Target Injection/Positioning Update Presented by Ron Petzoldt Neil Alexander 1, Lane Carlson 2, Dan Frey 1, Jonathan Hares 3, Dan Goodin 1, Jeremy Stromsoe.

Target Injection/Positioning Update

Presented by Ron Petzoldt

Neil Alexander1, Lane Carlson2, Dan Frey1, Jonathan Hares3, Dan Goodin1,

Jeremy Stromsoe2, and Emanuil Valmianski1

HAPL Project ReviewSante Fe, NM

April 8-9, 20081. General Atomics2. UCSD3. Kentech Instruments, UK

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Targets are loaded, charged, released, tracked and steered in a vacuum chamber

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±3 kV steeringelectrodes (4 rods)

Mirror

Target loading and charging

Camera

Laser

10 cm

50 cm

90 cm

Target charge measurement

20 µm placement accuracy required

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Recent progress in target injection and positioning (target steering)1.Achieved 13 µm final placement repeatabilty (1) in each transverse direction with solid delrin spheres.

• Centroid Offset X=-3 µm, Y= 6 µm• Designed, built and tested an improved target release

mechanism• Revised LABVIEW code to properly feedback charge to mass

ratio changes to calculated acceleration, velocity and position

2.Achieved 9 µm X & 7 µm Y repeatability (1) with 1 mg shells!

• Centroid Offset X=-1 µm, Y= 4 µm• Improved charge measurement sensitivity

3.Continued electrostatic accelerator work • Procured and tested electrode circuit boards• Designed, fabricated and began testing electronics

and optical components for axial position measurement

• Designed vacuum chamber extension and mounting for accelerator components

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New release mechanism has reduced system vibration during steering

3 points of contactSoft stop

Vibration comparisonStationary targets with mechanism activated

Old New

4 points of contactHard stop

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Example Labview screen shot shows accurate target steering

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Example Labview screen shot shows accurate target steering

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Charge induced voltage overlay

Position deviation overlay

X position

Y position

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We achieved 13 µm target positioning repeatability with solid delrin targets

x = 13 µm y = 13 µm• X offset = -3 µm, Y offset = 6 µm• 23 of 30 in 20 µm radius from aim point• 2 to 4 times better than best previous results…

Solid delrin position errorLast 30 targets 19 Feb 2008

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X position (microns)

Y Position (microns)

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Charge measurement must be more sensitive for low-charge hollow shells

Sensitivity improvements• Larger resistance to ground• Shielding screen• Low pass filter• Increased amplification• Low-leakage op amp

300 mg brass sphere

-2500 V, -0.25 nCoul

1 mg hollow shell-200 V, -0.02 nCoul

Charge measurement

tube input

Output to LABVIEW

Changed to 5

M

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Excellent target positioning repeatability achieved with hollow shells

x = 9 µm y = 7 µm• X offset = -1 µm; Y offset = 4 µm• 27 of 30 in 20 µm radius from aim point• 5 times improvement!!

Last 30 consecutive targets, but we occasionally have had problems• Measured target charge changes, initial target transverse velocity increases• Probably due to static charge in vicinity of target release• Currently correct by venting vacuum and use of polonium strip• UV light is possible solution

Hollow shell position error Last 30 drops 28 March

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Final X µm

Final Y µm

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An electrostatic accelerator provides increased speed and clear tracking beam path

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Electrodes can be printed on circuit

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No Steering

Steering

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Electrodes and crossing detectors were tested

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1 kV standoff between electrodes on single board demonstrated

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IF-E99 LED875-1050 µW

@20 mA

IF-D95Photologic DetectorHigh TTL at 1.0 µW

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We tested the axial position monitoring system

Detector response using NAND and OR gates

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We designed and fabricated circuit boards for LED’s and photo-logic detectors

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Detectors24 boards

LED’s24 boards

NANDOR

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Extension for vacuum chamber designed to support LED’s and detectors

8 boards mounted on each of 6 levels

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Summary of injection/positioning progress

In-flight target steering substantially improved• Achieved 9 µm X & 7 µm Y repeatability (1) with 1 mg

shells!• Centroid Offset X = -1 µm, Y = 4 µm• Low-vibration target release mechanism developed• Improved charge measurement sensitivity• Static charge issues may require more work

Electrostatic accelerator is under construction• Procured and tested electrode circuit boards• Designed, fabricated and began testing electronics and

optical components for axial position measurement• Designed vacuum chamber extension and mounting for

accelerator components