MTA MICE RF Shift Manual v2.2 Mar 23, 2016 Yagmur Torun The latest version of this document should be available at http://mice.iit.edu/mta/shift/mice/ShiftManual.txt so check for updates there if you suspect it's out of date.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/mice/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 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 or Dave Peterson - anything else or after hours, contact Yagmur (24 hours a day) Ben Freemire: x4128, freeben@hawk.iit.edu 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://dbweb0.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 mtarflv2 PC and most of the LabView windows mentioned below are there. Immediately above the mtarflv2 monitor is an ACNET terminal that shows several real-time plots and parameter listings. These include - vacuum levels in the cavity and couplers - radiation dose rates around the vessel - 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 (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=MICEShift (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 Air Tuners". Interval should be small compared to thermal drift time (default is 1 s). The corrections to actuator pressure will be small at equilibrium (typically < 0.01 psi). Due to the high cavity Q, just about any problem will cause a frequency shift that will be manifested as a drift in average actuator pressure. - cavity body temperature (ACNET E:C2TC) Should be < 25 C and the average level should be varying very slowly (< 1 C/h). Downstream face temperature (E:C2TCDS) will be higher than upstream (E:C2TCUS). If the temperatures look high, check water flow (E:C2FL01, E:C2FL03). - 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. Also make sure the "Scope Trigger Monitor and Permit" is running to ensure the capture snapshots on different scopes are in sync (same pulse). - cavity pickup signal [~10.6 MV/m gradient] Linear rise and slower-than-exponential decay on LabVIEW main panel (NI-Scope Waveforms-DWP). Around 65/95 us rise/decay times ("duration") on LabVIEW "Cavity Waveform Analysis" panel. [1.10 V] amplitude (Probe Running Average) on LabVIEW main panel. [2.3 V] amplitude on LeCroy scope channel 1. [2.3 V] amplitude on Tek 7254 scope channel 1. The following are approximate, Cavity pickup calibration (LeCroy scope): 4.6 MV/m / V Envelope detector calibration (LabVIEW probe signal): 9.5 MV/m / V * [Probe peak] - 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 Ratios on LabVIEW window (Cavity Waveform Analysis) or ACNET (E:CrRTIO, E:C2RTIR) > 1.8 (L), 1.9 (R) Shape of Agilent DSO7104A channel 4 (coax at amplifier output), Tektronix DPO 7104 channel 2 (Linac Gallery coax), Tektronix TDS 5104 scope channels 2 (right coupler) and 4 (left coupler) should be similar. - field emission probes Small plastic scintillators on LeCroy channels 2, 3 (on-axis downstream) 1 electron probe on each coupler connected to Agilent DSO80304B scope channels 3 (left), 4 (right) - forward power Agilent DSO7104A channel 3 (tube output coax), Tektronix DPO 7104 channel 1 (Linac Gallery coax), Tektronix TDS 5104 scope channels 1 (right coupler) and 3 (left coupler), has a peculiar shape due to the linear ramps at the beginning and end of the pulse. - vacuum (ACNET) Typically better than 1E-7 in the cavity (ion gauge E:C2CBIG) with RF on, may increase with gradient and also drift following cavity temperature, will show a large spike during a spark that can take some time before returning to the baseline level. Couplers (E:C2CLPR, E:C2CRPR) are typically around 1.5E-6 Vessel (E:SOLIG2) should be stable around 5E-8 When running with the magnetic field on, all the ion gauges will be off except the wall manifold (E:C2WMIG) which has somewhat reduced sensitivity as it's far away. In this case, we have to rely on cold cathode gauges with large baseline values: E:C2CTPR, E:C2FRG1, E:C2CLPR (broken), E:C2CRPR, E:C2ELPR for the cavity top, bottom, left and right couplers and vessel respectively. - radiation monitors (ACNET) should track average RF power (will go up with gradient and rep rate), typically less than 50 uSv/h (mislabeled as mR/h) (E:MTARM1, 3 & 4) (10.6 MV/m, 5 Hz), can spike after a spark - X-ray detectors NaI crystal (near axis far upstream) on Tektronix DPO 7104 scope channel 4. Larger scintillator cubes (upstream) on Agilent DSO80304B channels 1, 2. Individual PMT pulses will be visible during RF pulse. - light detectors 4 fibers looking into cavity on Tek DPO 7254 scope channels 3 and 4, Tek DPO 7104 scope channel 3 and LeCroy scope channel 4. 2 fibers looking at couplers (1 on each) on Agilent DSO7104A scope channels 1, 2 should all be quiet - acoustic sensors The readout for these is not connected at present. - solenoid (if magnetic field is on) LHe level stable around 45%, LN2 level around 65% Current stable at 184A (for 4T) 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 (could be accompanied by a loud pop, clunk, bang or boom depending on the problem), you will see the forward/reflected power and pickup signals go to 0. The modulator should reset by itself and increase the power slowly (typically takes less than a minute). LabView should detect the drop and stop tuning while the power is off. If the modulator does not come back up, call for help. At the present control settings, the air tuners can not respond fast enough if there's a trip while running at high average power. Therefore, as soon as you notice a trip, you should change to fast tuning (mode "Phase to Signal Generator" and interval 1 pulse), wait for the RF signals to get back to full amplitude and the frequency close to the standard value (201.250 MHz), and then switch back to slow tuning (interval 5 pulses, mode "Phase to Air Tuners"). It's best to call for help at this point in order to restore the frequency setting without causing another trip. - 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 a vacuum spike followed by 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 will 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 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 its trigger indicator is not blinking as fast as the rep rate (normally 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 1 ch2 Small plastic scintillator 1 on downstream vessel window (upstream) ch3 Small plastic scintillator 2 on ds vessel window (downstream) ch4 Cavity light (fiber 2) - Agilent DSO80304B ch1 Scintillator cube #9 (upstream, west) ch2 Scintillator cube #11 (upstream, east) ch3 Left coupler field emission probe ch4 Right coupler field emission probe - Tektronix DPO 7104 (rack LK8-8 bottom) ch1 Forward power in coax (Linac Gallery) ch2 Reflected power in coax (Linac Gallery) ch3 Cavity light (fiber 4) ch4 NaI crystal near upstream vessel window - Agilent DSO7104A (rack LK8-7, top) ch1 Light from left coupler ch2 Light from right coupler ch3 Forward power in coax (amplifier output) ch4 Reflected power in coax (amplifier output) - Tektronix TDS 5104 (rack LK8-7, bottom) ch1 Forward power right coupler ch2 Reflected power right ch3 Forward power left ch4 Reflected power left - Tektronix DPO 7254 (rack LK8-6) ch1 Cavity pickup 2 ch2 Scintillator paddle #13 (downstream on-axis) ch3 Cavity light (fiber 1) ch4 Cavity light (fiber 3)