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TL4O Matters arising

TL4O Matters arising. 2 nd May 2018. Incoming last week c/o Giulia. Beam characterization at high energy Test chopper performance (nominal pattern) over prolonged period of time. Measure Extinction factor – OASIS/BCT Measure rise/fall time. In theory.

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TL4O Matters arising

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  1. TL4O Matters arising 2nd May 2018

  2. Incoming last week c/o Giulia • Beam characterization at high energy • Test chopper performance (nominal pattern) over prolonged period of time. • Measure • Extinction factor – OASIS/BCT • Measure rise/fall time

  3. In theory • So, the transient time 10% to 90% is max 4.8 ns. The fundamental RF period is 2.8 ns (=1/352.2 MHz), giving a rise time in the order of 2 bunches. • Interesting are also the min pulse length (25 ns) and the min off pulse duration (15 ns).

  4. Chopping patterns • ISOLDE beam foresees 110 turn • Are there issues above 80 turns? Instabilities? • Can we take the longest possible pulse from source? • Minimum chopper off time? • Pulse length to 100 us after head-chop for grids and WS? • No redundancy – what happens if chopper fails etc. • nTOF?

  5. PPM operation • Try PPM copy or LSA cycle copy to virgin cycle • MD5 might have had stuff already there • Note limited working sets in OP • Chopping pattern/timing; magnets • Plus painting & debuncher eventually • Rest is under Inspector for the moment

  6. PPM • I will try the PPM-copy of a virgin cycle.I will PPM-copy MD5 to MD2 which is currently undefined.1. Cloning MD5 to MD_HST_Clone and classified as MD.2. Drive the mismatches to HW. Several errors, but I will put the cycle in the SC.3. Beam in SC. Beam CUT. Several RF faults.Bartosz is coming to help me with debugging the RF.Meanwhile trying to restart some of the equipment with the sequencer. Errors. One issue is to drive and restart being logged as cspop, while one needs to be lin4op. Bartosz protected the equipment with RBAC. Still too many issues, but this helped.Bartosz reset the RF cavities with scripting (even though the sequencer should work identically), but we ended up with the pre-chopper and chopper in faults and could not reset it via knobs (pre-chopper) or sequencer (chopper). When I removed the MD2 from the SC we could reset the equipment. Bartosz does not think the removal is related to the possibility to reset pre-chopper and chopper. Since we are in a hurry to give back beam to Thomas we decided to leave the Linac4 running with MD5. We agreed to redo the test on Wednesday afternoon, if possible.He anyway spotted couple of bugs and wants to fix them before. G-P

  7. Applications

  8. Misc • Debuncher commissioning • Schematic layout still missing – some progress • Logging configuration • anything missing for the moment (choppers?)

  9. Note • No trajectory monitoring • Correction by empirical tweaking of currents • The beam is completely lost between L4L.BCT.1213 and L4L.BCT.3113. Nothing in the laser console. Beam stopper IN. • We tried to visualize the voltage of L4L.NFH.011 on OASIS without success • We have no diagnostic to observe L4L.NFH.014 L4L.NFH.015 L4L.NFH.016The FGC acquisition has a sampling rate of 10 Khz. We should observe a signal of 30kV for L4L.NFH.014 -45kv for L4L.NFH.015 and -35KV for L4L.NFH.016.looking on the screen shot, we have no idea what we are observing!!! • Bad interval defined in the FGC data source for the following devices: • Lots of WD resets during the night - need to follow up. Screenshot of BCT after source and end of Linac -> look into source instability? • Thanks to J.F.C. to bypass the RBAC problem preventing to switch-on the RFQ: After Restarting LASER, I found L4L.RLF.111 and L4L.RLF.121 in fault!After reset and restart, LINAC 4 is alive!

  10. Julie Coupard

  11. Rolf Wegner

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