Dec/3/2015WG2 in TTC Meeting Field emission / Radiation in V.T. Kirk

superconducting rf test facility Dec/3/2015WG2 in TTC Meeting 2 Diagnostic tools for radiation in STF  Silicon semiconductor detector  HITACHI ALOKA MAR-781/-782  High/Low sensitivity type  Range : 0.1 – [μSv/h]/0.001 – [mSv/h]  Energy : 50 keV ~ 6 MeV  Target : γ(<10pm), X(1pm – 10nm)  Room temperature, on top plate of cryostat  PIN photo diode  HAMAMATSU S  Spectral response range : 320 – 1100 [nm]  2K (in liquid helium), 22/44 at each iris region MAR-781 S

superconducting rf test facility Dec/3/2015WG2 in TTC Meeting 3 Criteria / Guideline / Processing  Criteria  Exponential growth of radiation level with gradient (F.E. appearance)  Concurrently, lower and lower Q-value (F.E. loaded)  Cavity sometime leads to Quench (F.E. Quench)  ? (F.E. relevant)  Guideline  Try processing  In heavy F.E., when Q 0 <5x10 9 at below 20MV/m, stop the test administratively  <250W for input power in the other region  Processing  Just repeating power rise several times (not special technique!)  When the situation never changes after 10 mins., give up the power rise

superconducting rf test facility Dec/3/2015WG2 in TTC Meeting 4 Success or Degradation ? SuccessFailure Not evaluated

superconducting rf test facility Dec/3/2015WG2 in TTC Meeting 5 Success/Failure rate Definition: Success: after processing, lower X-ray, higher Q 0 and E acc Failure: after processing, higher X-ray, lower Q 0 and E acc Not evaluated: No processing or No X-ray Total samples : 41 tests (MHI-12 – MHI-30) after certification as qualified vendor Success cases : 26 Failure cases : 6 Not evaluated : 9 # of tests w/ F.E. : 32 # of tests w/o F.E. : 9

superconducting rf test facility Dec/3/2015WG2 in TTC Meeting 6 Cure technique for F.E. Automatic iris grinder Grinding iris region is effective technique for F.E. reduction! No iris grinding Iris grinding Manual iris grinder