1. www.delta.uni-dortmund.de/~robert 1 First Experiences in Operating the n.c. HOM-damped Cavity with Beam Robert Heine, Thomas Weis & Group Universität Dortmund Institut für Beschleunigerphysik und Synchrotronstrahlung Maria-Goeppert-Mayer Straße 2 D-44221 Dortmund heine@delta.uni-dortmund.de, weis@delta.uni-dortmund.de

2. www.delta.uni-dortmund.de/~robert 2 Contents Preparations for the in-situ beam test Experiences with the cavity & RF-data Development of pressure, current & lifetime CBM measurements and estimations Summary & Outlook

3. www.delta.uni-dortmund.de/~robert 3 Before reconstructionAfter reconstruction Oct. 2003 until Sep. 2003 RF-Section with DORIS-Cavity Presented at the Karlsruhe meeting

4. www.delta.uni-dortmund.de/~robert 4 Preparations For A „Small“ Test

5. www.delta.uni-dortmund.de/~robert 5 The cavity was preconditioned up to 30 kW (thermal load, CW) at BESSY and delivered to DELTA (17.May `04). Reconditioning within one day (0-30 kW, 5% duty cycle) (02.Jun. `04) 28 kW CW were reached the next day. Vacuum conditioning at 20 kW CW 28.Jun. `04: First beam stored with EU-cavity up to 25 mA 29.Jun. `04: Vacuum limited 60 mA stored 30.Jun. `04: 100 mA stored. 14.Jul. `04: 130 mA stored. (I max of DELTA) The Inserted HOM-damped Cavity

6. www.delta.uni-dortmund.de/~robert 6 RF Data Shuntimpedance from low power measurements: R s = 3.1 M  (EPAC04, F.Marhauser, E.Weihreter) Shuntimpedance from synchrotron frequency & cavity losses: Shuntimpedance from quantum lifetime: f s = 14.872 kHz, P loss = 19.862 kW, f RF = 499.813 MHz, W 0 = 152 keV (SAW)  U RF = 335.67 kV  R s = 2.84 M  ± 10% E = 1.485 GeV, h = 192,  = 0.0053, I = 95-120 mA I = 1 mA, P loss = 4.71 kW  = 1 s W o = 129.4 keV  U RF = 167 kV  R s = 2.96 M  ± 10%

7. www.delta.uni-dortmund.de/~robert 7 RF Data Shuntimpedance from reflected power: Resonator matched @ (77±2) mA I = 77 mA,  c = 1.7 W 0 = 152 keV (SAW) U RF = 335.67 kV  R s = 3.34 M  ± 10%

8. www.delta.uni-dortmund.de/~robert 8 RF Data Quality factor from low power measurements: Q L = 9900 Quality factor from high power measurements (@20kW): Q L = 9200 ± 5%

9. www.delta.uni-dortmund.de/~robert 9 First Weeks of Beam Operation current integrated current lifetime integrated lifetime machine dedicated week 2.36 Ah =71 mAh

10. www.delta.uni-dortmund.de/~robert 10 First Weeks of Beam Operation current integrated current lifetime integrated lifetime user dedicated week 4.78 Ah =174 mAh

11. www.delta.uni-dortmund.de/~robert 11 First Weeks of Beam Operation current integrated current lifetime integrated lifetime user dedicated week 5.63 Ah =227 mAh

12. www.delta.uni-dortmund.de/~robert 12 First Weeks of Beam Operation current integrated current lifetime integrated lifetime user dedicated week 5.65 Ah =245 mAh

13. www.delta.uni-dortmund.de/~robert 13 Pressure Evolution During Operation Pressure dropped nearly one order of magnitude within 4 weeks No multipacting in HOM-dampers with beam

14. www.delta.uni-dortmund.de/~robert 14 First Measurements with the EU-Cavity CBM 55 Threshold at 95 mA. related to a cavity HOM? 27.& 28.Jul. 04 (user week) CBM-No. Ampl [°]

15. www.delta.uni-dortmund.de/~robert 15 Impedance Thresholds of the HOM-damped Cavity in DELTA 130 mA 100 mA CBM65 CBM13 None of the modes maps to CBM 55! MAFIA simulation and mode measurement: F. Marhauser f [MHz] R S [  ] CBM23 CBM105

16. www.delta.uni-dortmund.de/~robert 16 CBM-Measurements with DORIS-Cavity (w. Damper) CBM 53 CBM 65 CBM 42 Filling pattern: 64/192 in 4 Trains of 6 Buckets 15. Sep. 04

17. www.delta.uni-dortmund.de/~robert 17 CBM-Measurements with DORIS-Cavity (w. Damper) CBM 55 Pattern: time 58 Same CBM exited as with EU-Cavity  Pattern induced! Typical structure when CBM 55 excited 16. Sep. 04

18. www.delta.uni-dortmund.de/~robert 18 Summary Successful test with beam @ 1.5 GeV up to 130mA (nominal DELTA current) No cavity induced collective mode found Straight forward RF recommissioning @ DELTA Reasonable development of vacuum pressure No multipacting in HOM-dampers during beam operation Due to removal of cavity no low energy test by now

19. www.delta.uni-dortmund.de/~robert 19 Outlook All HOM-dampers sent to Zanon for revision Strong interest for a second beam test period @ DELTA No final decision by committees yet

20. www.delta.uni-dortmund.de/~robert 20 Thanks to Collaboration partners & DELTA-group

21. www.delta.uni-dortmund.de/~robert 21 END.