 50 to 4100.LoSen Low sensitivity. Range: 3.00 to 10.00.HiSen Low sensitivity. Range: 3.00 to 10.00.Cal Amplifier calibration. Range: 1.0E-10 to 1.0E10.TSens Total sensitivity. Range: 0.1 to 999.9.Mult Multiplier voltage. Range: 0 to -1300.

ReturnsIf no parameter supplied, then the calibration parameter string is re-turned. If not a multiplier power supply, Mult always returns zero.


Function: 0D Ionizer Parameters

Sets the ionizer parameters for the head.

Parameters

Emis ElEnergy Focus Repeller

Emis Emission current. Range: 1.0E-04 to 1.0E-02.

ElEnergy Electron energy. Range: -150.0 to -30.0

Focus Focus voltage. Range: -200.0 to +10.0.

Repeller Repeller voltage. Range: -170.0 to -30.0.

ReturnsIf no parameter supplied, then the ionizer parameter string is returned. Ifmultiplier power supply, Repeller always returns zero.

Function: 0E Autozero

Turn the autozero option on or off. When turned on, the scanning timewill double. For each data point, two readings are taken. One normal, andone with the mass filter blocking all ions.

Parameters




Function: 0F Set Time

Set the real time clock. Note that the time and date are not maintainedwhen powered off.

Parameters

month/day/year hour:minute:second

month 1 to 12.day 1 to 31.year four digit year, e.g. 1998hour 00 to 23. This must be in 24-hour format.minute 00 to 59.second 00 to 59.

ReturnsIf no parameter supplied, returns current date and time in the format:

month/day/year hour:minute:second.hundredths


Function: 10 Get Data

Get scan data for one channel for each call.

ParametersC Clear scan data.T Return time of scan before each scan.P Return total pressure, if available, before each scan.N Set maximum number of data points to return 1 to 16.

ReturnsEcode (Error status)Tpressure (Optional total pressure)

S[date time] channel count data1 data2 data3 data4 ... dataN (Start of scandata)

Cchannel count data1 data2 data3 data4 ... dataN (Continued scan data)on same channel)

channel count data1 data2 data3 data4 ... dataN (Scan data)

O (Scan is off - no data)No data returned indicates that scanning is on, but no data is ready.

If S is the first returned character, it indicates the start of a set of scan data. IfS is returned, it is optionally followed by the date and time of the start of thescan. If C is the first returned character, it means that additional scan datafor the channel is being returned.

code Two digit hex error code - see STATUS command.

date Format: 06/10/94.

time Format: 15:42:23.44.

channel Channel number from 0 to 31.

count Number of data values returned from 1 to 16. Tabular and TotalPressure mode channels always return one data value. Tune mode chan-nels return five values.

data Scan data in the format: 1.23E-08 except for tune mode. If tunemode, the values are total pressure, emission current, RF tune, filamentvoltage, and filament current.


EXAMPLE:

S06/10/94 09:42:39.12 0 5 3.54E-08 1.0E-03 7.216 2.1 3.0 1 3.51E-051 1 3.51E-052 16 5.42E-08 5.43E-08 [data not shown] 5.43E-08 5.44E-08 5.45E-08 5.46E-08C2 16 5.41E-08 5.42E-08 [data not shown] 5.43E-08 5.44E-08 5.45E-08 5.46E-08C2 4 5.44E-08 5.43E-08 5.41E-08 5.41E-08S06/10/94 09:42:39.12 0 5 3.54E-08 1.0E-03 7.216 2.1 3.0 1 3.51E-051 1 1.52E-072 16 5.43E-08 5.40E-08 [data not shown] 5.04E-08 5.04E-08 5.34E-08 5.44E-08C2 16 5.34E-08 5.34E-08 [data not shown] 5.43E-08 5.34E-08 5.34E-08 5.34E-08C2 4 5.44E-08 5.45E-08 5.46E-08 5.47E-08

The previous shows the returned strings from calls to function 10. Chan-nel 0 is set to Tune Mode. Channel 1 is a Tabular mass. Channel 2 is in Barmode with 36 data points.


Function: 11 RS-232

Sets the RS-232 baud rate.

ParametersBaud Port baud rate. Range: 1200, 2400, 4800, 9600, 19200, 38400, 57600

ReturnsIf no parameter supplied, then the current state is returned.

Function: 12 RS-485

Sets the RS-485 baud rate.

ParametersBaud Address

Baud Port baud rate. Range: 1200, 2400, 4800, 9600, 19200, 38400, 57600

Address Two digit decimal node address Range: 01 to 31


Function: 13 Degas

Enable degas mode. Not allowed while scan is on.

Parameters1 (Turn on)0 (Turn off)



Function: 15 Quad Check

Sets the filament protect pressure and enables quad check.

Parameters

Filprot QChk

FilProt Filament protect limit. Range: 1.0E-16 to 1.0E-03.QChk Quad check on/off. Range: 0 or 1.

ReturnsIf no parameters supplied, then the Quad Check parameter string isreturned.


Error Codes

N01 Bad Command

The command sent is not recognized.

N02 Checksum

The calculated checksum didnt match the checksum sent.

N05 Write-Only

The command is write-only. Cant return a query.

N06 Out of Range

The parameter sent is out of range.

N07 Memory

The command tried to allocate memory and failed.

N08 Reset

The QuadLink has been reset. You must send a 00R or 00L command.

N10 Scan

The command sent is not allowed while scanning.


Operation

In order to send commands to the QuadLink, the host must log in bysending the 00L function. If the other port is in use, keep trying until youget in.

The QuadLink is organized into 32 data channels. Each of the channelscan be set to either tabular (a single mass) or to analog, bar, total pressure,tune data, or disabled. A scan consists of acquiring data for all activechannels. The date and time is stored with each scan.

All parameters are retained when the QuadLink is turned off.


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Sampling Systems | 5-1

VACUUM AND PRESSURE REDUCTION SYSTEMS

This chapter describes the pumping and pressure reduction systemsavailable as options on the Dycor analyzers. They include the following:

• Pumping Station - See Figure 5-1.

• Pressure Reduction System (M240) - See Figure 5-2.

• Atmospheric Pressure Sampling System (M250) - See Figure 5-4.


Pumping System

Installation

1. Use a 7/16" wrench to loosen the four nuts that secure the roughingpump during shipment. The springs that the roughing pump rests onshould not be compressed but rather fully decompressed (withinlimits) to allow them to act as vibration dampers.

2. The rotary vane roughing pump is shipped with oil. The oil levelshould be about half-way up the oil sight glass when the pump issitting on a level surface. The exhaust port is plugged during ship-ment to reduce the possibility of oil spilling. Remove this plug.

3. Make sure that all valves are closed on the pressure reduction system.You can now turn on the pumping system by pressing the pumppower button on the pumping station controller.

4. If the system is sealed, the rotational speed indicator will indicate fullspeed by moving fully to the right within a few minutes. If the systemis not sealed, the turbomolecular pump will never reach full speedand may turn itself off due to thermal overload. If this happens, letthe system cool and then try to locate the coarse leak. Since the sys-tems are tested extensively at the factory, double check any systemconnections made by the user. When the system is restarted after athermal shutdown, the STANDBY button must be pressed at the sametime as the START button. Press the STANDBY button to allow thepump to achieve full speed.

5. When the turn gets to full rotational speed, the analyzer is ready to beused. The analyzer can now be used for further leak checking in thehigh vacuum realm.

6. When you want to vent your system, turn off the source electronicsand push the pump power button again. The system will automati-cally vent.

Allow the filament to cool for several minutes before venting thechamber.

Although this is all you need to know to start operating your system, weadvise that you read the manual that comes with the pumping system formore details and maintenance instructions.

!NOTE


Figure 5-1.Pumping station withrotary vane (oil) pumpand diaphragm (dry)pump.


Pressure Reduction System

The M240 pressure reduction system is a vacuum manifold that housesthe Dycor source. It is used to maintain the required low operating pres-sure of the source when sampling from higher pressure (See Figure 5-2).

The M240 pressure reduction system is used in conjunction with theturbomolecular pumping station. This pumping station is intended to beattached to the 4 ½ Conflat flange.

The source is placed on the 2 ¾ Conflat flange opposite the handle of thehigh conductance valve. The 2 ¾ Conflat flange located at the side of thisvalve can be used for attachment to the vacuum system to be sampledand which will be designated as the test chamber.

When open, the high conductance valve allows the source to sampledirectly from the test chamber. This should be done only when the testchamber is pumped down below 10E-5 Torr. Since the vacuum capabilityof the pumping station is better than 10E-8 Torr, the residual gases de-tected will, for the most part, originate from the test chamber. This maynot be the case if measurements are taken when the base pressure withinthe test chamber is below 10E-8 Torr. In this case, a source connecteddirectly to the test chamber should be used.

When the pressure in the test chamber is above 10E-5 Torr, the high con-ductance valve should be tightly closed. This valve is closed by firstrotating the center hex nut fully counter-clockwise and then manuallytightening the large knob clockwise. This should place the poppet over

Figure 5-2.M240 pressurereduction system.


the valve seat but will not seal the valve. Use a 7/8" torque wrench totighten the 7/8" (22 mm) hex nut (turn clockwise). The center nut shouldbe tightened to no more than 45 ft-lb. Use the least amount of torquerequired to achieve a leak-tight seal (a torque of 20 ft-lb. (27 Nt-m) or lessshould seal the valve). The quality of the seal can be determined by usingthe source as a leak checking device.

The M240 pressure reduction system comes with a molecular leak andvalve which bypasses the high conductance valve seal. The molecularleak is located on the gasket of the high pressure side of the two VCRfittings used to mount the bypass. The VCR seal is made by placing thegasket between the sealing glands and turning the female nut ¼ turnbeyond finger tight. The M240 system comes with the seals to one bypassarm already made.

Fittings for a second bypass arm (M142) are blanked off. If a secondmolecular leak is desired the customer must purchase an additionalbypass arm and seal the bypass as described above. Alternatively, thefittings for the second molecular leak can be used to attach an optionalvalve and capillary (M144) to be used for atmospheric sampling or asanother aperture.

The molecular leak bypass is used to reduce the pressure found in the testchamber to a pressure compatible with the operation of the source. Thehigh conductance valve must be closed whenever the test chamberpressure is greater than 10E-5 Torr. The bakeable valve on the bypass armshould be opened slowly since a volume of higher pressure gas is ex-pected to be found between the valve and the molecular leak. Once thisvolume has been evacuated, the pressure in the test chamber, the diam-eter of the molecular leak, and the pumping system speed will determinethe pressure at the source. If this pressure is still too high (above 10E-5

Torr) or if the pressure is too low for your desired sensitivity, then asecond molecular leak can be used. The valve in the first bypass can thenbe closed and the molecular leak in the second bypass can be activated byopening the second bypass valve.

The pressure reduction ratios for different molecular leak aperture diam-eters are given for the pumping station in Figure 5-3.


Although previously used molecular leaks and gaskets have sealed uponreuse, in order to maintain the reliability of the original seal, we recom-mend that new gaskets and molecular leaks be used whenever the bypassarm is resealed after a molecular leak has been changed.

The bypass valves can be used to turn off the molecular leak at any time.This is especially useful when you are concerned that the measurement isinfluenced by the residual gas within the pumping system. The molecularleak can be turned off and a background spectrum can be taken. Thisbackground can then be subtracted from the spectrum taken with themolecular leak open to the system.

You can reduce the background spectrum of the M240, the pumpingsystem and that of the analyzer itself by baking the manifold. This can bedone using either a heating tape or the M107 heating jacket. The elec-trometer must be removed during bakeout. The system will withstand amaximum temperature of 350 °C, but baking for a few hours at a tempera-ture between 100 °C to 200 °C is usually satisfactory. The necessity forbaking and the time and temperature required will vary from applicationto application.

Figure 5-3.Pressure reductionratio for molecularleak aperturediameters.

Aperture Size Pressure Ratio Max. Sample

(Microns) Chamber Pressure (Torr)

2 6.0 x 107 600

5 1.0 x 107 100

10 2.5 x 106 25

20 6.0 x 105 6

50 1.0 x 105 1

100 2.5 x 104 .25

200 6.0 x 103 6.0 x 10-2

500 1.0 x 103 1.0 x 10-2

1000 2.5 x 102 2.5 x 10-3

No Aperture 70 7.0 x 10-4


Rack-Mount and Other Applications (M240)

The M240 pressure reduction system is attached directly to the inlet of theturbomolecular pump using a rotatable 4 ½ Conflat-type flange. Theconfiguration of the turbomolecular pump with respect to the pumpingsystem rack depends upon the user application. If the chamber to besampled is small and supportable from the M240 sampling port, then theturbomolecular pump can remain in the rack and the rack can be placedon a bench or table top. If the test chamber is large and its sampling porthigh above ground level, the turbomolecular pump should be removedfrom the vacuum system rack by removing the four mounting screws atthe bottom of the unit. The M240 and turbomolecular pump can then besupported from the sampling port. In this case, replace the short stainlessline that is used to rough pump the turbomolecular pump by the plasticvacuum hose supplied with the pumping system.

The turbomolecular pump comes with power leads and a vacuum hoselong enough to operate the turbomolecular pump at a distance of up tonine feet from the pumping station. The turbomolecular pump andmanifold are light enough to be supported by a port that calls for a 2 ¾flange. The turbopump can be operated at any angle with respect to thevertical between straight down and horizontal. The pump should not berun in an upside-down position.

The roughing hose should be kept as short as possible so carefully mea-sure the length required and cut the hose to that length. Use the hoseclamps to place KF fittings to the ends of the hose. Then attach the KFfittings to the turbopump and the roughing pump.

Three electrical cables must lead from the turbomolecular pump to thevacuum system rack. These are the turbo power cord , the heater cordand the vent valve cord. It may be convenient to bundle these wirestogether.

The rack can be placed on the floor or other convenient location.!NOTE


Atmospheric Pressure Sampling System

The M250 atmospheric sampling system (Figure 5-4) is used as an atmo-spheric pressure gas inlet system. It requires a pump capable of about 50 l/s pumping speed such as the Dycor turbomolecular pumping station. TheM250 is used to house the Dycor source in the required high vacuumenvironment.

Figure 5-4.M250 pressuresampling system.

The pumping station is attached to the M250 via a 4 ½ Conflat-typeflange using the copper gasket supplied.

The gas inlet is a 1-meter long length of fused silica capillary with aninside diameter of 50 microns (10 microns inside diameter also available).The low conductance of the capillary is used to decrease the sample gaspressure from atmospheric to about E-6 Torr at the quadrupole sensor.

The advantages of the capillary are that gas travels through the system incontinuous laminar flow. The local gas composition along the capillarypath retains the time signature of what happened at the sampling end ofthe capillary. If the capillary becomes clogged, it is only necessary to breakoff a short section from the sampling end of the capillary to be back inoperation.

A bakeable valve is found at the end of the capillary which can be used toturn off the flow of gas to the high vacuum region. The valve can beclosed to look at the system background spectrum. The entire system isbakeable to 350 °C when the electrometer is removed from the system.When looking at gases that will condense at room temperature, the inletcan be heated to a temperature of about 120 °C. This can be done bywrapping the inlet in heating tape or an M107 heating jacket taking carenot to overheat the electrometer.


The capillary is sealed to the sampling system using a graphitized vespelferrule. This ferrule must be tightened to avoid air leaks. The cured softsilicon rubber, found in the black stick-on bumpers, makes an ideal stop-per for the fused silica capillary. Just push the sampling end of the capil-lary into the rubber to make the seal. If there were no previous air leaks inthe system, the capillary can be sealed in this way, the capillary valve isopened, and the source can be used to leak test the ferrule seal. If there isa leak, the peaks at masses 28 and 32 will have the characteristic 4-to-1peak height ratio of nitrogen and oxygen peaks in air.

The capillary is essentially a long narrow tube. Assuming the low pressureend of the capillary will be at a pressure of E-5 Torr or less, that you aresampling from atmospheric pressure, and that you have a linear pressuredrop along the length of the capillary, the pressure within most of thecapillary is a significant fraction of atmospheric pressure. The conditionfor laminar flow is that the mean free path of the molecules in the flow bemuch smaller than the diameter of the flow. Since the mean free path atatmospheric pressure is about 1.0E-6 cm and the capillary diameter is 5-3

cm, laminar flow is expected along the entire length of the capillaryexcept at perhaps the last mm of the capillary.

The Poseuille equation given below should give a good approximation ofthe conductance of the capillary given:

• Gas viscosity of 180 x E-6 poise

• Ñ P is the pressure drop across the capillary in Torr

• P is the mean pressure in the capillary in Torr

• d is the capillary diameter in cm

• L is the capillary length in cm

• Q is the conductance in Torr l/s

Q = ( 182 ∇ P P d4L )Equating the pumping speed for a capillary of 50 microns ID and a lengthof 1 meter to the pressure at the ionizer times the system pumping speed(at this point) of 22 l/s, this gives a pressure at the ionizer of E-6 Torr.

Maintenance & Troubleshooting | 6-1

MAINTENANCE AND TROUBLESHOOTING

This section includes information on:

• maintaining the quadrupole head,

• changing the filament,

• replacing the source

• cleaning the source

• reassembling the source

• cleaning the electron detector.

• troubleshooting the QuadLink

The rest of the analyzer should require no routine maintenance duringnormal use.

Disconnect all power from the analyzer before starting these proce-dures.

Touching any part of the quadrupole head source or mass filter withyour fingers will leave dirt and oil on the parts resulting in contami-nation of the quadrupole head. Use clean plastic/latex gloves whenhandling components.

!WARNING

!CAUTION


Quadrupole Head Maintenance

The quadrupole head requires periodic maintenance. This mainte-nance can be performed by anyone familiar with vacuum systemstandard practices.

The entire head can be disassembled with the exception of the massfilter subassembly. Most parts can be replaced if necessary.

As the analyzer head is used, deposits will form on the source partsand on the mass filter. The lifetime of the source parts varies withapplication, exposure time, and vacuum pressure.

Do not place the mass filter in an ultrasonic cleaner. The filter partscan become loose during ultrasonic cleaning. This will significantlydegrade analyzer performance. A loosened mass filter must be re-placed.

Filaments

Open Source

The Dycor open source contains a dual-wire filament so the analyzer cancontinue to function if one side of the filament burns out. The replace-ment filament comes in a protective container and can easily be replacedin the field.

Equipment required to replace a filament

needle nose pliers,

1/16 hex wrench (supplied by AMETEK/Dycor),

filament assembly kit (supplied by AMETEK/Dycor),

latex gloves - powder-free (optional).

Handling the filament by the shorting tabs on the filament plate willensure against contamination through handling since these tabs willeventually be discarded.

!CAUTION

!NOTE


Removing the QuadLink electrometer from the quadrupolehead

• Disconnect all cables of the electrometer from the power supply toavoid electrical shock.

• After powering down the QuadLink, gently pull straight back on theQuadLink source, without twisting, until it is free of the electrometer.

Replacing the filament

1. Remove the six (6) ¼-28 bolts that hold the nipple to the sourcefeedthrough (Figure 6-1). The feedthrough is the flange containing theeight pins that mate to the electrometer. The nipple is the tube thatcovers the internal components of the source.

2. Remove the nipple from the source. If there is resistance to removingthe nipple, heat the nipple to cause expansion. This allows you toremove the nipple from the source more easily.

3. Remove and discard the copper gasket. DO NOT TRY TO REUSETHE GASKET.

3. To hold the source during disassembly, place the electrometer on a flatsurface and insert the feedthrough of the head into the electrometer.

Removing the old filament

The filament plate is held in place by two (2) stainless steel rods that carrythe current to the filament. Using the hex wrench provided, loosen thetwo small set screws on the barrel connectors that hold these rods inplace, and slide the rods out of the analyzer. Be sure to remove all residualpieces of the old filament.

Installing the new filament

1. Install the new filament being careful not to bend or break the delicatefilament wires. Handle only the shorting tabs on the filament plate.

2. Tighten the set screws that hold the new filament in place.

3. Remove the shorting tabs on the filament by gently bending themback and forth with needle nose pliers until the tabs break at thenotches at their bases.

4. Install a new copper gasket on the feedthrough flange. Be sure itremains centered on the flange.


5. Install the nipple onto the source. Install the six 1/4 x 28 x 1 3/4 boltsto hold the nipple to the source flange. Align the copper gasket withthe knife edges of the mating flanges before tightening. Tighten thebolts using a cross pattern to ensure proper tightening and a gas-tightconnection. There is no recommended torque specification.

6. Check for electrical isolation between the feedthrough pins. Refer toFigure 6-1.

The check should be performed on the pins on the atmosphereside of the source (Figure 6-1).

The pins should be electrically isolated from each other and thenipple. The filament (Pins 2 and 6) should be continuous (approxi-mately 1 ohm) and isolated from the nipple.

Figure 6-1.Quadrupole headpinout, view of flange(atmosphere side).

1

2

8

9

7

6

54

3

Keyw ay

F ilam ent

R epeller G rid

Focus P late

F ilam ent

Source P la te


Replacing the Source

Disassembling the Open Source

Disconnect all power to the analyzer before starting these procedures.

• Remove the filament (see instructions in this chapter).

• Loosen the set screws on the barrel connectors that hold the threeleads coming down from the source elements. This can be done withthe allen wrench provided. The repeller, source and focus plate cannow easily be removed.

• You might find it helpful to mark the keyway location on the sourceside (opposite of pin side) of the feedthrough to reference pin num-bers as you work. Do not mark the area where the copper gasket willbe seated. From the keyway mark you make, the pin numbers are 1through 8 as you move in a counter-clockwise rotation (Figure 6-1).

Discard the old filament, repeller, source and focus plate.

Assembly and installation of the open source

Refer to Figure 6-2.

1. Install the focus plate on Pin 8 of the source feedthrough. Insert thelonger wire into the appropriate hole at the top of the alumina collarand extend it down into the correct barrel connector. (Figure 6-1). Theback surface of the focus plate should rest against the ceramic collar ofthe mass filter. Tighten the barrel connector set screw snugly but donot overtighten.

2. Install the source plate on Pin 1 of the feedthrough. Insert the longwire into the appropriate hole at the top alumina collar and extend itdown into the appropriate barrel connector (Figure 6-1). Install it sothat so that the plate is spaced about 0.1 above the focus plate. Youcan measure the spacing using an appropriately sized wire as a gaugeand separator between the two assemblies. Tighten the connection.

3. Install the repeller on Pin 7 of the feedthrough so that its plate isspaced about 0.1 above the source grid with its long wire in thecorrect barrel connector (Figure 6-1). You can measure the spacingusing an appropriately sized wire as a gauge and separator betweenthe two assemblies. Tighten the connection.

!WARNING


4. Install the filament as described earlier in this chapter.

5. Remove the source from the electrometer/holder.

6. Install the nipple onto the source. Install the six bolts to hold thenipple to the source flange. Align the copper gasket with the knifeedges of the mating flanges before tightening. Tighten the bolts usinga cross pattern to ensure proper tightening and a leak-tight connec-tion. There is no recommended torque specification.

7. Check for electrical isolation between the feedthrough pins. Refer toFigure 6-1.

The check should be performed on the pins on the atmosphereside of the source (Figure 6-1).

The pins should be electrically isolated from each other and thenipple. The filament (Pins 2 and 6) should be continuous (approxi-mately 1 ohm) and isolated from the nipple.

Figure 6-2.Open source.


Cleaning the open source

Because of the delicate nature of the open sources construction, it isimpractical to clean off any deposits that might be on the source. Thesedeposits will cause the source to lose sensitivity and so the source must bereplaced when these deposits occur.

Mass filter

Deposits can form at the entrance to the mass filter rods when they areoperated at high pressures or over a long period of time.

Deposits can sometimes be seen as discolorations on the metal. Insome atmospheres, the rods might be coated with an invisible layerthat will keep the mass filter from operating properly. This will resultin a loss of sensitivity over the full range of the spectrum. If the peaksdisappear at high scan speeds, an insulating layer may have devel-oped on the surface of the rods.

Unless the nature of these discolorations can be identified exactly, theonly sure way of removing them is with a fine abrasive.

The entire quadrupole head assembly must be disassembled to cleanthe rods.

We recommend that the assembly be returned to the factory where therods can be cleaned properly.

!NOTE


Electron Multiplier / V-Stack Detector

The multiplier is immune to up-to-air cycling and routine low-level ionbombardment. However, over time the system will begin to lose gain.When this becomes unacceptable, a new multiplier will restore the origi-nal gain of the system.

Call AMETEK Process Instruments or your local representative toarrange for factory service to replace the multiplier. Because of thecomplexity of the detector flange assembly, we recommend that themultiplier be replaced at the factory.

!NOTE


Troubleshooting the QuadLink

Things to Check First

In many cases, a system failure is not due to a problem with an electroniccomponent, but rather to one of the following:

Operation at too high pressure (greater than 1 x 10-4 Torr).

Improper setting of parameters on a source or calibrate button.

Incorrect or improper cable connection.

Burned out filament.

Shorted-out ion source parts usually resulting from an incorrectfilament or source replacement.

Quick and Easy Solutions

The first step in providing a solution to the problem is performing thefollowing checks.

1. Make sure the quadrupole rod assembly is properly supported withinthe vacuum housing. The housing is either the 5-inch nipple with 2 3/4-inch flanges or a pressure reduction system.

2. Check for leaks in the vacuum system. The system will not workproperly (emission current control) if the vacuum system pressure ishigher than 1 x 10-4 Torr.

3. Make sure all cables are connected properly to the electronic chassis.Make sure the electrometer is fully pushed onto the feedthroughcontacts. Try unplugging the unit and plugging it back in again.

4. Check the continuity between the filament feedthroughs.Although protected, the thoriated iridium filament will eventuallywear out. The best way to determine if this is the case is to check thefilament continuity between the two filament feedthrough Pins 2 and6. See Figure 6-1. If no continuity exists, remove the quadrupole headfrom the vacuum system and replace the filament assembly.

5. After replacing a filament or any other part of the source, check thefeedthroughs for electrical continuity. There should be no shortsbetween any of the feedthroughs (except 2 and 6) or between thefeedthroughs and the metal on the mounting flange. There should becontinuity between the two filament leads.


Localizing the Problem

If the problem persists after going through these steps, you will have tolocalize the problem area. These potential problem areas are:

the monitor

power supply communications

Filament Trip/Overpressure and LEDs

Power Supply Communications

If the unit is turned on but there is a power supply communications errorsignal on the screen, do the following:

1.. Make sure the power supply cable between the controller and thepower supply is plugged in at both ends.

2. Make sure the power switch to the power supply is turned on.

3. If the error message persists, it may be faulty I/O chips in the control-ler. Call the factory or your local representative for help.

Filament Trip/Overpressure and LEDs

1. Check that the filament is turned on. Make sure that the voltage andcurrent are within acceptable ranges by accessing the Status displaywindow in Custom mode of the Dycor System 200 software.

2. Restart the entire system and recheck the filament status and emissioncurrent.

3. If there is no filament current, turn off the instrument, pull the elec-trometer from the analyzer head and check the continuity betweenPins 2 and 6.

4. If the filament is burned out (there is no continuity), open the vacuumsystem and replace the filament assembly.

5. After replacing the filament, bolt the nipple to the flange using thenew copper gasket and check all points on the quadrupole head for


isolation from each other and from the nipple. Only Pins 2 and 6should have continuity. See Figure 6-1.

If the filament checks out OK, and you have emission current, check tosee if you have RF power.

• Check the Status display window in Custom mode of the DycorSystem 200 software to find the value of the RF TUNE parameter. Thevalue should be at 8 or less (lower being optimum). Any other valuesindicate possible RF problems.

• Make sure that the RF FREQ value is at the factory-set value and theRF cable and the electrometer are properly plugged into both thepower supply and the quadrupole head. Recheck the RF TUNE value.

• If the RF TUNE value is 10, unplug the RF cable from the powersupply and check for continuity between the center pin and theoutside shield. If there is no continuity, the cable connector may befaulty. If there is continuity, plug the cable back in.

• For 200 AMU systems, check for a loose potted diode assembly in theelectrometer. Plug the assembly back into the socket if it is loose. If theRF TUNE still reads 0 or 10, call the factory for assistance.

RF Tune Error

Using the Dycor System 2000 software, access the Automatic Calibrationdisplay by clicking on Control on the menu bar and selecting Auto Cali-bration from the drop-down menu. The RF Tune is displayed in the box tothe right of the label. If the value is within specifications, the s

Dycor QuadLink Residual Gas Analyzer - irem senuhv.cheme.cmu.edu/manuals/residualgasanalyzerquadlink...viii | Dycor QuadLink Residual Gas Analyzer Electromagnetic Compatibility (EMC)

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