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Message ID: 20     Entry time: Wednesday, May 11, 2011, 16:23
Author: John Wong 
Target Material: SiC 
Target Oven W.O#: 38481-8 
Source: HP-FEBIAD 
Status: Problems 
Subject: Organics burnoff & Sintering  

Wed May 11 16:20:21 2011:  The HP-FEBIAD (w.o#38481-8) was filled with SiC (8.5mm, 555 discs).  The target is wrapped with 3 Ta-heat shields and is in the evaporator, which is being pumped down. 

Thu May 12 10:52:48 2011:  The evaporator ion gauge, IEVAPIG1 filament burnt out.  The gauge comes in two filaments, so it is now running on the second one.  The chamber has been pumped down overnight, currently it's @ 2.29e-6 torr. 

Thu May 12 11:15:59 2011:  TGHT was stepped up to 80A, vac @ 2.47e-6 Torr.  Begin auto heating at 1A/min to 820A and will increase the rate to 2A/min if the vacuum is stable. 

Thu May 12 12:27:35 2011:   TGHT went up to 101A, and the vacuum started to reach close to the trip limit (8.7e-6 Torr).  TGHT was auto ramped down but the vacuum kept rising and tripped off the heater @ 94A.  TGHT was turned back on after 30mins, vac @ 8.7e-6 Torr.  TGHT was tapped up slowly to 95A.  The ramping rate has also decreased to 0.5A/min.  (See attachment#1: high_vacuum)

Thu May 12 12:58:51 2011:  Lowered TGHT to 90A.  Vac stayed at 7.8e-5 Torr.

Fri May 13 15:47:42 2011:  TGHT @ 128A, incrementing rate @ 1A/min, Vac @ 5.4e-5 Torr after 30 hrs. (See Attachment#2:  current_pressure_30hrs)

Fri May 13 16:22:54 2011:  THGT and vacuum over the past 12 hrs.  (See Attachment#3: current_pressure_past12hrs)

Mon May 16 11:03:54 2011:  THGT reached to 820A and held for over 12 hrs.   (See Attachment#4_Sintering process). 


Tue May 17 16:26:34 2011

Problem Occurred: 

  • The end caps of the target got vaporized after the sintering process.  (See Attachment#5:  end_caps_vaporized)
  • The caps were not coated with TaC and a D-shaped graphite foil were used. 

Solutions: 

  • The caps were removed - No damage to the target oven.  (See Attachment#6/#7: left_end/ right_end )
  • New caps  were used and coated with TaC.   Two circled-graphite foils were used on the both ends and then sealed with the TaC coated caps. (See Attachment 8: TaC_coated_endcaps)
  • Re-heating the target to 820A.

 


Tue May 17 16:35:13 2011:  Target is wrapped with 3 Ta-heat shields.  The target is in the evaporator which is being pumped down.  

Tue May 17 19:34:55 2011:  TGHT stepped up to 80A, Vac holding at 5.2e-6 Torr.  Auto heating began after 25 mins later.  Rate set at 2A/min to max 820A. 

 Tue May 17 22:02:36 2011:  TGHT @ 382A, Vac @ 1.23 e-5 Torr.  Increased ramping rate @ 3A/min.  Cooling down process will begin at 04:00 of May18, 2011;  ISAC Ops will help to start the auto cooling process.

Wed May 18 11:39:47 2011:  The cooling down process ended; TGHT reached to zero.  The camber will be vented. 


 

Attachment 1: high_vacuum.jpg  343 kB  Uploaded Thursday, May 12, 2011, 13:44  | Show | Hide all
Attachment 2: current_pressure_30hrs.jpg  100 kB  Uploaded Friday, May 13, 2011, 16:50  | Show | Hide all
Attachment 3: current_pressure_past12hrs.jpg  87 kB  Uploaded Friday, May 13, 2011, 17:25  | Show | Hide all
Attachment 4: Sintering_process.jpg  35 kB  Uploaded Monday, May 16, 2011, 12:07  | Show | Hide all
Attachment 5: end_caps_vaporized.jpg  25 kB  Uploaded Tuesday, May 17, 2011, 19:01  | Show | Hide all
Attachment 6: Left_end.jpg  50 kB  Uploaded Tuesday, May 17, 2011, 19:03  | Show | Hide all
Attachment 7: right_end.jpg  27 kB  Uploaded Tuesday, May 17, 2011, 19:03  | Show | Hide all
Attachment 8: TaC_coated_endcaps.jpg  37 kB  Uploaded Tuesday, May 17, 2011, 19:03  | Show | Hide all
Attachment 9: SiC_EDX.jpg  127 kB  Uploaded Wednesday, September 14, 2011, 11:09  | Show | Hide all
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