MTA Modular Cavity RF Shift Manual v2.9 Apr 21, 2017 Yagmur Torun The latest version of this document should be available at http://mice.iit.edu/mta/shift/modular/ShiftManual.txt so check for updates there if you suspect it's out of date. This document is a summary of basics, there are training documents at https://indico.fnal.gov/conferenceDisplay.py?confId=9708 with more detail. 0) Get the status of the run from the previous shifter: target gradient, any changes required, recent issues, problems to watch out for, etc. The shift schedule is posted here http://mice.iit.edu/mta/shift/schedule.html so you can find out who should be there before/after you. 1) Put on hearing protection There is a box of ear plugs on the top shelf above the shifter desk 2) In case of problems or questions - for run plan guidance, contact Daniel Bowring - for RF, call Al Moretti (during the day) or Yagmur - for LabView program or DAQ PC issues, contact Dave Peterson - for acoustic sensor DAQ or ACNET monitor, contact Alexey Kochemirovskiy - for oscilloscope setup issues, contact Alexey Kochemirovskiy - anything else, for backup or after hours, contact Yagmur (24 hours a day) Daniel Bowring: x6704, dbowring@fnal.gov Alexey Kochemirovskiy: x6862, kochemir@fnal.gov Al Moretti: x4843, moretti@fnal.gov Dave Peterson: x3073 (voicemail will automatically page him), peterson@fnal.gov Yagmur: x2410, 630-255 1403 (pager), 312-420 5519 (cell), 312-567 3390 (IIT) 3) Start a browser window pointing at the electronic logbook (ECL) http://dbweb0.fnal.gov/ECL/mta/E/index and log in. Add an entry indicating the start of your shift. There is a Start Shift form available from the logbook for this purpose. The logbook is where all the issues, observations and comments should be reported throughout the shift. 4) General monitoring and displays The main LabView program that controls the RF drive and DAQ runs on the mtarflv1 PC and most of the LabView windows mentioned below are there. This PC has 2 monitors stacked vertically. On the shelf next to the upper mtarflv1 monitor, there is an ACNET terminal that shows several real-time plots and parameter listings. These include - vacuum levels in the cavity and nearby - radiation dose rates around the cavity - cavity tuning quality and temperature - average power dissipation (from the water system) - estimated cavity gradient (from RF pickup envelope) There is an ACNET Monitor vi running on the mtarflv3 PC (2nd monitor from the right on shift desk) that periodically checks all relevant ACNET parameters against alarm limits and emits a warning sound (red alert klaxon from Star Trek) when any are outside the normal range. You should check the Summary tab on that window where the offending parameters will be highlighted -- note any issues reported. There is another ACNET monitor script which can be used off-site at this URL http://mice.iit.edu/cgi-bin/mta/acnetize?Config=ModularShift (reload multiple times as needed until all the parameter values are up-to-date) There is a live video feed from cameras in the experimental hall on a monitor next to the ACNET terminal, a blinking red light above the coax Tee indicates the solenoid power supply is on. 5) Checklist (ACNET parameters will be included in the script output above) - number of sparks (main LabVIEW panel titled "NI-Scope Waveforms-DWP") should stay fixed - drive level Make sure "Amplitude Protocol Controller" is running (enabled from main LabVIEW panel) - tuning (main LabVIEW panel) [disabled during multipacting] Mode should be "Phase to Sig Gen". Interval should be small compared to thermal drift time (default is 10 pulses). Do not change span (currently 20 kHz) without good reason. The corrections will be small at equilibrium (typically less than 100 Hz). - cavity & water temperatures (ACNET E:C8CBRT, E:C8EPRT, E:C8RTD1 through E:C8RTD6) Should be < 30 C (86 F) and the average level should be varying very slowly (< 1 C/h). The endplate center-to-edge difference (RTD5 - RTD6) should be < 2.8 C (5 F) If the temperatures look high, check water flow (E:C8CBFL, E:C8EPFL). - waveform capture "NI-Scope WFM Capture" should be enabled on LabVIEW "Waveform Capture Control" panel. You should see the scopes triggered every RF pulse and (if enabled on the same panel) waveforms saved to the disk array and the LabVIEW PC at intervals set on this panel. A set of windows should be open on mtarflv2 for browsing scope capture files. Keep an eye on scope vertical scales which may need to be adjusted to keep up with changes in gradient. - cavity pickup signal [~46 MV/m gradient] Channel 2 on Agilent DSO80304B and channel 1 on the LeCroy scope Approximately exponential rise and decay on LabVIEW main panel (NI-Scope Waveforms-DWP). Around 6/3.4 us rise/decay tau on LabVIEW "Cavity Waveform Analysis" panel [1.62 V] amplitude (Probe Running Average) on LabVIEW main panel. [0.97 V] peak-to-peak amplitude on Agilent 7104 scope channel 4. [1.91 V] peak-to-peak amplitude on LeCroy scope channel 1. [6.28 V] peak-to-peak amplitude on Agilent 80304 scope channel 1. The following are very approximate, Cavity pickup 1 calibration (Agilent 80304 scope ch2): 7.4 MV/m / Vpp Cavity pickup 2 calibration (LeCroy scope ch1): 24.1 MV/m / Vpp Probe Voltage at Peak (LabView): 29 MV/m / V - reflected power Envelope waveforms on main LabVIEW panel should have peaks corresponding to the start and end of cavity fill and dip close to 0 in between. Probe to Refl Ratio in gate on LabVIEW window (Cavity Waveform Analysis) > 2.9 Shape of Agilent 7104 channel 2 (Linac Gallery waveguide), Tek 7104 channel 1 (also Linac Gallery waveguide) and Agilent 80304 channel 3 (near cavity) should be similar. - forward power Agilent 7104 channel 4 (near cavity), Agilent 7104 channel 1 (Linac Gallery waveguide) and Tek 7104 channel 4 (klystron output) should look mostly flat during the pulse, some initial droop and modulation is OK. - vacuum (ACNET) Typically better than 1.5E-7 in the cavity (ion gauge E:SOLIG3, not available when the magnet is on) with RF on and better than 6E-8 in the manifold (ion gauge E:SOLIG1), may increase with gradient and also drift following cavity temperature, may show a large spike during a spark that can take some time before returning to the baseline level. - radiation monitors (ACNET) should track average RF power (will go up with gradient and rep rate), typically less than 2 mR/h (E:MTAMR1 to E:MTAMR4), will spike after a spark - X-ray detectors Small scintillator paddles on channels 2 and 3 of LeCroy. Larger scintillator cubes (upstream) on Tek 7254 channels 1 & 2. NaI detector on Tek 7254 channel 3. Individual PMT pulses will be visible during RF pulse. - light detectors 2 fibers looking into cavity on LeCroy and Agilent 80304 scopes' channel 4, both should be quiet - dark current detector Faraday cup against downstream window, signal on Agilent 80304 channel 1, front end not successfully commissioned yet - acoustic sensors [currently disabled] Make sure the "Spark Flag UDP Updater" VI is running on mtarflv1, the "Breakdown Acoustics Controls" VI is running on mtarflv3 and has the red light labeled "Spark Flag Updater Heartbeat" blinking. - solenoid (if magnetic field is on) LHe level stable around 45%, LN2 level around 60% Current stable at 138A (for 3T) 6) Relax and enjoy your regular routine while keeping an eye on LabVIEW and ACNET plots. Add your observations to the log. There is a Spark? form available from the logbook for logging breakdown events. 7) Post a shift summary to the log. There is an End Shift form available from the logbook for this purpose. Back to 0 (inform next shifter about the status) * How to respond to some of the known problems: - If the RF source trips, call for help, do not try to reset it. Make sure the drive level is down by 3 dB before turning RF on again. - In case of a spark (breakdown in the cavity or couplers), the LabView program will probably wake you up with a loud clang! It will also reduce the drive power by 3 dB and start ramping up again slowly. If you act fast, you can see the waveforms frozen on the scopes as it takes a while to save the snapshots -- you can tell whether the cavity was shorted (pickup signal dropping fast to 0), whether there was any light, etc. You can also look at the ACNET plots which will typically show spikes in vacuum and radiation signals. The LabView log file will have an entry listing details about the pulse including why the program thinks it was a spark (short duration, light signal level above threshold, etc.). Sometimes, the modulator will cut an RF pulse short which may be registered as a spark even though it has nothing to do with the cavity. You can also go to the "Waveform File Reader" window and take a look at the pulse which will show a spike in reflected power just like in a breakdown event but no light and a slow drop in the pickup signal. - If a LabView VI is frozen and you have to exit and restart the whole thing, call for help - If a scope appears frozen, it may be saving waveforms (not all have a visual indicator that a save is in progress) -- check again after a minute or two. If it is not updating the displayed waveforms and flashing the trigger indicator as fast as the rep rate (currently 5 Hz), check the resolution settings and/or ask for expert help. * List of scope channels: - LeCroy 625Zi (rack LK8-8, top) ch1 Cavity pickup 2 ch2 Small plastic scintillator (upstream) ch3 Small plastic scintillator (downstream) ch4 Cavity light (fiber 1) - Agilent DSO80304B (rack LK8-8, middle) ch1 Faraday cup ch2 Cavity pickup 1 ch3 Reflected power (near cavity) ch4 Cavity light (fiber 2) - Tektronix DPO 7104 (rack LK8-8 bottom) ch1 Reflected power (circulator load) ch2 Forward power (circulator load) ch3 Reflected power (klystron output) ch4 Forward power (klystron output) - Agilent DSO7104A (rack LK8-7, top) ch1 Forward power (Linac Gallery waveguide) ch2 Reflected power (Linac Gallery waveguide) ch3 Multitrip module gate ch4 Forward power (near cavity) - Tektronix TDS 5104 (rack LK8-7, bottom) unused - Tektronix DPO 7254 (rack LK8-6) ch1 Plastic scintillator cube (#9) ch2 Plastic scintillator cube (#11) ch3 NaI scintillator ch4 Spark (cavity light) trigger