PEP-II RF System Status and Upgrades

1
PEP-II RF System StatusandUpgrades

• By Vojtech Pacak
• Klystron Department
• PEP-II Machine Advisory Committee Review
• January 18-20 2006

2
Summary

• RF system performance
• Configuration inventory
• Status of selected problems reported in Dec 2004
  MAC meeting
• RF aborts, run 5A/B
• List of leading abort causes
• Klystron status
• Limitations and Spare klystrons
• RF system upgrades
• New HER stations 10 and 11
• Conclusions

3
1) RF System Configuration Runs 4-5-6
Cavity Parameter HER HER HER LER LER LER
Cavity Parameter Jul 2004 Run 4 Oct 2005 PEAK Run 5A PredictedMaximum Run 6 Jul 2004 Run 4 Oct 2005 PEAK Run 5A Predicted Maximum Run 6
RF Voltage/Ring (MV) 16 13.4 18.5 3.8 4.5 5.5
Number of Klystrons 8 9 11 3 4 4
Number of Cavities 26 26 28 6 8 8
Gap Voltage/Cavity (kV) 615 515 661 633 562 687
Dissipated Power/Cavity (kW) 51 36 59 54 42 63
Beam Power/Cavity (kW) 215 242 285 289 2.64 372
Total RF Power/Cavity (kW) 266 278 344 343 306 435
Klystron Power (kW) 940 970 979 757 700 980
Beam Current (A) 1.55 1.74 2.2 2.45 2.94 4.0
Peak Lumin. (1033 cm-2sec-1) 9.213 10.025 15.1 9.213 10.025 15.1
Luminosity predictions assuming ?y, ?y and n
remain fixed.
4
2) Status of Selected Problems Reported in Dec
2004

• Stuck/Slow Tuners
• Found a software bug causing the motor
  controllers to hung up. New software installed in
  SPEAR3. Software will be installed in PEPII.
• SCR Stacks
• Problem of leaking hermetic oil seals of SCRs
  fixed.
• All phasing SCRs work fine.
• Crowbar SCRs develop excessive leakage in
  certain manufacturing lots. Investigated by SLAC
  and EUPEC .
• HER 12-6 Cavity Arcs
• Was traced to arcing in the cavity monitor probe
• A new probe installed in the auxiliary cavity
  probe location fixed the problem.
• HER 8-3 Cavity D Arcs
• Still not understood why the cavity probe signal
  would increase with the increase of cavity
  reflected power.
• Occurrence increases with HER beam current.
• Could be caused by arcing in the coupler box?

5
3) Run 5A Abort Statistics, 4/21/05-10/17/05
Subsystem Faults
HER RF 337
LER RF 151
HER other 69
LER other 232
Average of 4.5 Aborts/Day (2.8 Aborts/Day without
non-RF events) Compared to 2.9/Day for Run 4
6
3) Run 5B Abort Statistics, 10/11/05-1/17/06
Station Faults
her 272
ler 162
LR44 36
HR26 21
HR22 5
HR21 3
HR83 2
HR81 2
HR85 1
HR41 1
LR43 1
LR42 1
Subsystem Faults
HER RF 35
LER RF 38
HER other 272
LER other 162
Average of 5.5 Aborts/Day (0.8 Aborts/Day without
non-RF events) Compared to 2.9/Day for Run 4
7
3) Leading RF caused aborts run 5A/B

• Cav1(2) arcs, Cav1(2) vacuum, 75,36 counts
• Majority (80) in HER 8-1 and HER 12-1.These
  trips have been observed for many years. Cav1 is
  the first the beam enters after the beam pipe
  arcs. The deposit of out gassing debris from the
  arcs into these cavities are believed to be the
  probable cause.
• Typically the operating voltage of these cavities
  is reduced to limit arcing
• Klystron Arc, 41 counts
• About 50 of reported aborts happened during
  testing, (Philips 7,LER 4-3), or during the HV
  processing of the klystron, (Philips 8,HER
  12-6).
• Observed arcing in Philips 7, (LER4-3).
• klystron voltage set lt 73 kV
• HVPS dips or rise, 30 counts
• Few milliseconds voltage reduction or rise leads
  to klystron oscillations. Affected HER 4-1 and
  LER 4-2
• HVPS re-phased
• Drive glitch, LER 4-4, 26 counts
• Station LLRF power supply has been changed.
  Problem may be fixed, but need more confirmation.
• Klystron output RE, HER 12-6, 12 count
• Corrected by adjusting circulator coil current.
• Power dips, 11 counts
• HV reduction in all RF stations in the region.
  Mostly region 8, also observed in region 4.
• Ongoing investigation

8
4) Klystron Issues

• Output power limitation on 4 klystrons
• HER 4-1 (Philips 2)
• Klystron saturation in Philips 2, power limited
  at 850 kW
• Adjusted klystron focus magnetic field, output
  match, circulator bias and waveguide length no
  improvement!
• HER 12-1 (Philips 6)
• Klystron saturation in Philips 6, power limited
  at 750 kW
• Evidence of multipacting
• HER 12-2 (SLAC 6)
• Sideband oscillations 15 MHz, power limited at
  850 kW
• Tuning of the circulator may mitigate the problem
• LER 4-5 (Philips 3)
• Klystron saturation in Philips 3, power limited
  at 850 kW, sideband oscillation 3 MHz
• Hours of Operation
• HER 12-5, HER 4-1, HER 12-3, LER 4-5
• Klystrons Philips s 1, 2, 3 and SLAC 1 near or
  exceeding 50,000 filament hours
• Spare Klystron Status
• Currently Philips 5 is the only spare until SLAC
  8 is tested

9
4) Klystron Manufacturing Schedule
Klystron Start bake Scheduled Test Complete Comment
SLAC 8 completed 3/6/06 Replace Philips 6, HER 12-1
SLAC 7 completed 4/11/06 Replace Philips 1, HER 12-5
SLAC 9 2/23/06 5/17/06 Replace Philips 2, HER 4-1
SLAC 10 4/5/06 6/23/06 New installation, HER 12-4
Philips 4 n/a 8/1/06 Rebuilt at CPI, new installation HER 4-6
Philips 8 n/a 9/15/06 Rebuilt at CPI, replace Philips 3, LER 4-5
SLAC 11 9/17/06 11/16/06 Replace Philips 7, LER 4-3
SLAC 12 11/6/06 1/15/07 Replace Marconi 1, LER 4-4
Courtesy Chris Pearson, KLY
10
4) Klystron Replacement Schedule
Power Limited
Station Q2 2005 Q3 2005 Q4 2005 Q1 2006 Q2 2006 Q3 2006 Q4 2006 gtQ1 2007
LER 4-2 Marconi 4 Marconi 4 Marconi 4 Marconi 4 Marconi 4 Marconi 4 Marconi 4 Marconi 4
LER 4-3 Philips 5 Philips 7 Philips 7 Philips 7 Philips 7 Philips 7 Philips 7 SLAC 11
LER 4-4 Marconi 1 Marconi 1 Marconi 1 Marconi 1 Marconi 1 Marconi 1 Marconi 1 SLAC 12
LER 4-5 Philips 3 Philips 3 Philips 3 Philips 3 Philips 3 Philips 3 Philips 8 Philips 8

HER 4-1 Philips 2 Philips 2 Philips 2 Philips 2 SLAC 9 SLAC 9 SLAC 9 SLAC 9
HER 4-6 N/A N/A N/A N/A N/A Philips 4 Philips 4 Philips 4
HER 8-1 SLAC 5 SLAC 5 SLAC 5 SLAC 5 SLAC 5 SLAC 5 SLAC 5 SLAC 5
HER 8-3 SLAC 3 SLAC 3 SLAC 3 SLAC 3 SLAC 3 SLAC 3 SLAC 3 SLAC 3
HER 8-5 SLAC 4 SLAC 4 SLAC 4 SLAC 4 SLAC 4 SLAC 4 SLAC 4 SLAC 4
HER 12-1 Philips 6 Philips 6 Philips 6 SLAC 8 SLAC 8 SLAC 8 SLAC 8 SLAC 8
HER 12-2 SLAC 6 SLAC 6 SLAC 6 SLAC 6 SLAC 6 SLAC 6 SLAC 6 SLAC 6
HER 12-3 SLAC 1 SLAC 1 SLAC 1 SLAC 1 SLAC 1 SLAC 1 SLAC 1 SLAC 1
HER 12-4 N/A N/A N/A N/A N/A SLAC 10 SLAC 10 SLAC 10
HER 12-5 Philips 1 Philips 1 Philips 1 Philips 1 SLAC 7 SLAC 7 SLAC 7 SLAC 7
HER 12-6 Philips 8 Philips 5 SLAC 2 SLAC 2 SLAC 2 SLAC 2 SLAC 2 SLAC 2
Installation
SLAC Tubes
Run 5B
Run 6
Run 5A
NOW
11
5) PEP-II RF Station Installation
HER Presently Oct 2006 LER Presently Oct 2006
4-1 2 2 4-2 2 2
4-6 n/a 2 4-3 2 2
8-1 4 4 4-4 2 2
8-3 4 4 4-5 2 2
8-5 4 4
12-1 2 2
12-2 2 2
12-3 4 2
12-4 n/a 2
12-5 2 2
12-6 2 2
Install 2006 shutdown
Total Kly/Cav 9/26 11/28
4/8 4/8
12
5) RF Stations Upgrades

• Two New RF stations
• HER10, new station 12-4, split 12-3. shutdown
  2006
• HER11, new station 4-6. shutdown 2006
• Manufacturing/Delivery - major parts
• Resonators.
• Manufacturing under process at ACCEL
• Expected delivery end of May 2006
• Assembly and testing at SLAC May July 2006
• Klystrons.
• SLAC 10 and Philips 4
• Expected delivery May August 2006
• Circulators.
• On site
• Waveguides, Loads.
• Partially Ordered
• Expected delivery end of May 2006
• HVPS and SCRs stacks.
• Ordered

13
6) Conclusions

• For Run 5
• RF system works in general reliably this run!
• RF abort rate averaged 3/day, compared to 2.9/day
  for Run 4.
• Currently 3 power limited klystrons in the HER, 1
  in LER.
• 55 of all RF aborts caused by
• Klystron arcs in LER 4-3 and HER 12-6.
• 4-3 operates with limited voltage, replaced
  klystron in 12-6
• Arcing or vacuum trips of cavity 1/2 in HER 8-1
  and 12-1 stations.
• Lower cavity voltage when arcing may cause the
  problem
• HVPS.
• Ongoing investigation of SCRs failures and
  region power dips
• 3 new SLAC tubes plus 2 repaired Philips
  klystrons by mid of 2006.
• Improved situation with spare klystrons.
• Starting in March, new klystron delivery in every
  5 weeks.
• For Run 6
• Two new HER RF stations, 10-(HR12-3 split) and
  11-(2-cavity HR4-6).
• Up to 3 more new/repaired klystrons ready for
  installation in LER.

14
Acknowledgements

• To all members of the PEP-II RF Systems Taskforce
  from the following SLAC departments
• ARD-A ? LFB Systems
• ESD ? LLRF and Software Systems
• Klystron ? High Power RF and TFB Systems
• PCD ? HVPS Systems
• Specific thanks to Heinz Schwartz, Alan Hill,
  Chris Pearson, Dan Van Winkle and Marc Larrus for
  their input to this presentation.