The assembly consists of two tantalum foils, 0.001" thick, which are radially crimped to form a cylindrical surface. The outside support are two P2N conditioning legs, and the inside supports are tantalum tapered rings. The solidworks geometry for this test is ITD0811 in PDM.
The P2N is attached to EVAP1 with copper legs and copper shims. A current ramp up to 600 A on the target wrapped with heat shields is attempted to benchmark the current/voltage increase in a bare target, so that we have reference values for future rampings with graphite and target material inside.
The heat shields consist on two layers of Ta sheets on the body of the P2N secured with Ta-wire and two layers of Ta sheets on one side of the P2N.
Tuesday, January 28, 2020, 10:11
A P2N container with heat shields, and without graphite container was installed in the EVAP1
Chamber is currently being evacuated.
Wednesday, January 29, 2020, 10:12
Pressure IGP1=1.87e-6 Torr
Final desired current TGHT = 600 A
Manually tapped to 40 A.
Voltage increased accordingly in an stable way.
Wednesday, January 29, 2020, 10:33
Autoramp is set to 3/30s to 300 A
The voltage and vacuum were stable so the autoramp was kept at 4/30s and the final current was set to 600 A
Accidentally went up to 600 A (1.98 V)!
When updating autoramp to 600 A, did not realize that procedure status was Active.
NOTE: If the procedure status is "active" the heater autoramp, does not "ramp" the current input in "final value", it will go in one step to that current.
The current was manually ramp down to 300 A
TGHT=299.52A, 0.89 V
Wednesday, January 29, 2020, 13:25
After approximately 2 hours conditions IGP1=1.6e-6Torr, TGHT =300 A, 1V.
The current ramp was started again: 4A/30s to final value of 600 A
Wednesday, January 29, 2020, 14:07
After 15 min, TGHT=599.424A, and 1.983 V (unstable) (see figure "P2N-test2_final voltage")
The current was ramp down to 0 A at -5A/20s
EVAP1 was vented with aair and the container was removed,
the copper shims and legs did not present signs of damage
the body's tantalum sheet had wrinkles inside,
the tantalum foils unfasten a bit, but were adjusted. |