Laura Lambert wrote:

Laura Lambert wrote:  Friday, February 03, 2017, 14:17 The endcaps are stacked together with a punched out disc of graphite foil placed in between each endcap for separation so endcaps won't fuse together. The end caps are further wrapped in a larger piece of graphite foil to hold together as a tube [same method used in elogID # 158 and 235] There are also 4 coated springs, 2 on each side of the endcaps tube, with the endcaps tube residing in the middle of the boat. The boat is wrapped with 3-layers of Ta heatshields. Chamber is currently being pumped down. Good vac at 3.0e-5, bad vac at 4.0e-5 Torr. OMEGA slope = 0.98  Monday, February 06, 2017, 09:29 Power outage this weekend and evap2 tripped off. Re-pumping down now...  Tuesday, February 07, 2017, 08:54 HS water valves opened, no leaks detected. IGP1 = 1.9e-7 Torr Tapped up manually to 35A Vacuum stable. IGP1 = 2.0e-7 Torr Initiating auto-ramp at 0.2A/min with a final setpoint of 450A. Final desired temperature = 1800C  Wednesday, February 08, 2017, 09:52 IGP1 = 2.98e-7 Torr TGHT = 325A, 3.5V Vacuum stable. Increasing ramping rate to 1.0A/min  Wednesday, February 08, 2017, 11:46 IGP1 = 6.3e-7 Torr TGHT = 433A, 4.89V Increasing max setpoint to TGHT = 500A OMEGA has still yet to show a temperature...should be reading points at this high in current Will go down to the lab and follow up on OMEGA settings to confirm everything is set up ok before proceeding to a higher current...  Wednesday, February 08, 2017, 16:03 IGP1 = 4e-7 Torr TGHT = 500A, 5.75V OMEGA still not reading Initiating auto-cool at -2A/min Will update elog with more details tomorrow  Thursday, February 09, 2017, 10:52 Evap2 was cooled down and opened up this morning. Turns out both legs on the target boat were touching the new heatshield and therefore had been loosing power. Normally a boat at 500A would read ~1800C, in this scenario at 500A the boat read ~1000C. A lot of power was being lost into the heatshield. See photos attached of target boat sitting at 500A. The heatshield is currently being ground down in those two spots to accommodate the target boat.    Tuesday, February 14, 2017, 15:43 Heatshield was ground back and target boat now fits nicely into heatshield without contact.

 Tuesday, February 14, 2017, 15:44

Boat with endcaps and springs reloaded today and pumped back down this afternoon.

HS water valves opened, no leaks detected.

Tapped up manually to 35A

Vacuum stable.

IGP1 = 3.5e-6 Torr

Initiating auto-ramp at 0.2A/min with a final setpoint of 400A.

Final desired temperature = 1800C

 Wednesday, February 15, 2017, 10:24

IGP1 = 7.2e-7 Torr

TGHT = 260A, 3.95V

OMEGA = 1158C

Vacuum stable.

Increasing ramping rate to 1.0A/min.

 Wednesday, February 15, 2017, 13:02

IGP1 = 2.0e-6 Torr

TGHT = 400A, 6.67V

OMEGA = 1530C

Increasing final setpoint to 450A

 Wednesday, February 15, 2017, 13:55

IGP1 = 2.5e-6 Torr

TGHT =450A, 7.7V

OMEGA = 1640C

Increasing final setpoint to 500A

 Wednesday, February 15, 2017, 15:13

IGP1 = 1.8e-6 Torr

TGHT = 500A, 8.59V

OMEGA = 1770C

MIKRON = 1740C

Tapping up manually to ~1800C...

 Thursday, February 16, 2017, 09:09

IGP1 = 5.28e-7 Torr

TGHT = 520A, 9.1V

OMEGA = 1821C

Target boat has remained at max setpoints for 17.5hrs.

Initiating auto-cool at 1A/min

 Thursday, February 16, 2017, 13:49

Increasing auto-cool to 2.0A/min

 Friday, February 17, 2017, 16:00

Vented in air and opened up today.

Endcaps looks good  see photos attached