John Wong wrote:

Laura Lambert wrote: John Wong wrote: Laura Lambert wrote:  Monday, June 29, 2015, 16:17 Target container is coated with TaC. No Ta-heat shields are used. TGHT will be ramped up to 580A at 0.2A/min. TBHT will be ramped up to 230A at 01A/min. Chamber is currently being pumped down.    Monday, June 29, 2015, 23:37 Opened the HS valves around 5pm.  Small leaks or just a vibration in the pipe line caused a rise in vacuum.  Leak rate is small, so allow the chamber to continue to pump down over night. Sintering process can begin tomorrow if vacuum is allowed.    Tuesday, June 30, 2015, 08:22 IGP1 = 3.6e-7 Torr. Tapped up manually to 40A. Vacuum looks good. IGP1 = 6.9e-7 Torr. Inititating auto-ramp...  Thursday, July 02, 2015, 09:56 IGP1 = 8.9e-7 Torr. OMEGA = 1728C TGHT and TBHT = 580A and 230A respectively. Tapping up manually to 1800C.  Thursday, July 02, 2015, 11:02 TGHT = 615A, 10.9V OMEGA = 1800C IGP1 = 1.1e-6 Torr. Will continue to heat for 4hrs.  Thursday, July 02, 2015, 15:43 Target container remained at 1800C for 4hrs50min. Initiating auto-cool for TGHT = 2A/min and TBHT = 1A/min.  Friday, July 03, 2015, 08:24 Vented in air and opened up this morning. Edge of container on both ends not fully sintered [see photos]    Monday, July 06, 2015, 11:54 Inner tube surface isn't homogeneously sintered with TaC (see attachment).   A second coating may help.   For the re-sintering process, the target container will be wrapped with 6.2cm Ta (width) foil as a layer for heat shield on each side of the tube,  excluding the centre block - just like the same process was done last time, see e-log ID#217.   The Ta-foil and the target tube will be spaced with Ta wire coiled around it.   TGHT can be ramped up about 520A/9.1V to achieve 1900C.  Heating time for 3-4 hours until vacuum comes down to low 10-6 Torr.

 Monday, July 06, 2015, 16:28

Container has been re-coated with TaC.

Target container is wrapped with a single 15.5cm x 8.5cm Ta foil heat shield on each side of the center block, spaced with Ta wire coil.

Chamber is currently being pumped down.

 Tuesday, July 07, 2015, 09:36

HS water valves were opened this morning, no leaks detected.

IGP1 = 6e-7 Torr.

Tapped up manually to 30A.

Waited ~1hr.

Vacuum stable, IGP1 = 1.9e-6 Torr.

Initiating auto-ramp at 0.2A/min and 0.1A/min for TGHT and TBHT respectively.

 Target container reached max setpoints of 520A/230A and 1950C ~6hrs ago.

IGP1 = 7.6e-7 Torr.

Initiating auto-cool at 2.0A/min and 1.0A/min for the TGHT and TBHT respectively.

 Friday, July 10, 2015, 11:16

Vented in air and removed from evap2.

Again, edges not fully sintered [see photos]

Inside of container looks better, fully coated.