Tuesday, January 07, 2025, 16:00 -  Target assembly installed in test stand. electrical connections assessed:

Prior to installation:  oven and cathode isolated from heatshield. no shorts

After installation:  Oven and Cathode 35kΩ from HVC. 

Tuesday, January 07, 2025, 16:05  -  pumping down to rough vacuum

Tuesday, January 07, 2025, 16:45  TP1B on.      TP1A on.  Pumping down

Prior to proceeding, ensure that ALL water cooling is turned on, as it was all drained and empty for the past 2 weeks.

Tuesday, January 07, 2025, 17:10   Beam line TP1 and TP2 on. 

Wednesday, January 08, 2025, 09:01    chamber pressure at 1.0E-6 T,  beamline pressure at 3.7E-7 T

 Wednesday, January 08, 2025, 10:32 - water cooling all on. no effect on vacuum pressure. 

Wednesday, January 08, 2025, 10:33    - Increased argon pressure in the gas line has no effect on vacuum pressure. it is registered on the pressure gauge at feedthrough.- 

  - However, roughing pump doesn't seem to be venting the argon gas line. I disconnected the copper line to the venting valve to confirm pump activity. - no activity detectable. 

- removed pump from assembly. switching on by itself shows no evidence of pump functionality. When on, pump is heating to very hot temperatures. I've emailed Edi at vacuum group to investigate further.

Wednesday, January 08, 2025, 15:02   - Vacuum group says that the pump is dead. We can replace it if we'd like, but i've created a temporary solution by connecting the argon venting valve to the backing pumps. For the sake of being careful (although this may be overly cautious), we must avoid opening this venting valve without first isolating the connection from the turbo pumps via closing TSG:PV1

Wednesday, January 08, 2025, 15:04  ramping up COIL to ensure conditioning against outgassing later.  vacuum appears to be stabilizing below 2e-6 T

Wednesday, January 08, 2025, 16:32   vacuum recovered, beginning to heat at 1A/30s up to 580A/230A    TGHT/TBHT

Wednesday, January 08, 2025, 22:32   with COIL on, the vacuum pressure increased to ~2.2E-6 T before beginning to recover, leaving on to encourage vacuum recovery.

Thursday, January 09, 2025, 08:27 Vacuum at 1.0E-6 T.  COIL off.

Thursday, January 09, 2025, 10:15   Argon gas line at 0.5 bar.a

Thursday, January 09, 2025, 10:56   increasing BIAS/EE/EZL  to 30/1.5/13 kV 

Thursday, January 09, 2025, 11:19    turning on optics elements. TMS:Q2 is timed out and possibly unalive. - must be investigated

Thursday, January 09, 2025, 12:38  HV at 30kV. monitoring for spark activity 

Thursday, January 09, 2025, 12:53  over 15 minutes, there was just one possible spark.  I see also that TPS:Q2 (quadrupole prior to FC0) seems to be half-down. i can't seem to get it to stop timing out and recharge. must investigate further

after investigating further and attempting to reset/reconfigure. I tried power cycling the canbus controller as well. In the end, controls group determined that this controller needed to be replaced.

 Thursday, January 09, 2025, 14:34   all optics set.  setting COIL CATHODE to 40A 120V.   CATHODE is leaking 0 current. (0.000 mA readback).  

Thursday, January 09, 2025, 14:37   reading 2.91e-8A at FC0 . found Argon peak at 40 exactly. MB1 current 96.4561 A

Thursday, January 09, 2025, 14:42 using COIL CATHODE scan program to optimize. (data file measure_id=9106)  A local maximum was identified at 140V with 40A coil current. However, a short seems to show up when the cathode voltage reaches ~130V. it lets through only ~10mA at 130 and then will release up to at least 100mA at 140V.

As time passes, the sustained voltage drops over time, given a current limit of 100mA. it dropped to ~50V. On subsequent increases of the power supply, current begins leaking through at ~65V. 

Given this, I will continue (while monitoring the cathode power supply) with a cathode coil of 50V 90A.

Thursday, January 09, 2025, 15:28  FC0 = 2.21 e-8 A.    FC6 at 3.21e-10A   RPM taken for all 4.

Thursday, January 09, 2025, 16:04   mass scan complete  -  2025_01_09-16_01 FEBIAD no retainer 1.txt CATHODE voltage was stable at 50V throughout.

 Thursday, January 09, 2025, 16:07  decreasing BIAS/EE/EZL to 0, 0, 0

 Friday, January 10, 2025, 09:09    ramping BIAS/EE/EZL  to 30/1.5/13 kV 

Friday, January 10, 2025, 11:51 Increasing COIL and CATHODE to 90A and 50V (was able to ramp cathode up to 100V before seeing current loss)

Friday, January 10, 2025, 11:53   FC0 = 1.7e-8 A.    FC6 = 4.9e-10 A    wire scans taken.

Friday, January 10, 2025, 12:00     Beginning mass scan with COIL CATHODE at 90A 50V   - 2025_01_10-12_28 FEBIAD no retainer 2.txt

Friday, January 10, 2025, 12:28   decreasing BIAS/EE/EZL to 0, 0, 0

 Friday, January 10, 2025, 13:15   gas inflow OFF (at rough vacuum pressure). Ramping up again BIAS/EE/EZL  to 30/1.5/13 kV 

Friday, January 10, 2025, 14:27   FC0 = 1.22e-8A.   FC6 = 2.93e-12A  (at 40) .   mass scan taken  = 2025_01_10-14_18 FEBIAD no retainer 3 argon off.txt     wire scans taken.

Friday, January 10, 2025, 14:28   TGHT TBHT cooling to 0A 0A at 1A/30s
 

Monday, January 13, 2025, 11:00   testing cathode isolation on cold target by ramping up cathode voltage until breakdown.   At 120V, CATHODE current is 2.4mA. (125V, 8.5mA), at 130V, current limiting and dropping voltage.

 Monday, January 13, 2025, 11:10   power supplies off. Winding down turbo pumps for chamber evac

Monday, January 13, 2025, 13:07   venting 

Test piece installed with Sam, Aaron and Alexander. Ended up shimming the support stand (middle foot) since it seemed to be bowing a bit and distorting the gap between the containment box stand-in piece and the service tray piece. We should measure the gaps when testing is done with the same configuration. Installation was not too hard, installed the whole thing as one piece. Had to remove the middle foot on the long side to get it through the door but otherwise no problems.

Test stand re-wired for HV testing. Wire hooked up to test piece by pinching between two tubes. Verified GND and HV continuity.

Thursday, December 03, 2020, 15:54 :

Got sign off from John Chow to run the system, though the nylon insulator was not ready when he came by. But we went over everything together.

Installed blue nylon insulator with all vacuum surfaces cleaned at least with methanol. No NPT fitting or tube installed, just testing service cap.

Thursday, December 03, 2020, 17:31 :

Tested voltage on the blue nylon insulator up to 75kV, left it at 75 for ~30mins. No sparking, no current drawn except occasionally when changing voltage and only ~1uA then.

Cleaned (but not very well...) the NPT fitting, copper tube, alligator clip and section of copper wire and installed these in the vacuum chamber. Will pump down overnight for testing tomorrow.

See attached photos for insulator setup and wire inside vacuum chamber.

Wednesday, December 16, 2020, 10:30 (Carla) :

Started ramping up about 45 mins ago, now at 50kV with no issues. No sparking, occasional current draw to get to the next voltage step. Test piece is no longer drawing any current, as opposed to yesterday when it was drawing around 4uA at this point. Trace left on insulator must have partially evaporated in the vacuum overnight.

Wednesday, December 16, 2020, 10:34 :

Starting to draw some current at 50.5kV. Drawing 4uA at 55kV.

Wednesday, December 16, 2020, 10:51 :

Back up to 60kV, no sparks so far and no issues, though it is still drawing 5uA of current, as it was yesterday.

Wednesday, December 16, 2020, 12:28 (Alexander)

No sparks at 60 kV for 1.5 hours. Starting voltage increases again at 250 V increments. Currently limiting current to 6 uA. Current draw is 4 uA.

Wednesday, December 16, 2020, 13:20

63 kV. Appears current limited, increased current limit to 7 uA. First spark was at 62.75 kV.

63.25 kV. Seems current limited again but eventually reached a stable voltage after a minute. Increased current limit to 8 uA for next voltage increase.

63.5 kV. Spark.

63.75 kV. Unstable trying to reach voltage, appears current limited. Small spark followed by a big one on the rise of the previous. Second one activated something pneumatic nearby. Reduced voltage by 250 V. Looked at vacuum system but nothing abnormal.

63.5 kV. Spark, not recorded on GoPro. Stable after 5 minutes. Continuing.

63.75 kV. No longer current limited and reached voltage stably. Dumped data.

Wednesday, December 16, 2020, 14:02

64.5 kV. May be current limited again, took over a minute to reach stable voltage.

Note: None of the sparks recorded today so far have produced a response in the vacuum, which is holding steady at 1e-6 Torr.

65 kV. Smooth transition to it. Drawing 5 uA.

65.25 kV. Spark after voltage instability and current draw at 8 uA limit. Moved the Faraday cup, which made a sound. This is the sound I heard earlier. Lower current draw after the spark, back at 5 uA.

Wednesday, December 16, 2020, 15:20

Stable at 65.25 for an hour, no sparks.

Spark at 66 kV. Current limited and unstable voltage for about 2 minutes afterwards, then stable with current back to 6 uA.

Spark at 66.5 kV after some voltage instability and current limiting. Afterwards current and voltage returned to stability.

67 kV, two sparks, one right after the other. The second produced a bump in the vacuum. Reduced voltage. Brought back up easily; current stable at 5 uA.

67.25 kV. Spark. No instability preceding it for a good 20 seconds.

67.5 kV. Spark. Instability before, none after.

Wednesday, December 16, 2020, 16:08

68 kV. Spark. Instability before, none after. Vacuum dropped about 20 seconds after recovering. Current also dropped to 4 mA, at about the same time the vacuum dropped. Dropping current limit to 7 uA.

68.25 kV. Vacuum jumped back up to earlier values and then an eventual spark after some instability. Returned to stability after spark. Current now at 5 uA.

68.75 kV. Spark.

69 kV. Carla went to look inside. Saw some small sparks towards the back between the HV sheath and GND sheath in the small gap side. Very little registered in EPICS, though. Just a couple jumps in current and small dips in voltage. Not visible in GoPro footage.

Wednesday, December 16, 2020, 16:38

69.25 kV. Two sparks. Stable after second. Third spark. Reviewed GoPro footage because third spark was suspicious. Appears on video but not near or on the prototype. Could have been the wire. Dumped data.

69.75 kV. Some instability paired with a change in vacuum for the same duration.

70 kV. Carla went to look. Nothing visible on the StripTool but Carla said she saw small sparks towards the back. Going to leave here for 20 minutes before raising again.

Wednesday, December 16, 2020, 17:12

Held for 20 minutes at 70 kV with no action. Starting voltage increases again.

70.25 kV. Two and a half minutes of voltage instability, raised vacuum, and limited current. All of them stopped and started at the same time. Seems like conditioning to me.

70.5 kV. Carla saw two very faint sparks towards the back on the small gap side. Little appeared in EPICS. Spark followed maybe a minute and a half later. 2nd spark four minutes after that. Before and between those sparks the current was generally at 5 uA. About a minute after the 2nd, the current dropped to 4 uA.

70.75 kV. Short conditioning (response from all 3 monitors) period of about 10 seconds.

71 kV. 2 sparks one minute apart with some conditioning in between and after.

71.5 kV. Spark followed by 2 minutes of conditioning.

71.75 kV. One minute of conditioning.

Wednesday, December 16, 2020, 18:06

72.25 kV. Spark followed by a minute and a half of conditioning.

72.75. About a minute of conditioning.

73 kV. Instant spark followed by about a minute of conditioning.

73.25 kV. 30 seconds of conditioning then a spark. 1 minute of conditioning, then another spark, and conditioning done right after. Second one sounded like it activated the Faraday cup.

73.75 kV. Sporadic and weak conditioning? A few blips in voltage and current over about a minute and a half.

74 kV. Similar to previous but even less significant.

74.5 kV. Two minutes of conditioning.

Wednesday, December 16, 2020, 18:52

75 kV. 30 seconds of conditioning. Spark. 2.5 minutes of conditioning. 2nd spark. 10 seconds. 3rd spark; lowering voltage by 250 V for stability to capture footage of previous 3 sparks. Stable here for 5 minutes.

Wednesday, December 16, 2020, 19:01

75 kV. Nothing happening. Gonna leave for 30 minutes.

Wednesday, December 16, 2020, 19:31

75 kV for 30 minutes. No sparks or any other anomalies. Vacuum has been around 9.5e-7 Torr. Current hovering around 5 uA. Starting voltage ramp down.

Wednesday, December 16, 2020, 19:43

Ramped down. Nothing interesting. Turned power supply off in EPICS. Still on physically such that ramp up tomorrow can start remotely. Dumped data.

Ramping up to 75kV. Started drawing current at 63.5kV this time.

Now at 75kV, drawing 5uA of current. Ramp up easy.

Thursday, December 17, 2020, 13:02

Been at 75 kV since about 8:45. A single spark at 11:58.

Thursday, December 17, 2020, 18:10

75 kV. No sparks since that last one 6 hours ago. Current has been slowly decreasing over time, now sitting around 2 uA. Was about 5 uA around the time of the spark. Starting ramp down. Dumped data.

The 75kV power supply is now in EPICS under the usual TSG:BIAS controls. The upper limit has been set to 70kV to protect the transformer.

Thursday, February 08, 2018, 16:54

Testing the HV bias I found that the einzel lens was behaving strangely. When I tried to put it higher than 1kV, the current would start spiking from 12uA to > 100uA. The voltage would jump around quite a bit as well (+/- 100V). Everything seems the way it was before, except the EZL power supply is still connected in parallel with the old bias power supply, which is no longer powered. Maybe one of the transorbs connecting line and neutral on the bias side is fried? I will unhook the connection to the old PSU and try again.

Friday, February 09, 2018, 08:25    Disconnected the AC power chain from the old bias supply but now cannot turn on the new bias supply in EPICS because the "TSGBIASSAFETY ok" interlock is tripped. No idea what this means - maybe it checks for AC power?

Friday, February 09, 2018, 08:48    Reconnected power to old bias supply, does not fix problem. Talked to Mike, he thinks it is PLC related, so will call Gelo later.

Friday, February 09, 2018, 11:38 TSGBIASSAFETY ok interlock problem seems to have solved itself, it now appears to be working fine. Will turn off power for now and continue tests on Tuesday. (note: turns out Mike told Dave about the problem and he solved it. No one knows what this interlock is for, but it used to be reset using the Global Reset button and now the RST button for the power supply should also reset it.)

Ramped up to 60kV with the new power supply, same as what we did last time with the standard test stand bias supply (see entry #627 ). Much more instability on the bias current readout (see attached screen shot), develops around 54kV. As well, the old supply read out 37uA at 60kV while the new supply reads out ~85uA. This could just be an EPICS read back issue though.

Sparks at 62kV on the bias.

Turned it down, turned it back up and got a spark at 60kV.

Now up to 63kV, no sparks so far (5 mins). Left EE @ -3100V and EZL @ 28.5kV

There is the sound of a low level continuous discharge, like HV power lines, and a very strong ozone smell coming from the HV duct that sticks into the cage and carries the cables from the HV rack. Also seems to be present near the EE insulating standoff. Can't see anything though. Maybe just moisture in the air? Starts at 55kV on the bias, does not change with EE voltage.

Turned EZL up to 29kV, bias stable at 63kV for 11mins.

Sparks at 63.6kV in the EE spark gap, EE @ -3.1kV.

I vacuumed inside the HV cage, though it has many small areas that are difficult to access so I am not sure how great a job I did.

Turned the bias up and again at 55kV I hear small sparks near the end of the HV duct that brings the cables from the rack. Cannot see anything. If it is really sparking where it sounds like sparking, it must be from the edge of the duct to the faraday cage.

Changing the EZL voltage and the EE voltage has no effect on where it starts sparking.

Found TMSTP6 off, restarted it, seems fine now (drawing 0.8A)

The test stand holds up to 63kV, however at voltages over 54kV there are small discharges, rising to a continuous level around 60kV. The best guess right now is that these are coronal discharges coming from the end of the HV duct to the faraday cage. The only way to fix this would be to round out the edges of the duct, or to move the duct farther away. Since I have heard small discharges in other places, we may need to make a variety of modifications. Things that have had no effect:

1. Changing the EZL/EE voltages - break down is happening only between HV bias and ground

2. Cleaning the faraday cage

3. Locating sparks with a thermal camera

4. Conditioning - break down always happens at the same point

Tuesday, February 20, 2018, 09:01: Sparks at 62.5kV after a couple minutes. Sounds like they were in the EE spark gap but don't appear on the EE read current. Ozone smell around 61kV, so there are still some discharges.

Turned back up to 62.5kV but no sparks. Put it up to 63.5kV and there was a spark, but not in the EE spark gap as expected. Took down TP1B but everything is back up and seems fine.

1. Al corona shield installed over end of the HV duct to suppress discharges from the sharp edge of the duct.

2. Some moving and shortening of cables to keep them from running close to different voltages.

3. Changed the angle bracket on the 3M bias-EE resistor chain to a plate, same position.

4. Moved the 164K EE resistor chain to sit flat against feedthrough K.

5. Moved the bias-EE spark gap to sit flat against the back of feedthrough K, required tapping a hole in the back of the copper clamp.

6. Cap and top of rack vacuumed.

7. Piece of shielding removed from top of HV rack

Turning up bias, no corona discharge at 60kV but a spark at 61.5kV bias, 31kV EZL, -800V EE

Thursday, March 01, 2018, 10:26: BIAS / EZL / EE @ 65 / 32.5 / 3.2 kV

Thursday, March 01, 2018, 10:32: Spark* Knocked out turbo pump TMS : TP6 (Restarted) Communications restarted. RPM0A restarted.

Thursday, March 01, 2018, 10:44: BIAS / EZL / EE @ 61 / 30.5 / 3.1 kV

I have removed the resistor/varistor combinations that go between the poles of the target and tube heaters, and between those two supplies. I tested all the components to make sure they were still working after the sparks - for the record the varistors clamp at 23V, not 33V as implied by the schematic.

Tuesday, March 06, 2018, 10:48  BIAS/EE/EZL = 59.5/-1000/29.5  There was some kind of spark, the current on the bias supply went up to 400uA ( normally at 40 +/- 5 ) and the vacuum jumped a bit ( but still in the 10e-7 range ) but I didn't hear anything. It took out TP6 again. See first attachment.

Tuesday, March 06, 2018, 10:54  BIAS/EE/EZL = 60/-1/30

...

Problems

...

Tuesday, March 06, 2018, 12:00 BIAS/EE/EZL = 60/-1.5/29

Tuesday, March 06, 2018, 12:37 BIAS/EE/EZL = 62/-1.5/30

Tuesday, March 06, 2018, 14:11 BIAS/EE/EZL = 64/-1.5/31 No sparks but occasional ticking sounds from either the EZL or behind where the EE is... see second screenshot

Tuesday, March 06, 2018, 14:40 BIAS/EE/EZL = 65/-1.5/33

Test stand has been sitting at 65kV for about an hour now. Some small increases in bias power supply current but nothing significant (40uA). Some small sparks on the way to this voltage, and I ramped up very slowly. The corona discharges seen before seem to be related to the resistor/varistor combos since there are none now that I have removed them. Will redesign and reinstall.

The resistor/varistor combinations across the target + / -, tube + / - and target- / tube + have been remade and moved to the back of the power supplies to limit the corona discharges at higher voltages. Pictures attached.

First attachment: BIAS/EE/EZL = 63.25/-1.5/31 So far no issues.

Second attachment: BIAS/EE/EZL = 64.25/-1.5/32 Slight spark - bias current jumped from 40uA to 88uA and vacuum jumped from 2e-7 to 2e-6... Steerers went off.

Third attachment: BIAS/EE/EZL = 65/-1.5/32  Some small signs of instability in the bias power supply

Fourth attachment :  BIAS/EE/EZL = 65/-1.5/32  Been running for 20 mins now. More variation on the bias current output than at lower voltages but not too bad

Pressure:

Ramping up:

• Second attachment - bias at 50kV
• Third attachment - bias at 60kV
• Fourth attachment - bias at 65kV

Pressure has been slowly falling since we started this test - now down to 8.7e-7

Spark after 10 mins, see attachment 5. Very slight vacuum jump (8.5e-7 -> 1.2e-6) and bias current jump (36uA -> 113uA). Tripped TP6 and the steerers, as usual. Bias current read back more erratic afterwards (see sixth attachment).

System has been stable for 20mins, though current on bias is still more erratic than before the spark. Increasing He leak rate from 7 to 7.06 to bring vacuum back up to 2e-6 (see attachment 7). No effect from increased pressure.

Tuesday, March 13, 2018, 05:52: Power off.

Tuesday, March 13, 2018, 05:56: Waterlines purged

Tuesday, March 13, 2018, 05:57: Ion gauge, Turbos off.