Wednesday, July 17, 2019, 10:57

Annealing of five RRR Nb samples following cold-working and resistance measurements.  Used to validate computational annealing model developed for SRF studies.  For more information contact Norman Muller, x6398.

Desired temperature 1025 C.

Five Nb samples wrapped with Nb foil were set on a tantalum boat (coated with TaC)

the tantalum boat was wrapped with two tantalum sheets.

The boat was installed in the EVAP2.

The initial vacuum was IGP1 = 1.26e-6 Torr.

Ramping rate 5 A/min to final current of 200 A.

Wednesday, July 17, 2019, 11:18 

At 155 A, the ramping rate was changed to 1 A/min 

Wednesday, July 17, 2019, 11:28 

The ramping was stopped at 167 A.

 Wednesday, July 17, 2019, 11:57

Conditions:

IGP1 = 1.65e-6 Torr

TGHT = 2.54 V, 174.46 A

Temperature ~ 950 C

Wednesday, July 17, 2019, 18:07

IGP1 = 1.16 e-6

TGHT = 3.18 V, 206.7 A

Temperature ~950 C

Cooling ramp 10 A/min 

 Vented with air

Suggestion for future annealing:

  Use tantalum boat without TaC coating.