The electrical feedthroughs at the top of the test stand module were reconfigured to deliver up to 1200A to the p2n target.

1) The two COIL lines (one + and one -) were disconnected from their terminals E and F

2) The TBHT terminals (two + and two -) were disconnected from A and B

3) The two TBHT positive terminals are connected to E and G respectively. The two TBHT negative terminals are both connected to F, and a 4/0 cable is run from F to H

4) The three TGHT + terminals are left connected to D. The three TGHT - terminals are left connected to C

In the vacuum chamber, COIL and TGHT terminals of the same polarity are shorted by means of thick copper bars specifically machined to match the test stand terminals geometry. The test can proceed by ramping both TGHT and TBHT up to 600 A each, possible at the same time and speed.

The wiring diagram is shown in the attached picture 

Extech measurements before heating (µOhm):

TGHT Left leg Ta-Cu: 205, 215, 212, 201.

TGHT Right leg Ta-Cu: 287, 295, 275, 292.

TGHT Ta legs: 596, 606, 597, 598.

TBHT A: 1470, 1471.

TBHT B: 1469, 1469.

Wednesday, July 22, 2020, 16:21

Rampup finished around 2PM, looks good. Around 300+300A the TBHT voltage limit prevented the TBHT current to increase, and instead it decreased. Aaron ramped it down, adjusted the voltage limit and proceeded without issues.

The water flow and temperatures looked fine.

Attached the plots and a picture at 1200A

 Thursday, July 23, 2020, 11:53

Frank Song checked for us the status of the test stand. Pictures looked good, despite the reflections, I can't see sign of the flexy legs glowing. Thank you Frank!

The voltage on the TGHT has dropped 0.02 V, and the voltage on the TBHT (COIL lines) has dropped by 0.04V in 20 hours. I think it's negligible, just a sign of some sintering.

The cooling parameters are as follows:

Input 1: 28.05 C

Input 2: 8.49 lpm

Input 3: 27.79 C

Input 4: 11.14 lpm

Input 5: 27.72 C

Input 6: 3.90 lpm

Input 7: 27.78 C

Input 8: 7.79 lpm

Friday, July 24, 2020, 16:42

This morning I saw the target for my first time and not in a picture. I could see a mild glow in the center of both flexy legs, while the external foils seemed cold. This seems really good, as expected!

Water parameters were checked:

Input 1: 27.75 C

Input 2: 8.38 lpm

Input 3: 27.52 C

Input 4: 11.13 lpm

Input 5: 27.37 C

Input 6: 3.93 lpm

Input 7: 27.53 C

Input 8: 7.78 lpm 

Monday, July 27, 2020, 09:35

Aaron's measurement from today at 7:30am

 Input 1: 26.61 C

Input 2:  8.25 lpm

Input 3: 26.35 C

Input 4: 11.19 lpm

Input 5: 26.21 C

Input 6: 3.84 lpm

Input 7: 26.35 C

Input 8: 7.76 lpm

FM

Thursday, July 30, 2020, 15:53: Auto-cooling TGHT/TBHT to 0 @ 4 A/min 

Thursday, July 30, 2020, 23:02

Ramp down terminated around 7pm, the current was ramped smoothly but the voltage from both PS (TGHT and TBHT) had some bumps in correspondance with vacuum response. Maybe something was shorting? A thorough inspection of the heat shield and target might tell more.

Thanks Fernando for ramping down! 

Tuesday, August 04, 2020, 07:33: PS / sources off. Lock out. IG & Turbo pumps off. Purge waterlines. - AS

Tuesday, August 04, 2020, 09:32

Started rewiring the test stand.

TBHT+ (A1 and A2): connected to A

TBHT- (B1 and B2): connected to B

COIL+ (A3): connected to E

COIL-(B3): connected to F

4/0 short connection from F to H removed

Tuesday, August 04, 2020, 15:27

Extech measurements after heating (µOhm):

TGHT Left leg Ta-Cu: 160, 176, 184, 180

TGHT Right leg Ta-Cu: 49, 48, 52, 53.

TGHT Ta legs: 470, 469, 463, 480.

TBHT A: 2400, 2229,2492.

TBHT B: 2361, 2411, 2412.