| Laura Lambert wrote: |
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| John Wong wrote: |
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| Laura Lambert wrote: |
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Friday, June 20, 2014, 11:14
Total number of foils: 515 discs
Total mass of materials [incl graphite foils]: 64.7224g
Total length packed: 17.8cm
Container is wrapped with 3x Ta-heat shields.
Currently being pumped down.
Friday, June 20, 2014, 14:56
HS cooling water valves opened, no leaks detected.
IGP1 = 6.2e-6 Torr
TGHT max = 820A/ 17V
TBHT max = 300A/ 5V
Stepping up manually to 40A
Friday, June 20, 2014, 16:04
IGP1 = 8e-6 Torr
Slowly stepped up to 35A manually.
Vacuum has stabilized.
Initiating auto-ramp at 0.1A/min
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Friday, June 20, 2014, 16:16
Changing the heating current...
From the previous SiC targets, TGHT was ramped up to 800A and yellow crystals were found; the end caps and target legs were also found broken (see my iPad). This might be too hot for the Ta-boat to handle the sintering process.
For this process,
TGHT will ramp up to 600A and TBHT to 230A over the weekend.
Then, the temperature will be measured. The sintering temperature of SiC is ~1800 - 2000C.
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Monday, June 23, 2014, 09:45
IGP1 = 5e-6 Torr
TGHT and TBHT are at ~200A
Increasing ramping rate to 0.2A/min
Monday, June 23, 2014, 11:19
IGP1 = 6.9e-6 Torr
Increasing ramping rate to 2.0A/min
Monday, June 23, 2014, 12:09
JW: Pressure went up too fast... lower the TGHT ramping up rate to 1A/min.
Tuesday, June 24, 2014, 16:06
Increasing current with respect to temperature: See attached table
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Tuesday, June 24, 2014, 23:44
Target has been heated at 600A. Local temperature measured on the right leg = 1814C.
RGA/ striptool/temperature data can be found on this link:
https://www.dropbox.com/sh/69memvh6fthodoz/AABZiSKAR9njhbqO4sBATVbla
Something interesting was observed about the out gassing of this target - the right window was coated when the temperature rose above 1500C (on the right end, could be hotter inside?) - see attachment.
I suspect this is Si vapour deposited on the window when the target heater got closed to the sintering temperature for SiC (1800 - 2000C).
Once the chamber is vented, the coated window will be inspected and analyzed. More details later...
Initiate auto-cooling (slow cool down) TGHT 1A/min; TBHT 0.5/min. Chamber should be able for venting tomorrow afternoon.
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