MTA HPRF Cavity RF Shift Manual v0.1 Sep 11, 2015 Yagmur Torun The latest version of this document should be available at http://mice.iit.edu/mta/shift/hprf/ShiftManual.txt so check for updates there if you suspect it's out of date.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 - for run plan guidance, contact Ben Freemire or Katsuya Yonehara - 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 Peter Lane - for oscilloscope setup issues, contact Ben Freemire - anything else or after hours, contact Yagmur (24 hours a day) Ben Freemire: x4128, freeben@hawk.iit.edu Alexey Kochemirovskiy: x6862, kochemir@fnal.gov Peter Lane: x5555, plane1@hawk.iit.edu 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://dbweb4.fnal.gov:8080/ECL/mta/E/index and log in. Add an entry indicating the start of your shift. This is where all issues 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 mtarflv PC and most of the LabView windows mentioned below are there. On the shelf above the mtarflv monitor, there is an ACNET terminal that shows several real-time plots and parameter listings. These include - gas pressure in the cavity - cavity frequency and temperature There is an ACNET Monitor vi running on the mtarflv3 PC (monitor to the right of mtarflv2) 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=HPRFShift (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, 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) 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 50 kHz) without good reason. The corrections will be small at equilibrium (typically less than 100 Hz). - cavity body (ACNET E:C2TC47, E:C2TC48) and coupler (E:C2TC45, E:C2TC46) temperatures Should be < 28 C and the average level should be varying very slowly (< 1 C/h). If the temperatures look high, you may need to lower the rep rate. - 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 disk on the scopes and the LabVIEW PC at intervals set on this panel. - cavity pickup signal [ 0.7 MV/m gradient] Channel 1 on LeCroy and Tektronix DPO7254 scopes Approximately exponential rise and decay on LabVIEW main panel (NI-Scope Waveforms-DWP). Around 14 us rise time on LabVIEW "Cavity Waveform Analysis" panel [0.08 V] amplitude (Probe Running Average) on LabVIEW main panel. [0.38 V] peak-to-peak amplitude on Tek 7254 scope channel 1. [0.77 V] peak-to-peak amplitude on LeCroy scope channel 1. The following is approximate, Cavity pickup 1 calibration (LeCroy scope): 2.6 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) > 5 Shape of Tektronix 5104 channel 3 (Linac Gallery waveguide), channel 2 on Agilent 7104A (near cavity) and channel 3 on Tektronix 7254 (near cavity) should be similar. - forward power Tektronix 7254 channel 2 (near cavity), Agilent 7104A channel 1 (near cavity), Tektronix 5104 channels 3 (Linac Gallery waveguide) and 1 (klystron output) should look mostly flat during the pulse, some initial droop and modulation is OK. - gas pressure (ACNET) Should be stable, can slowly drift up (due to temperature rise) or down (due to leak). Fast decay (more than a few psi/hour) or sudden loss is cause for concern. - radiation monitors (ACNET) should track average RF power (will go up with gradient and rep rate), typically less than 1 mR/h (E:MTAMR1 to E:MTAMR4), can spike after a spark - light detectors 2 fibers looking into cavity on LeCroy and Tek 7104 scopes' channel 4, both should be quiet - acoustic sensors Make sure the "Spark Flag UDP Updater" VI is running on mtarflv2, 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 65% Current stable at 230A (for 5T) 6) Relax and enjoy your regular routine while keeping an eye on LabVIEW and ACNET plots. Add your observations to the log. 7) Post a shift summary to the log. 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 at least 3 dB before turning RF on again. - In case of a spark (breakdown in the cavity or coupler), 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 a radiation monitor bump. 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 spikes in forward & reflected power just like in a breakdown event but no light and slow decay 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 as fast as the rep rate (currently 2 Hz), check the resolution settings and/or ask for expert help. * List of scope channels: - LeCroy 625Zi (rack LK8-8, top) ch1 Cavity pickup 1 ch2 Unused ch3 Unused ch4 Cavity light (fiber 1) - Tektronix DPO 7254 (rack LK8-8, middle) ch1 Cavity pickup 2 ch2 Forward power (coax near cavity) ch3 Reflected power (coax near cavity) ch4 Cavity light (fiber 2) - Tektronix DPO 7104 (rack LK8-8 bottom) unused - Agilent DSO7104A (rack LK8-7, top) ch1 Forward power (waveguide near cavity) ch2 Reflected power (waveguide near cavity) ch3 Multitrip module gate ch4 Unused - Tektronix TDS 5104 (rack LK8-7, bottom) ch1 Forward power (klystron output) ch2 Reflected power (klystron output) ch3 Forward power (Linac Gallery waveguide) ch4 Reflected power (Linac Gallery waveguide)