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1、CC2 Input CouplerIntroduction,Installation,& ProcessingTim KoethNovember 16th, 2005Input CouplerDelivers power that develops gradientAllows D-Qing of cavities to match beam loading.Wave guide TE01 to coaxial TEM modeTypical Input CouplerInput CouplerInput Coupler InstallationCavity is assembled in C
2、lass 10 CR with 80K window and cold bellows.Cavity is shipped and installed with this portion installed. Note protective cover with RF test port.Input Coupler InstallationAfter the cavity was installed in the cryo vessel, we installed the rest of the input coupler.Input Coupler InstallationAfter the
3、 vacuum portion was sealed up, a 150C bake performed to remove water.Ramp 6oC/hrDwell 24 hrs at 150oCP 1e-5mbarInput Coupler InstallationBe certain to protect warm ceramic window during bake. Never place heat tape directly on ceramic !Input Coupler InstallationAfter bake out, finish Wave Guide Hat i
4、nstallation. Input Coupler ProcessingPMT looking for sparking in vacuum portion TC thermometer IR thermometer for ceramic DC Bias Wave Guide from Klystron Coupling Adjust Dry N2 (optional) Not shown: 3 e- pickups Signals monitored during processing:Photo Diode forSparking in atmportionPRESENT DESY S
5、/ H WARE THRESHOLDS: ValueFS Conv. ValueSoftware ThresholdHardware Threshold e-5mA 10V0.5 1 V5 6 VPMT1 LUX 10 V1 3 V5 6 VP.D. -0.2 V Temp Cerm.70C90CIn-Cplr Vac12E-7 mbar1E-5mbarThe spark interlock is NOT reset! One must inspect the copper waveguide and warm ceramic window after such an event.Input
6、Coupler ProcessingInput Coupler ProcessingPROCESS CONTROL LOGIC:SOFTWARE LOGIC: After each RF pulse, if e-, PMT, light, vacuum, temperature etc signals are higher than the threshold value the power is decreased by one step, if not then the power is increased by one step.HARDWARE LOGIC: In addition t
7、o the software limits used during processing, there are hardware interlocks with greater trip thresholds. The RF is shut off with the “fast switch” when the Hardware Threshold is exceeded. In the event of a Hardware trip: 1. Turn RF off2. Wait three minutes 3. The conditioning program tries to reset
8、 the interlock 4. If reset is successful, RF power setting is set to the minimum (starting) value, and program does fast power increase (10 steps in 10 seconds) to about 90 to 95% of RF power at the event.Input Coupler ProcessingWARM PROCESSING (allows pump to remove contaminants)DESYs Warm Processi
9、ng Recipe:Pulse length Pwr Rise/fall RateMax Power Dwell time20S1kW/min in 30 sec incrm.1 MW1 hour50 S 1kW/min in 30 sec incrm.1 MW1 hour100 S1kW/min in 30 sec incrm.1 MW1 hour200 S1kW/min in 30 sec incrm.1 MW1 hour400 S1kW/min in 30 sec incrm.1 MW1 hour800 S1kW/min in 30 sec incrm.500 kW1 hour1300
10、S1kW/min in 30 sec incrm.500 kW1 hour“At the end of the procedure we also do the power sweep for some 2.5 hrs.” D. KostineInput Coupler Processinge- coupler vacuume- pickup in cavity vacuumAn example: Multipactoring in “cold” portion during processing of AC68 at DESYInput Coupler ProcessingVacuumRF
11、PowerTempTempAn example: Power sweep processing during cooldown of AC68 at DESYInput Coupler ProcessingDESYs Cold & On Resonance Recipe:Pulse length Pwr Rise/fall RateMax Power Dwell Max Pwr20Srectangular1kW/min (30Ssec)1 MW1 hour50 S rectangular1kW/min (30Ssec).1 MW1 hour100 S rectangular1kW/min (3
12、0Ssec).1 MW1 hour200 S rectangular1kW/min (30Ssec).1 MW1 hour400 S rectangular1kW/min (30Ssec).1 MW1 hour500+100 S Flat-top1kW/min (30Ssec).1 MW1 hour500+200 S Flat-top1kW/min (30Ssec).1 MW1 hour500+400 S Flat-top1kW/min (30Ssec).1 MW1 hour500+600 S Flat-top1kW/min (30Ssec).500kW1 hour500+800 S Flat
13、-top1kW/min (30Ssec).500kW1 hourOne must calculate the Eacc for each pulse and set the maximum power accordingly (in our case maximum. Eacc is about 25MV/m at 500 S rise-time and 3e6 coupler Qloaded). “We do also the high power cavity processing, but it is not possible in Your case one needs 1MW at
14、100, 200, 300 us pulses for that purpose and the HPP on the cavity is done for 100,200,300,400,.,1300us pulses up to cavity quench each time.” - D. Kostine“Cold” Input Coupler Processing (On Cavity Resonance)Input Coupler ProcessingIt is important to monitor the gradient as not to quench the cavity or exceed rad-safety x-ray limits. Goals for Nov/Dec 05Warm and Cold processing of the input coupler on CC2 at Meson.Processing done manually !We have begun developing the needed systems automation of input coupler processing: AD, TD, & CD
