 Wednesday, February 07, 2018, 08:46, Aaron Schmidt, , , , , , , , BIAS Power supply installation 
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Wednesday, February 07, 2018, 08:40: A 75 kV Glassman power supply was installed in the rack for use in further HV testing.
-The 75kV power supply is linked into the keyed interlock system. The key & switch labelled BIAS/EZL will unlock it.
-The PS is currently not connected to the epics controls and can only be adjusted manually. |
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Thursday, February 08, 2018, 14:44, Carla Babcock, , , , , , , Done, Conditioning station power supply integrated into EPICS
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| 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. |
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Thursday, February 08, 2018, 16:54, Carla Babcock, , , , , , , , EZL strange behaviour
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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 |
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Friday, February 09, 2018, 08:57, Carla Babcock, , , , , , , , TSGBIASSAFETY ok interlock
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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 |
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Tuesday, February 13, 2018, 12:17, Carla Babcock, , , , , , , , Ramping up bias to 60kV with conditioning station supply
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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. |
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Tuesday, February 13, 2018, 16:47, Carla Babcock, , , , , , , , Ramping to 63kV - some sparks
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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 |
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Friday, February 16, 2018, 15:21, Carla Babcock, , , , , , , , Cleaned HV cage - trying bias again
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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. |
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Monday, February 19, 2018, 08:30, Carla Babcock, , , , , , , , TMSTP6 off
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| Found TMSTP6 off, restarted it, seems fine now (drawing 0.8A) |
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Monday, February 19, 2018, 14:01, Carla Babcock, , , , , , , , Attempts to get to higher voltages, summarized.
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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 |
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Tuesday, February 20, 2018, 09:04, Carla Babcock, , , , , , , , Trying HV with rubber corona shield
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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.
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Friday, February 23, 2018, 08:50, Aaron Schmidt, , , , , , , , New Al Corona
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| Friday, February 23, 2018, 08:50 |
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Monday, February 26, 2018, 09:13, Carla Babcock, , , , , , , , Running list of changes to the ISAC test stand for >60kV operation 6x
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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. |
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Wednesday, February 28, 2018, 11:50, Aaron Schmidt, , , , , , , , HV Test Np
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New parts installed. Corona Shield, brackets, and board/spark gap orientation.
Wednesday, February 28, 2018, 11:48: Power on. Ready to test
Wednesday, February 28, 2018, 14:00: BIAS / EZL / EE @ 30 / 13 / 1.5 kV |
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Thursday, March 01, 2018, 10:05, Carla Babcock, , , , , , , , HV tests with corona discharge problems solved
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Turning up bias, no corona discharge at 60kV but a spark at 61.5kV bias, 31kV EZL, -800V EE
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Tuesday, March 06, 2018, 10:55, Carla Babcock, , , , , , , , Trying HV without electronics
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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 |
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Thursday, March 08, 2018, 17:47, Carla Babcock, , , , , , , , Change of electronics on target and tube power supplies
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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. |
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Friday, March 09, 2018, 08:57, Carla Babcock, , , , , , , , HV test with electronics moved to rack
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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. |
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Monday, March 12, 2018, 10:07, Aaron Schmidt, , , , , , , , HV Test w-gas
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Monday, March 12, 2018, 09:45: Gas lines opened. Leak rate set. Vacuum @ 1.16e-06T
Monday, March 12, 2018, 10:00: RGA on
Monday, March 12, 2018, 10:07: RGA off. Manually shut off power as well |
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Monday, March 12, 2018, 10:44, Carla Babcock, , , , , , , , Bringing up HV with gas on 8x
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Pressure:
Previous HV tests done at 2e-7 pressure.
Current pressure 1.1e-6 (see previous entry for RGA stats) - first attachment shows source
gas setup. Argon, neon and He leaks all on.
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Tuesday, March 13, 2018, 06:00, Aaron Schmidt, UC#22, LP-SIS, ITE, TM4, , , In progress, Conditioning Heat Shield for UC#22
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Tuesday, March 13, 2018, 08:50: Roughing.
Tuesday, March 13, 2018, 09:10: Turbo Pumps started.
Tuesday, March 13, 2018, 09:15: Ion gauge on. |
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