1. 7th 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
Lawrence Berkeley National Laboratory 1 1

2. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Outline
Scope, Schedule & Status of the SRRF Upgrade
Lessons Learned
Waveguide Coupler Calibration, Klystron Flange, Adequate Test Load
Mod-Anode PS Ripple
Cathode HVPS Turn-On Transient
Electrostatic Shielding
Filament PS Stability
Mod-Anode Voltage Control during Cathode HVPS Fast Fault (Crowbar)
Klystron Recovery - HV Conditioning
First 2 Months of Operation
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 2

3. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Upgrade Scope
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 )
d. Run 1st Thales klystron for 500mA User Op’s until 1st Qtr 2013
e. Beginning in Spring 2012 disassemble Philips klystron & assemble 2nd Thales klystron off-line
Phase II: a. Order a new HVTR/PS to modify HVPS to
b. ~8 week installation shutdown (1st Qtr 2013)
c. Replace Crowbar/Filter cabinet with new HV Disconnect Switch/Filter cabinet
d. Replace 3-4 ILC’s with PLC control system
e. Run either Thales klystron for 500mA User Op’s until 1 Qtr 2014
Phase 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 system
c. Install new RF Signal Diagnostic System
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4. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Existing SR RF System
80W
300 kW ∑
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5. SRRF Upgrade, when Completed
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6. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
RF Upgrade Layout
Klystron Site #2
Circulator
Cav 1 & HOM Filter
Cav 2 & HOM Filter
CirculatorLoad
Klystron Site #1
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)
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7. Upgrade Schedule Shutdown Shutdown Shutdown TBD Shutdown TBD Phase I
1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q
Order new Klystrons
Phase I
Install 1st Klystron
Test Kly’s
1 & 2
Run on Existing Philips Klystron
Run new Kly #1
Phase II
Replace Crowbar-Filter w/HV Dis-Con Sw-Filter
Design, Build & Test HV Dis-Con Sw/Filter Cabinet
Addition of Insertion Device(s)
Shutdown
Shutdown
Shutdown TBD
Shutdown TBD
Order new HVTR/PS
Modify HVPS
Phase III
Modify Waveguide Install new LLRF
Design, Build & Test Low Level RF & Controls
Test Kly3
Run on Two new Klystrons 7
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8. Phase I - Status (Completed)
Mod-Anode Cabinet
Klystron Site #2 Completed
PLC
IP PS
Drv Amp
Foc PS
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9. Phase II - Status (in progress)
Klystron Site #1
Filter, HV Dis-Con SW & MA Cabinets
Filter Cabinet
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10. Phase II - Status (in progress)
IGBT Module 4kV, 40A
See Presentation this afternoon...
High Voltage Power Supply for the ALS Storage Ring RF system-Disconnect Switch Status
Slawomir Kwiatkowski
Filter Cabinet
HV Dis-Con Switch Cabinet (24 modules)
HVTR/PS Replacement
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 10

11. Phase III – (in conversation) Low Level RF Plan
Signal Conditioning
Onboard – driven by
packaging
Offboard – modularity,
keep close to cavity
Larry Doolittle: Engineer
Low Level RF Controls
Flexible Platform
BPM
RF Phase & Amp Monitors
Feedback Systems
Why Digital?
No drift
Perfect calibration
Can be accurately
simulated/modeled
Can add remote control & diag
Extra features are cheap, don’t
compromise reliability
Why NOT Digital?
Adds >150 ns latency, can effect
closed loop dynamics
>-150dBc/Hz added noise, ADC
Recent Experience
APEX VHF Gun RF
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12. Commissioning New Klystron
Lessons Learned
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13. Klystron Output Flange 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Waveguide
Klystron Output Flange
Klystron Output Flange
Spec’d flange type Wrong flange delivered
Sent drawings to manufacturer
Spacer
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14. Waveguide Coupler Calibration & 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.
FWD & REV Power Coupler
Spec’d coupling factors 0.4dB error
I didn’t check before installing
WR1800 Wedge Water Load
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 14

15. Waveguide Kly Flange, F/R Cplr, Test Load
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.
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16. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Mod-Anode HV PS Ripple
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 TH2161L
Va = 30 kV, Vripple = 120Vpp !!
Va = 20 kV, Vripple = 120Vpp !!
Cap
Charger as
DC HVPS
12.5mA
App Note 505
Switching Freq = 40kHz
1st Filter Design
Lessons Learned
1. 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.
2st Filter Design,
50kΩ
Power Supply
12.6nF
4.2nF
15MΩ
Va = 30 kV, Vripple = 10Vpp
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17. Cathode HVPS Turn-On Transient
Turn-On Conditions
Klystron connected
HVTR/PS input = 2.5kVAC
HVTR/PS output = -48kV 25ms
-28kV after 250ms Vk
Icap
IPS
HVTR – 12 Pulse Rectifier – L/C Filter
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18. Electrostatic Shielding 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Mod-Anode Hot Deck
Open Frame Hot Deck for visibility & maint Suseptable to E-Fields, Installed shielding panels
Initially installed partially shielded cables Replaced with shielded cables
Unshielded MA HVPS Enable Divider Replaced with compensated divider
PLC FOX
MA PS
Fil PS
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19. Electrostatic Interference
Filament PS – Configurable Linear PS
Output Over-Voltage Protection Disabled & replaced functionality w/PLC
Output Over-Current Protection Disabled & replaced functionality w/Fuse & 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
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20. Electrostatic Shielding 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
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.
7th CWRF 2012 Workshop - BNL, May 7-11, 2012 20

21. Mod-Anode Voltage Control During Cathode HVPS Crowbar
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
Hot Deck +
Va = 10 kV, Cath HVPS Crowbar
MA PS Enable via PLC & HV Div, w/Clamp Diode, < 1us delay
Va = 10 kV, Cath. HVPS Crowbar,
MA PS Enable via PLC only
~100ms delay, plus ~800ms decay
Va = 10 kV, Cath HVPS Crowbar,
MA PS Enable via HV Dic only
~1ms delay, plus ~800ms decay
Filament
Power Supply
Va = 10 kV, Cath HVPS Crowbar,
MA PS Enable via PLC & HV Div,
w/Clamp Diode, < 1us delay
Va = 10 kV, HV Turn-On,
MA PS Enable via HV Div only
~1ms delay
Va = 10 kV, HV Turn-On,
MA PS Enable via PLC only
~80ms delay
PLC - MA
Power Supply
50kΩ
20kΩ +
12.6nF
4.2nF -
15MΩ
Intrlk
MA PS Enable Divider -
Cathode
Power Supply
Replaced
F.O
Cables +
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22. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Klystron Recovery
HV Conditioning
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
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
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23. Va Control during Vk Crowbar
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
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24. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Operation since Feb. 14, 2012
Hours on the Klystron
Black Heat 339 (half of nominal filament current)
Standby (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
Beam Losses
SRRF Faults 6 Crowbar Conduction issues
Magic-T Arc Fast Vacuum Valve RF Intrlk (MPS)
VVT Fan Spurious Crowbar
HV SW Hi-potting -> Spurious Crowbar
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25. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012
Thank you
Acknowledgments:
Max Vinco
Slawomir Kwiatkowski
Jim Julian
Danny Holstein (Thales)
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