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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

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Kenneth Baptiste Group Members: S. Kwiatkowski (Group Leader) J. Julian, M. Vinco

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  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

  2. 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. 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. 14 2012) • d. Run 1st Thales klystron for 500mA User Op’s until 1stQtr 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 54kV@14A • b. ~8 week installation shutdown (1stQtr 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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 3

  4. Existing SR RF System 80W 300 kW ∑ 4 7th CWRF 2012 Workshop - BNL, May 7-11, 2012

  5. SRRF Upgrade, when Completed 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 5

  6. RF Upgrade Layout Klystron Site #2 HV Dis-Con SW & Filter Klystron Site #1 Magic-T & Switches Circulator 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) Circulator CirculatorLoad CirculatorLoad Cav 2 & HOM Filter Cav 1 & HOM Filter Test Load 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 6

  7. Upgrade Schedule 2010 2011 2012 2013 2014 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q Order new Klystrons Test Kly’s 1 & 2 Install 1st Klystron Phase I Run new Kly #1 Run on Existing Philips Klystron Phase II Replace Crowbar-Filter w/HV Dis-Con Sw-Filter Addition of Insertion Device(s) Design, Build & Test HV Dis-Con Sw/Filter Cabinet Shutdown TBD Shutdown TBD Shutdown Shutdown Modify HVPS Order new HVTR/PS Phase III Modify Waveguide Install new LLRF Design, Build & Test Low Level RF & Controls Test Kly3 Run on Two new Klystrons 7 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 7

  8. Phase I - Status (Completed) Mod-Anode Cabinet Klystron Site #2 Completed PLC IP PS Drv Amp Foc PS 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 8

  9. Phase II - Status (in progress) Klystron Site #1 Filter, HV Dis-Con SW & MA Cabinets Filter Cabinet 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 9

  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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 11

  12. Commissioning New Klystron • Lessons Learned 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 12

  13. Waveguide Klystron Output Flange • Klystron Output Flange • Spec’d flange type Wrong flange delivered • Sent drawings to manufacturer Spacer 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 13

  14. Waveguide Coupler Calibration & Test 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. • 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. 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 15

  16. Mod-Anode HV PS Ripple Cap Charger as DC HVPS 40kV @ 12.5mA 1st Filter Design • App Note 505 • Switching Freq = 40kHz Va = 30 kV, Vripple = 120Vpp !! Va = 20 kV, Vripple = 120Vpp !! 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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 16

  17. Cathode HVPS Turn-On Transient • Turn-On Conditions • Klystron connected • HVTR/PS input = 2.5kVAC • HVTR/PS output = -48kV peak @ 25ms • -28kV after 250ms Vk Icap IPS HVTR – 12 Pulse Rectifier – L/C Filter 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 17

  18. Electrostatic Shielding • 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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 18

  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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 19

  20. Electrostatic Shielding • 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 + Filament Power Supply PLC - 20kΩ 50kΩ MA Power Supply + 12.6nF 4.2nF - 15MΩ Intrlk MA PS Enable Divider - Cathode 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, 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 PLC only ~80ms 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 Replaced F.O Cables + 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 21

  22. Klystron Recovery HV Conditioning • 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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 22

  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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 23

  24. Operation since Feb. 14, 2012 • Hours on the Klystron • Black Heat339 (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 • 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 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 24

  25. Thank you Acknowledgments: Max Vinco Slawomir Kwiatkowski Jim Julian Danny Holstein (Thales) 7th CWRF 2012 Workshop - BNL, May 7-11, 2012 25

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