Thursday, February 10, 2021, 12:00

Objective: Heat a Re wire to evaporate it and deposit a layer of Re on the inner surface of a Ta tube.

A Re wire of 1mm diameter was clamped with Cu brackets in EVAP2, the wire is partially enclosed in a Ta tube. EVAP2 pumping down 

The wire needs to be heated to 2500 degC since this is its sublimation temperature at 8e-7 Torr

There is not a reliable system to measure the temperature of the wire but the readings of the micron, manual, and omega pyrometers will be register.

According to COMSOL simulations a power and taking in consideration the EVAP2's power loss, a power of 520 W (5A, 10V) is required.

Thursday, February 11, 2021, 15:39

Pressure 3.78e-7 Torr, current rate set to 10 A @ 0.5 A/min

Thursday, February 11, 2021, 16:32

Pressure: 4.01e-7 Torr, TGHT = 10A, 1.719 V. The voltage has stabilized, the wire is glowing but not enough for reading with micron nor omega, manual reads 970 degC. Also, the wire formed an arc (crest).

Thursday, February 11, 2021, 16:44

 Pressure 3.8e-7 Torr, TGHT  = 10 A, 1.723 V ramp set to 20A @ 0.2 A/min

Thursday, February 11, 2021, 17:26  

Pressure increasing 4.7e-7 torr, TGHT = 20 A, 4.016 V, the wire does not seem to be changing, 

Thursday, February 11, 2021, 18:02

Ramp set to 30A @0.4A/min

Pressure  7.2e-7 Torr, TGHT = 30A, 6.561V, manual pyrometer reads 1720degC

Ramp set to 40A @0.4A/min

Thursday, February 11, 2021, 18:35

 Pressure 2.1e-6Torr and increasing, TGHT = 40A, 9.1V, manual pyrometer reads ~1880 degC

Ramp set to 50A @ 0.4 A/min