1. PEP-II RF System Status and Upgrades
Vojtech Pacak, Heinz Schwarz
Klystron Department
PEP-II Machine Advisory Committee Review
October

2. Summary RF system performance Configuration RF aborts - Run 5
List of leading abort causes
Klystrons
Status of installations and spares
RF system upgrades
New stations HER 12-4 and HER 4-6
Conclusions

3. 1) RF System Configuration – Runs 5A/B - 6*
Cavity Parameter
HER
LER
Oct 2005
PEAK
Run 5A
Aug 2006
Run 5B
PredictedMaximum
Run 6
Predicted Maximum
RF Voltage/Ring (MV)
13.4
15.4
18.5
4.5
4.05
5.5
Number of Klystrons 9 11 4
Number of Cavities 26 28 8
Gap Voltage/Cavity (kV)
515
592
661
562
507
687
Dissipated Power/Cavity (kW) 36 47 59 42 34 63
Beam Power/Cavity (kW)
242
260
285
264
372
Total RF Power/Cavity (kW)
278
308
344
306
294
435
Klystron Power (kW)
970
989
979
700
713
980
Beam Current (A)
1.74
1.875
2.2
2.94
2.90
4.0 *
Number of Bunches (n)
1732
1722
Peak Lumin. (1033 cm-2sec-1)
10.025
12.069
15.1* *
15.1 * *
* Prediction before BPM’s failures
** Luminosity predictions assuming y, y* and n remain fixed.

4. Run 5 Abort Statistics 4/21/05 - 8/18/06
Last event
Count
Stations
Description
03/03/2006
425
ler(4),her(421)
IP Vacuum event with/without radiation
01/27/2006
234
ler(215),her(19)
didt with transverse
09/05/2005 89
multiple
Transverse instability (TFB)
08/14/2006 81
Unknown 66
Cavity 1 arc (RE reported)
07/16/2006 51
Klystron arc
08/17/2006 48
ler(29),her(19)
Longitudinal instability
07/30/2006 43
Power dip (Region 8 or 4)
08/05/2006 41
Slow or stuck tuners
08/16/2006 40
Site Power Dip
Top 10 events account for 1118 faults (58%)
Color code
Non-Rf Aborts
Courtesy: Dan Van Winkle
Station
Faults
HER non Rf
566
LER non Rf
479
HR21
110
LR44 84
LR43 82
HR25 81
HR26 80
HR22
HR83 78
LR42 77
HR81 75
HR41 52
HR85 41
HR23 32
LR45 25
897 RF aborts/483 days
All aborts average per day: 4.0/day
The RF related aborts only: 1.8/day
Compared to 2.9/day for Run 4

5. 2) RF aborts - Run 5 Cav1(2) arcs, 66 counts Klystron Arcs, 51 counts
Majority (~80%) in HER 8-1 and HER 12-1, observed for many years.
Blamed on deposit of out gassing debris from the ring arcs into the first RF cavity, compromising the multipactor coating on the window.
Typically the operating voltage of these cavities is reduced to limit the trips.
Will replace the windows on the first cavities of station 8-1 and 12-1 during the down time
Klystron Arcs, 51 counts
Observed HV arcing in the gun Philips #7, (LER 4-3).
Diagnosed by observing a large drop of klystron perveance.
klystron voltage set < 73 kV
Failed SLAC klystron #6 – due to arcing at the window
Klystron was replaced
Stuck Tuners, 41 counts
A chronic problem increasing during the very hot days.
Tuner stops moving and station trips on high reflected power
Problem analyzed by Claudio Rivetta who found the cause.
The solution will be implemented during the down time.

6. 2) RF aborts - Run 5 continued
Site power dips, 40 counts
230 kV line voltage fluctuation affects all operations
Caused by PG&E, not under our control.
Region 4 and 8 power dips, 43 counts
HV dip in all RF stations in the region, mostly region 8.
More thorough investigation is planned after the 2006 down time.
HVPS
Crowbar SCR’s develop excessive leakage in certain manufacturing lots.
Investigated by SLAC and EUPEC, found problem on ~10% devices.
Solution: regular testing and elimination of the devices prone to leakage

7. 3) Klystron Issues Spare klystron status Klystron failure:
Situation improved since the last January
With new SLAC klystrons coming on line we now have several old Philips klystrons as spares.
Philips #1, over 50,000 filament hours
Philips #2, power limited at ~850 kW, over 50,000 filament hours
Philips #5, deformed collector body and is power limited to ~ 600 kW.
Philips #6, power limited at ~ 750 kW.
Klystron failure:
HER 12-2, SLAC #6 broken output ceramic window – first failure of SLAC made tube in operation
Failure caused by the insufficient tightening of the inner coax bolt that clamps the center conductor contact on the window vacuum side.
Philips klystrons are reaching end of life
Several tubes over 50,000 hours.
LER 4-5, Philips #3, power limited at ~850 kW, sideband oscillation 3 MHz
Region 12 cooling capacity
Increased # of SLAC klystrons need increased cooling supply.
The problem will be addressed during the down time.

8. 4) Klystron Manufacturing Schedule
Start bake
Scheduled Test Complete
Comment
SLAC #8A
completed
3/6/06
HER 12-1, installed Apr 2006, replaced Philips #6.
SLAC #7B
4/11/06
HER 12-2, installed May 2006,replaced SLAC #6 with broken window.
SLAC #9B
5/17/06
HER 4-1, installation 2006 shutdown, replaced Philips #2.
SLAC #10A
6/23/06
HER 12-5, installation 2006 shutdown, replaced Philips #1.
Philips #8C
n/a
10/20/06
HER 4-6, new station installation 2006 shutdown, (klystron rebuilt at CPI), Processing problems – gassy.
Philips #4B
11/10/06
LER replacement, (klystron rebuilt at CPI).
SLAC #11A
12/1/06
HER 12-4, new station installation 2006 shutdown.
SLAC #12A
12/15/06
2/23/07
LER replacement.
SLAC #6B
2/15/07
4/15/07
Courtesy: Chris Pearson, KLY

9. 4) Klystron Replacement Schedule
Shutdowns
Power Limited
Station
Q3 2005
Q4 2005
Q1 2006
Q2 2006
Q3 2006
Q4 2006
>Q1 2007
LER 4-2
Marconi 4
LER 4-3
Philips 7
SLAC 12
LER 4-4
Marconi 1
SLAC 6
LER 4-5
Philips 3
Philips 4
HER 4-1
Philips 2
SLAC 9
HER 4-6
N/A
Philips 8
HER 8-1
SLAC 5
HER 8-3
SLAC 3
HER 8-5
SLAC 4
HER 12-1
Philips 6
SLAC 8
HER 12-2
SLAC 7
HER 12-3
SLAC 1
HER 12-4
SLAC 11
HER 12-5
Philips 1
SLAC 10
HER 12-6
Philips 5
SLAC 2
New
Installation
SLAC Tubes
Run 5A
Run 5B
Run 6
NOW

10. 5) PEP-II RF Station Installation
HER
Presently
Nov 2006
LER
Oct 2006
4-1 2
4-2
4-6
4-3
8-1 4
4-4
8-3
4-5
8-5
12-1
12-2
12-3
12-4
12-5
12-6
Installation
2006
shutdown
Total Kly/Cav
9/26
11/28
4/8

11. 4) RF Stations/Upgrades
New RF stations HER 12-4
split 4-cavity old station HER 12-3
SLAC #11 ready for testing
PEP installation Nov – Dec 2006
New station HER 4-6
2 cavities assembled and currently conditioning
klystron Philips #8 tested
Klystron replacement – total of 4 this year
HER stations 4-1, 12-1, 12-2, 12-5
3 are SLAC klystron, 1 Philips klystron rebuilt at CPI
Installation Apr – Dec 2006

12. Conditioning of the cavity

13. 5) Conclusions PEP RF systems worked reliably this last run!
For Run 5:
PEP RF systems worked reliably this last run!
RF related abort rate average 1.8/day, compared to 2.9/day for Run 4.
Run 5 started with only one spare klystron and four power limited operating klystrons.
Since March, new klystron delivery one every ~ 5 weeks.
Two new SLAC klystrons installed during the run in HER ring.
The most frequent RF aborts:
Arcing and vacuum trips of cavity #1 in stations HER 8-1 and 12-1.
Lowered cavity voltage when arcing
Will replace ceramic windows in cav1 of 8-1 and 12-1
Klystron arcs in LER 4-3 and HER 12-6.
operates with lowered klystron voltage on LER 4-3
replaced klystron in 12-6
Stuck tuners.
Found and implemented solution – (Claudio Rivetta)
For Run 6:
Two new HER RF stations, HER 12-3 split and new 2-cavity HER 4-6.
Only one power limited klystron in LER 4-5 remaining.
Three more new/repaired klystrons will be available for installation in LER.

14. Acknowledgements To all members of the PEP-II RF Systems Taskforce
Specific thanks to Alan Hill, Chris Pearson, Dan Van Winkle, Claudio Rivetta and Marc Larrus for their input to this presentation.