Vojtech Pacak, PEP-II MAC Review, January PEP-II RF System Status and Upgrades By: Vojtech Pacak Klystron Department PEP-II Machine Advisory Committee Review January

Vojtech Pacak, PEP-II MAC Review, January Summary 1.RF system performance –Configuration inventory 2.Status of selected problems reported in Dec 2004 MAC meeting 3.RF aborts, run 5A/B –List of leading abort causes 4.Klystron status –Limitations and Spare klystrons 5.RF system upgrades –New HER stations 10 and 11 6.Conclusions

Vojtech Pacak, PEP-II MAC Review, January Cavity Parameter HERLER Jul 2004 Run 4 Oct 2005 PEAK Run 5A Predicted Maximum Run 6 Jul 2004 Run 4 Oct 2005 PEAK Run 5A Predicted Maximum Run 6 RF Voltage/Ring (MV) Number of Klystrons Number of Cavities Gap Voltage/Cavity (kV) Dissipated Power/Cavity (kW) Beam Power/Cavity (kW) Total RF Power/Cavity (kW) Klystron Power (kW) Beam Current (A) ) RF System Configuration – Runs * * Luminosity predictions assuming  y,  y * and n remain fixed. Peak Lumin. (10 33 cm -2 sec -1 ) * *

Vojtech Pacak, PEP-II MAC Review, January ) 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 SCR’s fixed. –All phasing SCR’s work fine. –Crowbar SCR’s 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?

Vojtech Pacak, PEP-II MAC Review, January ) Run 5A Abort Statistics, 4/21/05-10/17/05 Average of 4.5 Aborts/Day (2.8 Aborts/Day without non-RF events) Compared to 2.9/Day for Run 4 Courtesy: Dan Van Winkle SubsystemFaults HER RF337 LER RF151 HER other69 LER other232

Vojtech Pacak, PEP-II MAC Review, January ) Run 5B Abort Statistics, 10/11/05-1/17/06 Average of 5.5 Aborts/Day (0.8 Aborts/Day without non-RF events) Compared to 2.9/Day for Run 4 Courtesy: Dan Van Winkle StationFaults her272 ler162 LR4436 HR2621 HR225 HR213 HR832 HR812 HR851 HR411 LR431 LR421 SubsystemFaults HER RF35 LER RF38 HER other272 LER other162

Vojtech Pacak, PEP-II MAC Review, January ) 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 < 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

Vojtech Pacak, PEP-II MAC Review, January ) 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 –It has deformed collector body and is power limited to ~ 600 kW Only after installation of the new SLAC klystrons there will be more Philips tubes as spares

Vojtech Pacak, PEP-II MAC Review, January ) Klystron Manufacturing Schedule KlystronStart bakeScheduled Test Complete Comment SLAC #8completed3/6/06Replace Philips #6, HER 12-1 SLAC #7completed4/11/06Replace Philips #1, HER 12-5 SLAC #92/23/065/17/06Replace Philips #2, HER 4-1 SLAC #104/5/066/23/06New installation, HER 12-4 Philips #4n/a8/1/06Rebuilt at CPI, new installation HER 4-6 Philips #8n/a9/15/06Rebuilt at CPI, replace Philips #3, LER 4-5 SLAC #119/17/0611/16/06Replace Philips #7, LER 4-3 SLAC #1211/6/061/15/07Replace Marconi #1, LER 4-4 Courtesy: Chris Pearson, KLY

Vojtech Pacak, PEP-II MAC Review, January ) Klystron Replacement Schedule StationQ2 2005Q3 2005Q4 2005Q1 2006Q2 2006Q3 2006Q4 2006>Q LER 4-2Marconi 4 LER 4-3Philips 5Philips 7 SLAC 11 LER 4-4Marconi 1 SLAC 12 LER 4-5Philips 3 Philips 8 HER 4-1Philips 2 SLAC 9 HER 4-6N/A Philips 4 HER 8-1SLAC 5 HER 8-3SLAC 3 HER 8-5SLAC 4 HER 12-1Philips 6 SLAC 8 HER 12-2SLAC 6 HER 12-3SLAC 1 HER 12-4N/A SLAC 10 HER 12-5Philips 1 SLAC 7 HER 12-6Philips 8Philips 5SLAC 2 Power Limited Installation Shutdowns Run 5A Run 5BRun 6 SLAC Tubes NOW

Vojtech Pacak, PEP-II MAC Review, January ) PEP-II RF Station Installation HERPresentlyOct 2006LERPresentlyOct n/a n/a Install 2006 shutdown Total Kly/Cav9/2611/28 4/8

Vojtech Pacak, PEP-II MAC Review, January ) RF Stations Upgrades Two New RF stations –HER10, new station 12-4, split 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 SLACMay – July 2006 –Klystrons. SLAC #10 and Philips #4 –Expected delivery May – August 2006 –Circulators. On site –Waveguides, Loads. Partially Ordered –Expected deliveryend of May 2006 –HVPS and SCR’s stacks. Ordered –Expected deliveryMarch 2006

Vojtech Pacak, PEP-II MAC Review, January ) 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 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 SCR’s failures and region power dips 3 new SLAC tubes plus 2 repaired Philips klystrons by mid of 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.

Vojtech Pacak, PEP-II MAC Review, January 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.