Thursday, December 05, 2024, 14:05 Pressurized ATTS with argon, swapped out samples, and repressurized and heated chamber.

  Friday, December 06, 2024, 16:03 Heated and cooled a sample in the ATTS 3x

  Tuesday, December 10, 2024, 14:38 Depressurized ATTS using argon, switched out samples, and repressurized ATTS. Heated new sample to 1000 degrees Celsius.

 Note, ground and HVC (high voltage common) are used interchangeably here.

Monday, December 16, 2024,   in the previous test, elog 1038, it was found that the cathode was unable to hold any voltage and was shorted to HVC. The cathode was shorted directly to ground, with the cathode supply current limiting upon being powered, unable to reach even 1V.

After testing, the ANODE power supply stopped functioning and was unable to provide and voltage or current.

When the target was removed, it was found that the TBHT terminal was just ~100Ω from HVC. When I shorted the TGHT to TBHT terminal, as they are when the target is installed, the resistance from TBHT to HVC dropped to just 1Ω. Prior to the anode power supply stopping, it was found that when it was powered on with no target present, it was able to hold voltage, but still drew significant current: up to 400mA when provided less that 20V. This should be completely open, losing no current at all.

Keiko and the controls team have been looped in to address the issue with the ANODE power supply as it may be a controls issue. They believe there are a few possibilities for its error that must be investigated prior to deferring to the power supplies group. This will continue to be investigated

    ********** UPDATE: ISSUE RESOLVED ********* There is simply a physically triggered interlock that requires the faraday cage door to be closed to operate the ANODE power supply

When investigating the resistive short from the TBHT, I first noted the resistances between each of the channels: TGHT(-) to TGHT(+) 30↨Ω; TBHT(-) to TBHT(+) 20Ω; TBHT(-) to TGHT(-) 100Ω; TBHT(+) to TGHT(+) 140Ω. I also reconfirmed and noted relevant connections at the feedthroughs: There are NO visible shorts to HVC from the TGHT or TBHT feedthroughs. From TGHT(-), there is one 50kΩ resistor with varistor, between TGHT(-) and TGHT(+) there is a100Ω with varistor. I then removed the back of the faraday cage to investigate possible paths to ground from the TGHT and/or TBHT. This showed that TGHT- was grounded through a varistor (checked, functioning correctly, OL at low voltage), TGHT- to + has varistor||100Ω, TBHT- to + has varistor||100Ω, and TBHT- to TGHT- has varistor||100Ω. These fit in accordance with the observed resistances between the terminals.  

I also disconnected the ANODE power supply from its output wire to further investigate without possible issues from the power supply. At this point, (after I had remade the varistor connections) I began to observe that the TGHT and TBHT terminals were all detached from ground by 50kΩ (expected amount, given that there is a 100k||100k resistor from TBHT- feedthrough to ground). When I reattached the anode power supply, that value dropped to 35kΩ, I assume due to internal resistance of the power supply. I placed everything back in position and (repeatedly) ensured that the 35kΩ separation persisted. It seems that this shorting issue has resolved itself. It may be that the was an accidental connection made from an unshielded wire inside the faraday cage.

Friday, December 20, 2024, 09:37    turned off all 4 turbopumps. winding down prior to evacuating.

Friday, December 20, 2024, 11:43 Purged and closed all water cooling lines.

Friday, December 20, 2024, 15:54   removed target and installed Uline.

 roughing down test stand 

Friday, December 20, 2024, 16:17    valves closed and roughing pump off. 

Friday, December 20, 2024, 16:17   shut down test stand computer for holiday break 

Recent tests have shown that CATHODE voltage breaks down at ~130V, continually leaking current and progressively dropping voltage, making febiad CATHODE testing impossible.

Thursday, January 23, 2025, 15:18    disconnected cathode wire from TBHT feed through, simply suspended in cage.

voltages are held for ~1min prior to increase. current will be reported after 1min and stable.

100V - 0.000mA

120V - 0.000mA

130V - 0.000mA

140V - 0.000mA

150V - 0.000mA

170V - 0.000mA

200V - 0.000mA

- the Cathode wire and power supply have no leak problem

Thursday, January 23, 2025, 15:42

Reattached the CATHODE line to TBHT feedthrough. Removed the 100||100kΩ resistor pair that connects TBHT to HVC.

Same process as before:

100V - 0.000mA

120V - 0.000mA

125V - 0.000mA

130V - 0.000mA

135V - 0.000mA

140V - current limit ---> dropped to 52V

-- The TBHT resistor pair is not the problem

venting chamber to investigate lines.

Thursday, January 23, 2025, 17:05

removed piece of broken ceramic that held the coil terminal

still current leaking, but it's not as immediate or as shorted. more resistive.

__V__mA__

30    0

35    2.4

40    6.1 

45   12.2

50   19.5

55   32

60   gradually ramped up to limited

Thursday, January 23, 2025, 17:10

Disconnected COIL terminal.  Behaviour still similarly bad. Doesn't seem to have improved.

Disconnected all TBHT and TGHT feedthroughs. ALL are now isolated from ground (AS BEFORE). TBHT + and - are isolated from all others, TGHT + and - are isolated from all others but 100R apart due to resistor at feedthroughs (as expected).

Increasing CATHODE voltage on TBHT+ feedthrough to test isolation.

V ____ mA

120  ___ 0

135 ____ 0

150 ____ 0

200 ____ 0

- The TBHT+ terminal does not leak directly to ground

Connecting CATHODE cable to TBHT(-) feedthrough to test

V___mA

130 __ 0

150 __ 0

200 __ 0

- the TBHT- terminal does not leak directly to ground.

Connecting CATHODE to TGHT+ feedthrough , and disconnected the 100R between - and +

V ___ mA

100 __ 0

150 __ 0

200 __ 0

- the TGHT + terminal does not leak directly to ground

Connecting CATHODE to TGHT-  feedthrough:

V __ mA

125 __ 0

150 __ 0

200 __ 0

- the TGHT- terminal does not leak directly to ground.

connected cathode cable to TBHT+ cable.

V __ mA

30 __ 0

40 __ 0

50 __ 12

60 __ 35

70  -> 60__ 80 current limited

Disconnected 100R path between TBHT and TGHT power supply

CATHODE cable still on TBHT+ cable

V __ mA

150 __ 0

200 __ 0

TBHT is not the problem

reconnected 100 path from TBHT to TGHT.  REMOVED varistors that connect TGHT to ground

V __ mA

100 __ 0

200 __ 0

These are likely the issue.

Reconnected varistors to confirm

SHORTED at 50 V -- 10mA, 65V gives 80mA, current limited.

Removed varistors.  WIll have to acquire appropriately specced ones