Friday, June 14, 2019, 17:10
A 14 mm die was used to cut out discs from strips
The target consists of 236 discs of 10 cm in length - all single discs, no packs.
231 x UO2/C discs = 25.76 g
12 UO2 discs for measurements = 1.49 g
Graphite insert without caps= 11.59 g
The loaded insert is placed on target boat.
Boat previously coated with TaC and sintered.
Ta-target boat is wrapped with 3-layers (2 new one used) of heat shield and installed in evap1.
Chamber is pumping down.
Monday, June 17, 2019, 08:56
Pressure limits:
Good vacuum 1e-1 Torr
Bad vacuum 5e-1 Torr
IGP1 = 6.600777e-7 Torr
Current tapped manually to 80 A at 1A/s in 10 A blocks with a waiting period of 20 s between each increment.
Initial IGP1 = 5.31 e-6 Torr
Monday, June 17, 2019, 10:03
After 42 minutes the pressure started dropping and the current rate was changed to 1A/s with for 20 second intervals followed by 20 second wait while monitoring pressure.
Monday, June 17, 2019, 14:41
Current was tapped to 100A but the pressure increased too rapidly; therefore, the current was tapped down to 75A.
After pressure stabilized, the current was tapped up to 100 A @1A/s in 20A segments and 20 second pauses.
Continued tapping up at the above rate until 160A, at which point the pressure shot up and tripped the system.
The pressure stabilized within 18 minutes.
The wait interval on the heater ramps control was changed to 1s
The current increment was set to 0.2A with a final value of 200A
At 170A the autoramp was stopped and the current manually tapped down to 160A to prevent rapid pressure buildup.
5 minutes later the pressure had stabilized and autramp was restarted.
At 160A we changed the waiting interval to 10s and the current increment to 2A.
At 200A we stopped autoramp and manually tapped at 1A/s in 20A segments with 10s pauses.
At 360A, we changed the current increment to 1A while keeping the wait interval at 10s.
At 440A the autoramp was stopped to change the current increment to 0.5A while the waiting interval was kept at 10s.
The autoramp final current was set to 500A.
At 495A the autoramp was stopped because the pressure was dropping significantly.
The Target was left for 3 hours at 495A.
Pre-cooling conditions:
TGHT = 494A, 4.8V
IGP1 = 6.7e-6 Torr
Cooling rate = -2A/min
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