Darwin Ortiz Rosales wrote:

Tuesday, November 26, 2019, 14:53 Total number of foils: 504 Total length packed 17.4 cm container has 3 Ta heat shields. No endcaps inserted to facilitate out-gassing Two TaC coated Ta wire springs inserted at either end. Initially to ramp TGHT and TBHT to 50A at 1A/min Then heat manually to OMEGA ~1400 C , ramping TGHT manually and automatically  to reach 530A A (Omega slope set = 0.990) Then temperature= 1900 C (Correction = 1800 C, NOT 1900 - JW), Omega Slope set = 0.990 (use 1.08, check temp, JW), manually and automatically ramp to 700A (check temp to see if it's matching with the 1.08 slope), TGHT will be tapped up accordingly to reach desired Temp. TBHT will be set fixed at 230 A (max).  TBHT heated manually and automatically to max. Good vac at 3.00 e -5 Torr Bad vac at 5.00 e-5 Torr System experienced some vacuum issues due to cooling water leak in a heatshield line.  Evaluation discs not included because no space. Total Green disc mass measured = 58.250 g   Tuesday, November 26, 2019, 15:00 IGP1= 7.4e-06 Torr.  No leak issues found after last fix (Anders will add details). Tuesday, November 26, 2019, 15:33 TGHT= 52.7A, .22V   TBHT= 49.3A, .52V IGP1= 7.202 e-06 Torr (trending up so will allow to stabilize).

 Wednesday, November 27, 2019, 17:44

I'll take over from here to step up the target heater, and I'll coordinate it with Darwin. 

 Wednesday, November 27, 2019, 20:36

Note: Sintering temp should be at 1800 C, NOT 1900.  Use Omega slope 1.08 and check temperature.  Correction made on elog #471.

Continue to step up TGHT and TBHT, keeping vacuum below 1.5 e-5 Torr. 

 Thursday, November 28, 2019, 03:06

TGHT reached to 400A/5.29V, TBHT at 230A/3.13V. 

Vacuum coming down from 1.3 e-5 Torr.

OMEGA = 1105 C (slope at 0.99).

Instructions for Darwin:

1.  Confirm temperature - check the temp plot from the TaC coating step. 

2.  Change OMEGA slop to 1.08 - check to see if this matches the temp plot.  If not, bring it back to 0.99.

3.  Continue to step up TGHT, check temp at 1400C (change slop 1.08 and check), 1500 C, 1600 C (check windows for coating - if any coating, then OMEGA is no longer useful hereon)

4.  Use the temp plot and continue to tap up TGHT to reach 1800 C and hold it for at least 4 hours or until the vacuum goes below 1 e-6 Torr then proceed with cooling down.

5.  Use the auto cooling program for TGHT (-2A/min) and TBHT (-1A/min)

Note:  For ramping up TGHT, keep vacuum below 1.5 e-4 Torr and keep tapping up to reach 1800 C.  Above 1100 C, this should be a quick step to get to 1800 C; should take < 2 hrs to get there.  

See the striptool or the attachment below to see how I did it. 

Once the chamber is cool down, take out a few samples for SEM analysis. 

Good luck!