Laura Lambert wrote:

John Wong wrote: Laura Lambert wrote:  Tuesday, June 30, 2015, 13:28 Target container was previously coated with TaC spray and sintered. It's is wrapped with 3 layers of Ta-heat shield, including the center block. The target consists of 221 discs of UCx with 7.5cm in length. A regular TaC coated endcap is inserted left, wrt the ionizer tube pointing down, so the right is open - discs are held on with Ta wire spring. The chamber is currently pumping down. TGHT will be ramped up to 520A at 0.1A/min Parameter setup: 5.0e-5 good vac, 6.0e-5 bad vac.  Tuesday, June 30, 2015, 14:43 IG1 = 1.8e-5 Torr. Tapped up manually to 30A. Vacuum stable; IG1 = 1.2e-5 Torr. Initiating auto-ramp.  Thursday, July 02, 2015, 08:41 EVAP1 was tripped off due to backflow preventer test this morning. IG1 - 4.2e-6 Torr. Tapping back-up manually before re-initiating auto-ramp.  Thursday, July 02, 2015, 11:49 Tapped up manually to 85A, 0.65V IG1 = 3.6e-6 Torr. Initiating auto-ramp.    Thursday, July 02, 2015, 12:58 NOTE:  Before venting the EVAP1 chamber, the Ar line must disconnect from Peter's sampling chamber (inside the fumehood) and connect back to the EVAP.     Friday, July 03, 2015, 13:42 water valve tripped off at ~1pm, which subsequently tripped off the TGHT [see photo] currently trying to figure out what caused this to occur before re-starting....  Friday, July 03, 2015, 14:47 All water valves look good, flow is good. WV turned back on, TGHT turned back on.  Tapped back up manually to 20A. IG1 = 2.3e-6 Torr Initiating auto-ramp at 0.1A/min with a max setpoint of 150A over the weekend. Will continue to ramp up monday.   Approved by Peter Kunz.  Monday, July 06, 2015, 09:29 TGHT reached 150A 1.5hrs ago. Vacuum stable. IG1 = 2.7e-5 Torr. Re-starting auto-ramp at 0.1A/min with a max setpoint of 520A.

 Wednesday, July 08, 2015, 10:44

The carbonization process is complete; chamber vacuum is stabilizing at 9.5e-6 Torr. 

Currently TGHT is at 430A.  Increased TGHT ramping rate to 1A/min.  Target should be at max current (520A) in 1.5 hours, so TGHT can be ramped down around 4:30pm today. 

 Wednesday, July 08, 2015, 16:36

TGHT at 520A/5.884V for over 4 hours.  Pressure coming down, currently at 1.42e-5 Torr. 

Initiated cooling at -2A/min. 

Chamber can be vented in Ar tomorrow and the target will be inspected.

Thursday, July 09, 2015, 17:08  

The target was taken out from the evaporator and inspected. 

Some "burnt" marks on the ionization legs can be observed and also the centre support leg is bent.  (see photos#1)

Not sure if the centre leg came in bent after machining or it happened during the carbonization process??  Do not have photos of the container before the process to compare.  

A few things to note…  During the process, the power supply did tripped off twice due to the cooling water valve shut off. (see photo#2).  An assumption is that sudden cool down of the hot target might have caused the quenching effect. 

No other visible damage.  

End caps are inserted and ready for assembly.

Link to photos:  https://www.dropbox.com/sh/c1ake0fu4x7lckc/AAD0F8TVRrpCbbHquEvSkyYIa?dl=0