1 The Lessons Learned Commissioning a New Klystron & Current Status of the ALS Storage Ring RF System Upgrade Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco Lawrence Berkeley National Laboratory 7 th CWRF 2012 Workshop - BNL, May 7-11, 2012 So Far !
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Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco
7 th CWRF 2012 Workshop - BNL, May 7-11, 2012. The Lessons Learned Commissioning a New Klystron & Current Status of the ALS Storage Ring RF System Upgrade . So Far !. Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco - PowerPoint PPT Presentation
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1
The Lessons Learned Commissioning a New Klystron & Current Status of the ALS Storage
Ring RF System Upgrade
Kenneth Baptiste
Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco
Lawrence Berkeley National Laboratory7th CWRF 2012 Workshop - BNL, May 7-11, 2012
• Mod-Anode Voltage Control during Cathode HVPS Fast Fault (Crowbar) Klystron Recovery - HV Conditioning
• First 2 Months of Operation
2
Phase I: a. Order 3 Thales 300kW klystron, install & operate 1, install 1 off-line, 1 spare
b. Run Philips 330kW klystron until Dec. 2012 c. 2nd 6 week installation shutdown (Jan. 3 – Feb. 14 2012)
d. Run 1st Thales klystron for 500mA User Op’s until 1st Qtr 2013e. Beginning in Spring 2012 disassemble Philips klystron &
assemble 2nd Thales klystron off-linePhase II: a. Order a new HVTR/PS to modify HVPS to 54kV@14A
b. ~8 week installation shutdown (1st Qtr 2013)c. Replace Crowbar/Filter cabinet with new HV Disconnect
Switch/Filter cabinetd. Replace 3-4 ILC’s with PLC control systeme. Run either Thales klystron for 500mA User Op’s until 1 Qtr
2014Phase III: a. Modify waveguide distribution (1 klystron per cavity, full power
klystron test, either klystron driving both cavities)b. Install new digital Low Level RF systemc. Install new RF Signal Diagnostic System
Upgrade Scope
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 3
Magic Tee
CAV
#1
CAV
#2
ALS Storage Ring RF System
Kly. Cir.
Tuner Control
Klystron Efficiency
Loop
50W
Direct Fast Feedback Loop
Ampl. Mod.
Klystron Phase
Phase Detector
Cavity RF Amplitude Loop
Klystron Phase Loop
BEAM
Phase
Attn.
setpoint
setpoint
Slow Beam Phase
SRRF Master Phase
From MO
Control System
LabView App
Modulation Anode
100W
+
-
Tuner Control
Phase Detector
56 kV @ 12 A HVPS
Filter & Crowbar
330 kW
Existing SR RF System
∑
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 4
300 kW
80W
SRRF Upgrade, when Completed
Fil. PS Mod-A
Fil. PS Mod-A
ALS Storage Ring RF System
BEAM
FREF 500MHz
Cont
rol
S yst
em54/50 kV @ 14.5/16 A
HVPS
Filter & Discon-Switch
System PLC Controller: HVPS Intrlks, HVPS
Control, HPA Control
300 kW Klystron
CAV #2Cir.
CAV #1
Tuner Control
Cir.D
AC
ADC
ADC
ADC
BPF
PA DRIVER
BPF
BPF
BPF
/4 /8
ADC
2 WAY SPLITTER BP
F
/10
BPF
FPG
A
2 WAY SPLITTER
IF
IF
IF
500MHz
50 MHz
50 MHz
50 MHz
50 MHz
50 MHz
REF
CELL
FWD
REFL
LO 550 MHz
DA
CAD
CAD
CAD
C
BPF
PA DRIVER
BPF
BPF
BPF
/4 /8
ADC
2 WAY SPLITTER BP
F
/10
BPF
FPG
A IF
IF
IF
500MHz
50 MHz
50 MHz
50 MHz
50 MHz
50 MHz
REF
CELL
FWD
REFL
LO 550 MHz
Digital Board
Digital Board Analog Board
Analog Board
LLRF
Tuner Control
Type N Port
Blank
Type N Port
Blank
400kW 225kW
225kW
200kW
300 kW Klystron
Motorized W/G Switches (5)
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 5
RF Upgrade Layout
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 6
Klystron Site #2
Circulator
Cav 1 & HOM Filter
Cav 2 & HOM Filter
CirculatorLoad
Klystron Site #1
Circulator
CirculatorLoad
HV Dis-Con SW & Filter
Magic-T & Switches
Test Load
Operating Options:Kly #1 to Cav 1 (to 200kW)Kly #1 to both Cavs (300 kW)Kly #2 to Cav 2 (to 200kW)Kly #2 to both Cavs (300 kW)Either Kly to Testload (300 kW)
Flexible Platform• BPM• RF Phase & Amp Monitors• Feedback Systems
Signal Conditioning• Onboard – driven by
packaging• Offboard – modularity,
keep close to cavity
Larry Doolittle: EngineerLow Level RF Controls
Recent Experience• APEX VHF Gun RF
11
Commissioning New Klystron
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 12
Lessons Learned
WaveguideKlystron Output Flange
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 13
Klystron Output Flange• Spec’d flange type Wrong flange
deliveredSent drawings to manufacturer
Spacer
WaveguideCoupler Calibration & Test Load
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 14
FWD & REV Power Coupler• Spec’d coupling factors 0.4dB error
I didn’t check before installing
WR1800 Wedge Water
Load
Test Load• We have (2) 225kW Waveguide Water Wedge Loads
Circulator Reject and Magic-T Reject Placed short on Output Port 1 of Magic-T Placed 45° section and short on Output Port 2 of Magic-T
• The problems Could not increase the cooling flow high enough as we have reduced
flow for normal op’s (~40kW dissipated). VSWR effected as cooling flow increases. Could not get to saturated power.
WaveguideKly Flange, F/R Cplr, Test Load
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 15
Lessons Learned
• Waveguide – The problem with standards is that there are too many to choose from! CHECK, DOUBLE CHECK and the CHECK AGAIN!
• FWD/REV Power Coupler – CHECK, DOUBLE CHECK and the CHECK AGAIN!
• Test Load - If you want to check a new amplifier after delivery and installation make sure you have a rock-solid full power test load. 50Ω ,Stable Match, Adequately Cooled for Full CW power test.
You don’t want any worries about the load when you’re testing new amplifier.
Va = 30 kV, Vripple = 120Vpp !!
Mod-Anode HV PS Ripple
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 16
VfIC load
2
App Note 505• Switching Freq = 40kHz nFCnFC
VkHzmAC stnd 1.2 ,9.1 ,
274024
•Vk = -54kV, Ik = 9A•RFΦ = 9.25°/A Va, 2.5kV/A• Va, 270V/°
•Vk = -50kV, Ik = 7.3A•RFΦ = 8.25°/A Va, 2.7kV/A• Va, 330V/°
•Design Goal = <0.1°• Va-ripple < 27Vpp
Thales TH2161
L
1st Filter Design
CapCharger asDC HVPS40kV @ 12.5mA
VVnFkHz
mAV 7.2 , 16702
6
2st Filter Design,
Va = 30 kV, Vripple = 10Vpp
Power Supply
12.6nF 4.2nF
50kΩ
15MΩ
Va = 20 kV, Vripple = 120Vpp !!
Lessons Learned1. The regulator for the constant current source contributes low freq ripple (a few kHz). Not mentioned in Manufacturer Data Sheet or App Note.2. Va <22kV Not Good for User Beam Operations.3. Fortunate, since Va in range of 24kV – 35kV for User Beam Operations.4. Need a better filter for 70kHz.
& PLC• Current Mode Control Op-Amp Connected Op-Amp inputs to defined V
had unconnected inputs per to properly disable factory config instructions• Delayed Interference Remains Plan to switch to Current Mode Control
ATE 15-50M
Lessons Learned
• Transient due to HVPS Turn-On – Though I was aware of this transient, I didn’t fully appreciate its affect and thought the initial shielding of the electronics and commercial ps was good enough. If we could afford it, I would change the front-end of our HVPS to
have a soft-start.
• Electrostatic Interference/Shielding – I tried to save a few k$ by making a HV Divider and I routed cables away from high E-Field regions. In the end, this cost us over a week in commissioning time! If I could do this again I would schedule transient test time on
new electronics prior to connecting Klystron.
Electrostatic Shielding
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 20
Initial Issue: MA PS Enable Voltage Divider Interference• After ~20 hrs of RF testing with intermittent divider decided to disconnect &
rely on PLC only. Estimated turn off would be 2-3 PLC scan periods (~75ms)• Had a vacuum event in klystron which triggered a Crowbar of Cathode HVPS.• Had 2 more vacuum events in klystron at HV turn-on. MA interception?• Consulted with Thales Field Engineer who offered several solutions
Va = 10 kV, Cath HVPS Crowbar,MA PS Enable via PLC & HV Div,
w/Clamp Diode, < 1us delay
Mod-Anode Voltage ControlDuring Cathode HVPS Crowbar
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 21
MAPower Supply
12.6nF 4.2nF
15MΩ
FilamentPower Supply
CathodePower Supply
+
-
+
-
+-
50kΩ 20kΩ
Hot Deck
MA PS Enable Divider
PLC
F.OCables
Va = 10 kV, Cath HVPS CrowbarMA PS Enable via PLC & HV Div,
w/Clamp Diode, < 1us delay
Va = 10 kV, Cath HVPS Crowbar,MA PS Enable via HV Dic only
~1ms delay, plus ~800ms decay
Va = 10 kV, Cath. HVPS Crowbar,MA PS Enable via PLC only
~100ms delay, plus ~800ms decay
Va = 10 kV, HV Turn-On,MA PS Enable via PLC only
~80ms delay
Va = 10 kV, HV Turn-On,MA PS Enable via HV Div only
~1ms delay
Replaced
Intrlk
Klystron RecoveryHV Conditioning
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 22
Klystron Dis-connected from Cath HVPS, MA HVPS & Fil.• Hi-potted 3-4 hrs, checked vacuum No problems observed• Ran Filament PS Initial turn-on vacuum
current spike
Klystron Re-connected (MA tied to Cathode)• HV Conditioned, checked vacuum Significant outgassing
observed• HV Conditioned for ~60 hrs Several On/Off cycles to condition
Lessons Learned
• Va Control – Incorrectly “Thought” PLC was adequate and MA HVPS would pull down voltage when PS is disabled. It couldn’t, it had no means to accomplish this. Need to measure and “KNOW” before proceeding with “I
THINK...” no matter how much pressure you’re under. Try to listen to other people and understand what they are
saying. Its hard because you are so intent on solving “your” problem.
• HV Conditioning Have good vacuum monitoring of your Klystron as this enables
one to carefully re-condition. Have patience
Va Control during Vk Crowbar
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 23
Operation since Feb. 14, 2012
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 24
Hours on the Klystron• Black Heat 339 (half of nominal filament current)• Standby 2093 (nominal filament current)• HV 2022• Transmit 1823
Klystron Operating Parameters• Vk = -50.4kV Ik = 9.25A• Va = 31.8kV Ia = 3.3mA• Eff = 56.8% Gain = 40.3dB• μP = 1.60