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LER BPM Issues and Heating Tests

LER BPM Issues and Heating Tests. S. Ecklund, for PEP-II group ( N. Kurita, N. Reeck, S. Smith, R. Johnson, S. Novokhatski, A. Kulikov ). Issues. BPM Absolute Accuracy See G. Yocky, ORM and BBA results BPM failure under high Power conditions June event with vacuum vent Heating formula

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LER BPM Issues and Heating Tests

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  1. LER BPM Issues and Heating Tests S. Ecklund, for PEP-II group ( N. Kurita, N. Reeck, S. Smith, R. Johnson, S. Novokhatski, A. Kulikov )

  2. Issues • BPM Absolute Accuracy • See G. Yocky, ORM and BBA results • BPM failure under high Power conditions • June event with vacuum vent • Heating formula • Lab. measurements • Test buttons • Plan for future running LER BPM issues and heating tests

  3. LER Beam Current and RF Voltage History LER BPM issues and heating tests

  4. LER IR2 chamber Cu (HER) Button Geometry LER BPM issues and heating tests

  5. LER IR2 BPM LER BPM issues and heating tests

  6. LER ARC BPM LER BPM issues and heating tests

  7. Straight BPM • R = 44.45 mm vs. 31 for LER ARC and IR2 • Expect to have ½ the power of LER ARC and IR2 BPM’s LER BPM issues and heating tests

  8. June 2005 Event • Thermocouple T1162QUA indicates R btn falls 14 June LER BPM issues and heating tests

  9. 1162 falls 14 June, beam at (5,-2) LER BPM issues and heating tests

  10. 2022 heats up when 1162 falls LER BPM issues and heating tests

  11. Failed BPM • PR02 1162 • LER outgoing • In HER arc-type duct • Hexagonal Cu • Burned Cable • Lower aisle side • Vac leak through center of coax LER BPM issues and heating tests

  12. LER BPM issues and heating tests

  13. LER BPM issues and heating tests

  14. BPM absorbed Power - Assumptions • dT ~ Power ~ S ib2 f(sz) g(x,y) = Nb ib2 f(sz) g(x,y) • Assume power absorbed at one frequencyf(sz) = exp(- (wrsz/c)2) / exp(-(wrs0/c)2) • Bunch lengthening and scale with Vrf-1/2 sz = sqrt(V0/Vrf) (s0 + si ib) f(sz) = exp(-wr2 (V0/Vrf) ((s0 + si ib) /c)2 ) / exp(-(wrs0/c)2) • Position dependence from calculated signalg(x,y) ~ signal 2 LER BPM issues and heating tests

  15. LER Bunch Lengthening with current (from Sasha Novokhatski) (s0 + si ib) LER BPM issues and heating tests

  16. sz LER BPM issues and heating tests

  17. f(sz) LER BPM issues and heating tests

  18. Nb ib2 f(sz) LER BPM issues and heating tests

  19. g(x,y) from (Steve Smith) LER BPM issues and heating tests

  20. g(x,y) LER BPM issues and heating tests

  21. Lab Test - BPM Heating Experiment • Used weld test chamber with two buttons • Measurement in air • Power applied to button with 25 ohm, 25 W resistor as a heater. Measured current and voltage. • Thermocouples (6) measured: • Heater resistor • Button (2) • BPM collar (normal QUA location) • BPM cable (new RGBY tc) or center pin of connector • Cu Chamber about 1 inch from BPM • Data read with laptop running Matlab code reading serial 485 module (ADAM 4019 ADC) LER BPM issues and heating tests

  22. Lab Test Setup LER BPM issues and heating tests

  23. Lab Test - Run 3 Data LER BPM issues and heating tests

  24. Lab Test - Run 3 Results • Button dT / Collar dT = 15 to 18 • Button dT/Power = 9 to 14 deg C / Watt • T vs. Power not linear • Convective cooling • Radiative cooling LER BPM issues and heating tests

  25. LER BPM issues and heating tests

  26. Summary • No clear threshold for all buttons to fall • Have a formula, but • HOM’s are a complication not included • Assumes f=7 GHz absorption in 15 mm button • Stay below parameters of June failure till buttons are improved in 2006 down. LER BPM issues and heating tests

  27. LER Test New BPM Buttons • Installed 3 new (modified) buttons in LER during October 2005 down • Short on 15 mm button • 7 mm no insert • 7 mm with insert • Feed-through, no button • Compare with normal 15 mm button • Measured • Temperature Rise at collar • Power to Filter-Isolator (FIB) Load Resistor LER BPM issues and heating tests

  28. Shorted 15 mm Button From Nick Reeck LER BPM issues and heating tests

  29. 7 mm – no insert From Nick Reeck LER BPM issues and heating tests

  30. 7 mm button with insert From Nick Reeck LER BPM issues and heating tests

  31. TC Location TC T1022RA,GA,BA,YA were moved to the FIB on BPM units 1022, 1052, 1092, and 1032 LER BPM issues and heating tests

  32. BPM 1052 7 mm, no insert LER BPM issues and heating tests

  33. BPM 1092 7 mm, with insert LER BPM issues and heating tests

  34. Other Normal15 mm LER ARC BPMs1012, dT = 10 deg. F LER BPM issues and heating tests

  35. PR02 2152 New – no button dT = 2 – 3 F LER BPM issues and heating tests

  36. Test Button Results at I = 2.2 A 7 mm button with insert is winner 200 Watt FIB Rating LER BPM issues and heating tests

  37. Conclusion on Button Heating • Run 5B • Limit Current to 3.3 A • Limit LER RF V to 4.5 MV • Limit Orbit offset to 3 mm • Watch TC and raw signal for change • Run 6 • LER ARC – Install new 7 mm buttons • IR2 Straight - bare feed-through or smaller buttons • LER Straight should be OK with ½ power in larger chamber LER BPM issues and heating tests

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