Friday. July 26th 2019 

A new electrical configuration of the test stand was decided and installed. The TGHT and TBHT were parallelized in order to deliver up to 600 + 600 Amperes to the p2n target.

Connections:

TGHT+: D

TGHT-: C

TBHT+: one cable to E and one cable to G (both going down to the coil terminal blocks, which are connected to the target terminal blocks through a copper short.

TBHT-: both cables to F. One 4/0 cable was run from F to H to achieve the same configuration as for TBHT+. The H terminal is connected to I (HV ground, conencted to the target copper heat shield) through a braided cable

One braided cable was connected from C to H so the target line should have the same potential as the TBHT/coil lines.

Saturday, July 27th

The current was ramped from the TBHT and TGHT in parallel up to 400+400=800A.

Sunday, July 28th

One leg of the target is glowing a bit, while the other doesn't. This suggests the current path is not straightforward as we planned.

Temperature measurements of the cables on top of the test stand were performed using a mini IR thermometer (FLUKE, borrowed from Arthur).

Temperature of the braided cable from C to H = ~50 °C --> This points to an imbalance of current between the two lines (TGHT and COIL lines). This might be alright.

Temperature of the braided cable from H to I = ~130 °C. This likely points to a short circuit between the target and the copper heat shield.

Monday, July 29th

In order to understand if the target is broken or touching the heat shield, we opened up the service cap.

- The braided cable from H to I was removed

- The braided cable from H to Q was disconnected

These two modifications were made so that the current cannot come back from the heat shield, but has to go through the target lines.

The 4/0 cables from the PS to the feedthroughs were removed so that we could confirm there is a short between C (target) and I(HV ground/heat shield). The 4/0 were than put back on the feedthrough connections.

Under advice of Dan Louie and Arthur, we did not change any configuration of the power supplies. We know that the current would go through the controls loop, but the impedance of this electronics should be high enough to sustain the current load.

At 3pm, the ramping was still increasing the current on the target, but one leg (the right one) was still glowing. By this time, the total current in the target assembly is ~500 amperes, so there should be no signs of any glowing happening. Probably there's something wrong with the target itself. We're opening up to check the status of the target.

Tuesday, July 30, 2019, 10:00: Venting. 

Tuesday, July 30, 2019, 10:03: Purging heat shield water loop. 

Tuesday, July 30, 2019, 11:46: P2N removed