RF System for C100 Cryomodule

C100 GDR mode – Original/Modified Tuner Phase noise 25.6 deg rms /14 Hz rms Phase noise 7.5 deg rms /4 Hz rms

C100 Gradient Stability measurement with Audio Analyzer

C100 One Hour Run

C100 Operational Issues –Learned from 2012 Run Liquid level instability –Issues found during commissioning in 2013 Heater configuration Cross talk on Klystron drive cables Tuner related –During operation Field emission causing beam line faults Microphonics related

Heater Configuration –C100 cryomodules have 8 heaters –Only 4 were connected (similar to other zones) Limits how much electric heat can be applied to the module Electric heat was 120 watts and RF heat was close to 230 watts –All 8 heaters were connected to apply ~250 watts of electric heat –One heater power supply Distributed evenly among heaters No control over individual heaters Heat mismatch is possible due to this Will cause liquid level instability in case of a multi cavity trip

Heater Configuration –2L24 with Total heat of ~210 watts –Cavities 6 and 7 have very high detuning (in SEL) Electric Heat 133 W Electric Heat 128 W

Heater Configuration –Had to lower the heat in 2L24 to operate –It can still cause liquid level instabilities after a trip –2L23 on Monday (03/31/2014) –Turned the zone off for 30 minutes for LL to be stable

Heater Configuration –One button recovery is tricky Turn all cavities on in SEL at 10 MV/m Switch to GDR and then ramp to GSET It was necessary for heat balance Still tricky, if cavities need to be bypassed or derated (Field emission, bad tuner etc.)

Cross Talk on Klystron drive cables –Cross talk on heliax cables Causing cavity trips on GMES fault Forward power up to few watts (~15-25) Replaced / re terminated lot of cables Some cases coming from Klystron –Terminated the input to Klystron and cross talk is still there

Tuner Related –Resonance Control Algorithm Was implemented in EPICS Causing overshoot due to non deterministic network latency Implemented via 5 MHz fiber optic Tx/Rx Eliminated the overshoot –Hardware issues Bolts were installed / removed Had to tune few cavities with network analyzer by adjusting the plates manually

Field Emission ZoneEnergy (MeV) (from 2.2 GeV/pass) Notes 1L Two cavities were bypassed with cps problem 1L L L L Cav 6 and 10 MV/m due to FE 2L Cav 9.7 MV/m due to FE 2L L L L

Microphonics Related –Highly visible from R100 performance Quiet during swing and owl Lowered the energy to 56 MeV and scaled the machine to 800 MeV. Had to lower the gradients in 2L24 and 2L25

Summary –Heater Configuration Related Issues Can be solved by adding individual Heater Controls –Cross talk on Klystron drive cables Will inspect and re terminate all the drive cables during summer down –Microphonics issues R100, 2L24 and 2L25 are more susceptible –NL C100s are more stable than SL C100s It would be helpful to understand, if there are any other issues causing this

Summary Questions or Comments ?

C100 RF Team Curt Hovater Trent Allison Rama Bachimanchi George Lahti Clyde Mounts Tomasz Plawski and many others