Anders Mjos wrote:

50 kV stable with less than 1 spark/h during the weekend by RIB obs. Today 57 kV reached, but observed sparking on the resistors of the new HV cable. The cable will be removed to take out the resistors, before reinstalling it. The target hall was locked out, but has now been reopened. This was to avoid sparking to the HV cover.

 EL was brought to 27.5kV.

Conditioning continues today with resistors removed from the HV cable

Tuesday, July 18, 2017, 16:53: BIAS / EZL 50 / 25 kV - no sparks

 Tuesday, July 18, 2017, 16:56: BIAS / EZL 55 / 27.5 kV - one spark

TM3 remained at 55 kV over night. Turbo pumps tripped twice and was restarted and HV recovered by RIB ops. Last recovery brought EZL to 16 kV (not 27.5 kV)

About 25 sparks over 15 h. No sparks for the last 3 h

Wednesday, July 19, 2017, 08:12: EZL to 27.5 kV

Wednesday, July 19, 2017, 08:38: BIAS to 57 kV

Wednesday, July 19, 2017, 08:46: BIAS to 57.5 kV

Wednesday, July 19, 2017, 09:05: BIAS to 59 kV

Wednesday, July 19, 2017, 09:19: BIAS to 60 kV

Wednesday, July 19, 2017, 09:28: EZL to 30 kV

Wednesday, July 19, 2017, 12:25: Heavy sparking. Lowered BIAS to 30 kV

Wednesday, July 19, 2017, 12:37: Increased BIAS again towards 50 kV, but heavy sparking again between 45 and 50 kV. Lowered back to 30 kV

Wednesday, July 19, 2017, 12:40: BIAS at 46 kV

Wednesday, July 19, 2017, 12:42: BIAS at 47 kV

Wednesday, July 19, 2017, 12:44: BIAS at 48 kV

Wednesday, July 19, 2017, 12:48: BIAS at 50 kV

Wednesday, July 19, 2017, 14:50: BIAS at 55 kV after ~2h without sparking at 50 kV

Wednesday, July 19, 2017, 15:12: Sparking. Lowered to 40 kV

Wednesday, July 19, 2017, 16:39: BIAS at 55 kV

Friday, July 21, 2017

Observed top of module inside target hall during HV sparks using crane cameras. No sparks observed, but some faint sound could be heard. Module still sparks at 60 and 55 kV. Have to lower to 40 kV to stop sparking.

Friday, July 21, 2017, 13:25: BIAS / EZL at 50 / 25 kV for without sparking for the last 90 min

Frank and Anders installed lid on TCS and started vacuum system yesterday. To run over the Holidays. Retrieved dose badge from operational storage area. Measured field to be ~ 10 mSv/h at ~9am. Beam went off about 8:30am.

TM4 in conditioning station with no source tray, extraction electrode set to HV bias. Brought up to 30kV over the weekend by ISAC ops with no issues.

BIAS=30kV

EL=15kV

IG1=9.4e-7T

Monday, June 10, 2019, 08:21 : At 32.4kV on bias, EL at 15kV, bias sparked to EL. Every bump of 100V on bias is accompanied by a small vacuum jump and often by a small current increase from ~60uA to 120uA.

* Conditioning station read back and set values are off by 2kV but archive values show this has always been the case. Which to trust? *

Monday, June 10, 2019, 08:54 : Spark while sitting at 38kV on bias, 19kV on EL. Seems to be a spark to EL.  Sitting at 38kV for ~10mins

Monday, June 10, 2019, 09:32 : Sat at 40kV for ~10mins or so, bumping up again.

Monday, June 10, 2019, 09:38 : Spark to EL while sitting at BIAS / EL = 42kV / 20.5kV

Monday, June 10, 2019, 13:57 : Ramped to BIAS / EL = 43 / 21.2. No problems other than what seems to be the usual conditioning station stuff.

 Monday, June 10, 2019, 14:17  : Couple sparks on the way to 48kV, seems to be to the EL.

Monday, June 10, 2019, 14:36 : Up to BIAS/EL = 51/25.5 with no big problems. Will stay here for a couple mins

Ramped down the bias so David could remove the HV cover and lock out the target hall.

Ramped back up to BIAS / EL = 50kV / 26kV quickly with no sparks.

Monday, June 10, 2019, 15:35 : BIAS / EL = 52kV / 26kV

Monday, June 10, 2019, 15:45 : BIAS / EL = 54kV / 28.5kV. It seems that keeping the EL at 1/2 the bias voltage is right on the edge of what is acceptable - the HV seems to be sparking to the EL instead of to ground (either that or the EM interference from the sparks it producing a reaction in the EL...) I will run the EL higher and see if that helps.

Monday, June 10, 2019, 15:57 : Sat at 54kV for > 10mins, will continue up

Monday, June 10, 2019, 16:11 : At BIAS / EL = 55.8kV / 29kV got some sparks, some to EL and some to ground. Back at 55kV.

Monday, June 10, 2019, 16:24 : Sitting at 56kV for a couple mins

Monday, June 10, 2019, 16:37 : Sitting at 56.3kV bias, a spark tripped off the IG1S, which tripped the turbo and shut down all the HV. Back to zero!

Monday, June 10, 2019, 16:59 : TM4 back up to BIAS / EL = 56.1kV / 29.5kV

Monday, June 10, 2019, 17:14 : After 57kV on the bias, things seem to be getting sketchy. The EL voltage and current are a bit jumpy and stepping that voltage up seems to produce a slight spike in the bias current.

Monday, June 10, 2019, 17:31 : At BIAS / EL = 58 / 30.3, looks ok.

Monday, June 10, 2019, 18:11 : Sitting at 59.5kV, could probably push further but will sit here for ~30mins and make sure it is relatively stable. Note 59.5kV set point is really 56.9kV on readout.

Monday, June 10, 2019, 18:18 : some current inconsistencies (not really sparks probably corona discharges...) so went down to 59kV

Monday, June 10, 2019, 18:23 : still getting some sparks at 58kV, going down to 57.5.

Monday, June 10, 2019, 18:37 : went back up to 58, spent 10 mins there but was getting these corona-discharge-type-sparks where the vacuum responds and current is drawn but voltage is maintained. Went down to 57kV, still getting them....

Monday, June 10, 2019, 18:40 : Going down to 56 to see if they stop....

Monday, June 10, 2019, 18:42 : Trying 55 kV now... see attached screenshot for example of sparks

Monday, June 10, 2019, 18:48 : No luck at 55 or 54kV. Going down to BIAS / EL = 50 / 27 for a while to see if this resolves

Monday, June 10, 2019, 19:20 : 30 mins at 50kV, a couple little sparks, but no big deal. Ramping up to 55 and let's see if it is ok.

Monday, June 10, 2019, 19:30 : 55 still not working, going down to 54

Monday, June 10, 2019, 20:16 : Held bias at 54kV for about an hour - dropped it down once to alleviate some sparking. Leaving it at 50kV overnight, ops have instructions to keep an eye on it and shut it off if anything seems strange.

The conditioning station was ramped down overnight and David ramped it back up this morning. Currently trying to get it to sit stable at something higher than 55kV.

Wednesday, June 12, 2019, 08:11 : Sitting at BIAS / EL = 53.9 / 28, 2 sparks to ground, one turned off TP2

Wednesday, June 12, 2019, 08:53 : Been at BIAS / EL = 56 / 28 for >10mins with no real sparks. Will continue up.

Wednesday, June 12, 2019, 08:54 : Spark to EL at 56.1

Wednesday, June 12, 2019, 09:34: Sitting at 55kV for 40 mins. 2 sparks to ground, 1 spark to the EL.

Wednesday, June 12, 2019, 09:49 : Leaving it at 56.6 for a while

Wednesday, June 12, 2019, 09:56 : Either there was a spark to IG1S or there is a vacuum limit that does not accept a 1.2e-6T spike. Everything turned off, but everything seems to still be working.

TM4 was removed from NHC to S_W silo yesterday.  The remove is smooth and successful.

 SMP:MP1 is started with SMP BV1 is opened. SMP is under vacuum for TM4 storage during shut down.

A complete TM3 electrical check at TCS under good vacuum has been done. Pin 14 to 60KV only has 8K ohm on ohmmeter check , and it's about 2Kohm @250V Megga. It's low in resistivity. The pin 14 is for thermocouples only so no big concern.  The rest things are good. See attachments.

Tm3 has been moved  from TCS to silo. The move is successful.

Remotely removed TM2 from S-W silo to SHC . Peter and I did the move. It is successful.

TM2 has been moved from SHC to TCS successfully. Travis and I did the move.

TM2 has been moved to TCS and under good vacuum. TP1/2 work fine.  Electrical check: A to PQ still dead short. B to C @250V 3.8M which is ok still . We knew these two things before. Other things are good. Vacuum: air to vacuum seals on TM2 service cap are good. Helium pressure test on all water lines are good. HS line no target so can't be tested. But We did helium pressure test on each target change so it's fine.

TM4 electrical check at SMP(vented) without target: PQ is dead short to RU. PQRU to 60kv bias,750Kohm at250V. other things are good. Notes: In attachment files all hand writing and circled TM2 should be TM4.  the results are measured on TM4 not TM2.

TM2 has been moved from TCS to west-south silo. Travis and I did the job. The move is successful.

 After discussion with Friedhelm it was decided to continue trying to condition the module today before moving it tomorrow. The voltage was quickly raised until 40 kV where it was left for ~30 minutes. Sparking was minimal. It was then slowly raised to 44.3 kV it held this voltage for ~8 minutes when the current started to climb (remained below 200uA as set as a limit in previous tesing). There was also sparking at this point. This continued for ~2.5 minutes until once again the water resistivity sensor tripped again. It appears that there is a~ 44kV limit on TM3. Attached is the data. I will present all of the data to the group tomorrow showing the results of multiple testing.

TM3 has been moved from the south hot cell to the conditioning station. David and I completed the move. All went well.

 A high voltage test was completed on a target free TM1 in the conditioning station. Only the turbo pumps on the target module were operational due to phase 2 construction. Testing started at 2:51PM with the following vacuum gauge readings, 1.6 x 10^-6 Diagnostics Box, 7.4 x 10^-7 Service Cap, 2.0 x 10^-6 Containment Box. Voltage was increased ~3kV at a time every minute until 21 kV was reached with a current of 0 uA. Voltage was then increased in ~1.5kV steps every 2 minutes until 30 kV was reach at a current of 60uA. This was held for 7 minutes until a spark occurred and the current spiked to 300uA and the voltage dropped. The voltage was dropped back to zero. The vacuum gauges had increased and read the following  1.6 x 10^-6 Diagnostics Box, 7.9 x 10^-7 Service Cap, 2.1 x 10^-6 Containment Box. Testing was restarted 2 minutes later (the vacuum gauges were still recovering for ~ another 2 minutes) and the voltage was quickly increased to 24kV reaching a current of 100uA. at 3:22 The current then fluxuated but trended up for the next 12 minutes peaking at a total current of 240uA. After this point the current started deceasing, at 3:41 the testing was concluded and the average current was ~170uA. The vacuum gauge readings were 1.6 x 10^-6 Diagnostics Box, 7.4 x 10^-7 Service Cap, 2.0 x 10^-6 Containment Box. It was deemed that this is "not ideal but good enough" to put the target on.  The maximum known required voltage will be ~22kV for Berillium which TM1 should be capable of providing.

TM4 has been moved from the South West silo to the South Hot Cell. New source tray, no target.