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CC2 Input Coupler Introduction, Installation, & Processing

CC2 Input Coupler Introduction, Installation, & Processing. Tim Koeth November 16 th , 2005. Input Coupler. Delivers power that develops gradient. Wave guide TE 01 to coaxial TEM mode. Allows D-Q’ing of cavities to match beam loading. Typical Input Coupler. Input Coupler.

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CC2 Input Coupler Introduction, Installation, & Processing

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  1. CC2 Input CouplerIntroduction,Installation,& Processing Tim Koeth November 16th, 2005

  2. Input Coupler • Delivers power that develops gradient Wave guide TE01 to coaxial TEM mode • Allows D-Q’ing of cavities to match beam loading.

  3. Typical Input Coupler

  4. Input Coupler

  5. Input Coupler Installation • Cavity is assembled in Class 10 CR with 80K window and cold bellows. • Cavity is shipped and installed with this portion installed. Note protective cover with RF test port.

  6. Input Coupler Installation • After the cavity was installed in the cryo vessel, we installed the rest of the input coupler.

  7. Input Coupler Installation After the vacuum portion was sealed up, a 150C bake performed to remove water. Ramp ~ 6oC/hr Dwell 24 hrs at 150oC P < 1e-5mbar

  8. Input Coupler Installation • Be certain to protect warm ceramic window during bake. Never place heat tape directly on ceramic !

  9. Input Coupler Installation After bake out, finish Wave Guide Hat installation.

  10. Input Coupler Processing Signals monitored during processing: Not shown: 3 e- pickups PMT looking for sparking in vacuum portion DC Bias TC thermometer Dry N2 (optional) IR thermometer for ceramic Photo Diode for Sparking in atm portion Coupling Adjust Wave Guide from Klystron

  11. Input Coupler Processing • PRESENT DESY S/ H WARE THRESHOLDS: Value FS Conv. Value Software Threshold Hardware Threshold e- 5mA  10V 0.5 ~ 1 V 5 ~ 6 V PMT 1 LUX  10 V 1 ~ 3 V 5 ~ 6 V P.D. ------ ----- 0.2 V Temp Cerm. 70ºC 90ºC In-Cplr Vac 1~2E-7 mbar 1E-5mbar The spark interlock is NOT reset! One must inspect the copper waveguide and warm ceramic window after such an event.

  12. Input Coupler Processing PROCESS 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 to 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 off 2. Wait three minutes 3. The conditioning program tries to reset 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.

  13. Input Coupler Processing • WARM PROCESSING (allows pump to remove contaminants) DESY’s Warm Processing Recipe: Pulse length Pwr Rise/fall Rate Max Power Dwell time 20μS 1kW/min in 30 sec incrm. 1 MW 1 hour 50 μS 1kW/min in 30 sec incrm. 1 MW 1 hour 100 μS 1kW/min in 30 sec incrm. 1 MW 1 hour 200 μS 1kW/min in 30 sec incrm. 1 MW 1 hour 400 μS 1kW/min in 30 sec incrm. 1 MW 1 hour 800 μS 1kW/min in 30 sec incrm. 500 kW 1 hour 1300 μS 1kW/min in 30 sec incrm. 500 kW 1 hour “At the end of the procedure we also do the power sweep for some 2..5 hrs.” – D. Kostine

  14. Input Coupler Processing An example: Multipactoring in “cold” portion during processing of AC68 at DESY e- coupler vacuum e- pickup in cavity vacuum

  15. Input Coupler Processing An example: Power sweep processing during cooldown of AC68 at DESY Vacuum RF Power Temp Temp

  16. Input Coupler Processing • “Cold” Input Coupler Processing (On Cavity Resonance) DESY’s Cold & On Resonance Recipe: Pulse length Pwr Rise/fall Rate Max Power Dwell @ Max Pwr 20μS rectangular 1kW/min (30Ssec) 1 MW 1 hour 50 μS rectangular 1kW/min (30Ssec). 1 MW 1 hour 100 μS rectangular 1kW/min (30Ssec). 1 MW 1 hour 200 μS rectangular 1kW/min (30Ssec). 1 MW 1 hour 400 μS rectangular 1kW/min (30Ssec). 1 MW 1 hour 500+100 μS Flat-top 1kW/min (30Ssec). 1 MW 1 hour 500+200 μS Flat-top 1kW/min (30Ssec). 1 MW 1 hour 500+400 μS Flat-top 1kW/min (30Ssec). 1 MW 1 hour 500+600 μS Flat-top 1kW/min (30Ssec). 500kW 1 hour 500+800 μS Flat-top 1kW/min (30Ssec). 500kW 1 hour One must calculate the Eacc for each pulse and set the maximum power accordingly (in our case maximum. Eacc is about 25MV/m at 500 μS 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 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

  17. Input Coupler Processing It is important to monitor the gradient as not to quench the cavity or exceed rad-safety x-ray limits.

  18. Goals for Nov/Dec ‘05 Warm 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

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