Nikita Bernier wrote:

Friday, August 10, 2012, 19:54   Target boat with TaC coating, inside covered with a 0.002 inches thick Ta foil, wrapped with a 0.002 inches thick Ta foil, contains a Ta foil with TaO coating. See John's Ipad for their recipes. Evaporator #2 is now auto-ramping overnight at 0.2 A/min, up to 830 A, with the maximum voltage limited at 14 V, between 2.00e-05 (Good vacuum) and 3.00e-05 Torr (Bad vacuum).

 Saturday, August 11, 2012, 19:15

Heating process was going smoothly up to 400 A. See Attachment 1.

Around 420 A, vacuum went up again and the voltage increased more quickly. It seems like resistance is building up. After reaching 530 A, the current was tapped down to 420 A in an effort to save the Ta boat. See Attachment 2.

The current will stay at 420 A for the weekend until John takes a look at this.

Nikita Bernier wrote:

Nikita Bernier wrote:  Friday, August 10, 2012, 19:54   Target boat with TaC coating, inside covered with a 0.002 inches thick Ta foil, wrapped with a 0.002 inches thick Ta foil, contains a Ta foil with TaO coating. See John's Ipad for their recipes. Evaporator #2 is now auto-ramping overnight at 0.2 A/min, up to 830 A, with the maximum voltage limited at 14 V, between 2.00e-05 (Good vacuum) and 3.00e-05 Torr (Bad vacuum).    Saturday, August 11, 2012, 19:15 Heating process was going smoothly up to 400 A. See Attachment 1. Around 420 A, vacuum went up again and the voltage increased more quickly. It seems like resistance is building up. After reaching 530 A, the current was tapped down to 420 A in an effort to save the Ta boat. See Attachment 2. The current will stay at 420 A for the weekend until John takes a look at this.

 Monday, August 13, 2012, 13:46

 TGHT was ramped down at 2 A/min and then tapped down to 0A. See Attachment 1.  The target boat will be cooled down for about an hour before turning off the chiller.

Tuesday, August 14, 2012, 15:01

The Cu-heatshield insulators are broken due to prolong heating time during the target processes (see attachment#1). 

The insulators are replaced with the MM800 type (see attachment #2).

Nikita Bernier wrote:

Nikita Bernier wrote: Nikita Bernier wrote:  Friday, August 10, 2012, 19:54   Target boat with TaC coating, inside covered with a 0.002 inches thick Ta foil, wrapped with a 0.002 inches thick Ta foil, contains a Ta foil with TaO coating. See John's Ipad for their recipes. Evaporator #2 is now auto-ramping overnight at 0.2 A/min, up to 830 A, with the maximum voltage limited at 14 V, between 2.00e-05 (Good vacuum) and 3.00e-05 Torr (Bad vacuum).    Saturday, August 11, 2012, 19:15 Heating process was going smoothly up to 400 A. See Attachment 1. Around 420 A, vacuum went up again and the voltage increased more quickly. It seems like resistance is building up. After reaching 530 A, the current was tapped down to 420 A in an effort to save the Ta boat. See Attachment 2. The current will stay at 420 A for the weekend until John takes a look at this.    Monday, August 13, 2012, 13:46  TGHT was ramped down at 2 A/min and then tapped down to 0A. See Attachment 1.  The target boat will be cooled down for about an hour before turning off the chiller.

 Tuesday, August 14, 2012, 16:56

Summary:

The purpose of this experiment is to test the chemical and high temperature (1600C) resistance of a Ta foil (0.001" thick) coated with Ta2O5, so it can be used as the under-layer for the BeO sintering process.

The Ta2O5 (white powder, -325 mesh) was prepared in a non-aqueous solution and was sprayed on a piece of Ta foil. 

The coated foil was rolled up and inserted in a Ta-coated (previously sintered) target boat for heating.

The foil was heated up to 520A (~1200C) and evidently,Ta2O5 started to react with Ta foil, and the foil became brittle and cracked (see attachment#1).

In conclusion, Ta2O5 is not a good protection layer for Ta material - at least for our applications.

Friday, January 11, 2013, 10:59

The insulator that holds the terminals was broken when a target container was installed.  The insulator had seen so much heat shine from the Cu heat-shield gaps, see attachment.  Tightening the bolts on the target container might further put more force on the insulator and eventually broke it.

To prevent this to happen again.  The Cu-heat shield gaps have covered with Ta-foil to prevent any shine from the target  container onto the insulator.  Also, a torque wrench will be used to tighten the bolts on the terminals.  At this point, we don't know the max torque the insulator can tolerate.  Some measurements were done on the target resistant (ohm) as a function of torque (in pounds).  The best torque to tighten the terminal bolts is 150 lbs. 

John Wong wrote:

Friday, January 11, 2013, 10:59 The insulator that holds the terminals was broken when a target container was installed.  The insulator had seen so much heat shine from the Cu heat-shield gaps, see attachment.  Tightening the bolts on the target container might further put more force on the insulator and eventually broke it. To prevent this to happen again.  The Cu-heat shield gaps have covered with Ta-foil to prevent any shine from the target  container onto the insulator.  Also, a torque wrench will be used to tighten the bolts on the terminals.  At this point, we don't know the max torque the insulator can tolerate.  Some measurements were done on the target resistant (ohm) as a function of torque (in pounds).  The best torque to tighten the terminal bolts is 150 lbs.

The insulators were installed with torques as indicated in the attached PDF ITD0052. A torque test was performed on the broken insulator before installation. No damage was seen on torques of up to 60 in lbs for the 1/4-20 bolts, however for torques in excess of 50 in lbs the insulator material seems to "give".

 Tuesday, January 22, 2013, 12:38

This is to test the newly developed RFQ target to be commissioned this year.  The purpose of this test is to see how well the RFQ components can sustain the high temperature.  One thermocouple is connected inside the target and the other is connect outside of the Cu heat-shield.  RGA will be running to analyze the gasses. 

TGHT will be auto-ramped up at the rate of 5A/20min to max current at 1000A.  

More info later... 

Wednesday, February 06, 2013, 16:11 

Heat testing Test#1 complete.  Data acquisition in progress....  The test was successful. 

Re-heating Test#2 is in progress.  This time, with a new re-design target container (less black block mass).  Two thermocouples are connected:  One on the back block and the other inside the RFQ components.  

The TGHT current will go up to at least 580A and the gasses will be monitored with the RGA. Ramping rate:  0.5A/min.  Set final current at 400A for now. 

TBHT will remain off at this point until we can know the temperature when TGHT is up to 580A.  

 Thursday, February 07, 2013, 11:39

TGHT reached to 400A/6.30V. 

Back block temperature measured at 18.307mV = 1003 C. 

RFQ component temperature measured at  = 143 C.

TGHT will be ramped up to 580A. 

Continue to monitor...

 Saturday, February 09, 2013, 09:40

TGHT at 580A, TBHT at 271A (setpoint).  Seeing CO2 gassing out.  Ramped down TBHT to zero A and continue to monitor.

Tuesday, February 12, 2013, 16:39  

TGHT heated up to 580A and remained at that current over the long weekend.  

The thermocouple on the back block was reading wrong because the wires away from the tip were fused to the container at high current.  (see attachment #1) 

TBHT was ramped up to 300A and then lower to 280A; mass 32 (CH3OH), and 44 (CO2) were detected.  This is unusual at 580A = 1200C. 

Both TBHT and TGHT were ramped down to zero and the outgassing of these molecules continue to detect on the RGA. (see attachment #2).  Suspect of these gasses from the Cu heat-shield or the thermocouple SiO insulator.

For complete process on screenshots, see my dropbox.

Next:  Coat this container with TaC and use for the SiC target.

Tuesday, May 28, 2013, 17:36

The target containers endcaps were coated with TaC solution and let dry. 

Each cap is wrapped with a small piece of graphite foil and inserted in the target boat.

The chamber is currently being pumped down. 

The HS cooling water valve will be opened tomorrow; any leak will be inspected.

When the vacuum is good,  TGHT will be ramped up to 580A. 

 Wednesday, May 29, 2013, 17:06

HS water valve was opened early this morning; no leaks were detected.

TGHT has stepped up to 50A.  IG is currently at 2.0e-6Torr. 

Initiated auto-ramping at 1.0A/min.

 Thursday, May 30, 2013, 11:12

TGHT reached to 580.  The end caps have been heated at that current for more than 7 hrs.

IG is coming down, currently at 8e-7 Torr.

Auto-cooling initiated, ramping down at 2A/min .

Tuesday, August 27, 2013, 16:48

Target boat is filled with TaC coated endcaps (brown) and some partial sinterred ones (gray) from before.  (see attachment#1).

The container is wrapped with Ta heat-shield.

Chamber has been pumped down; IG currently @ 7.3e-7 Torr. 

Heat-shield cooling water valves are open; no leaks are detected.

Initiated TGHT auto-ramping at 0.5A/min, set TGHT max at 580A.

 Wednesday, August 28, 2013, 16:09

TGHT has reached to 580A and been heated for over 4 hours.

IG is coming down, currently at 1.9 e-6 Torr.

Initiated auto-cooling.  2A/min. 

John Wong wrote:

Tuesday, August 27, 2013, 16:48 Target boat is filled with TaC coated endcaps (brown) and some partial sinterred ones (gray) from before.  (see attachment#1). The container is wrapped with Ta heat-shield. Chamber has been pumped down; IG currently @ 7.3e-7 Torr.  Heat-shield cooling water valves are open; no leaks are detected. Initiated TGHT auto-ramping at 0.5A/min, set TGHT max at 580A.  Wednesday, August 28, 2013, 16:09 TGHT has reached to 580A and been heated for over 4 hours. IG is coming down, currently at 1.9 e-6 Torr. Initiated auto-cooling.  2A/min.

 Thursday, August 29, 2013, 11:50

TGHT at 0 A

IG at 3.5e-7 Torr

Turning off EVAP2 and venting chamber

Process complete

 Tuesday, October 29, 2013, 15:50: Pumping down

Wednesday, October 30, 2013, 09:32: Turbo started

Wednesday, October 30, 2013, 14:50: The Cu-bars were heated to 600A and 300A for TGHT and TBHT respectively.

Wednesday, October 30, 2013, 15:17: PS off. Turbo off.

Results can be found on DocuShare and in the attached plot.

The source of the poor vacuum in the backing line seems to be related to a dirty filter. We will try to find a replacement filter next week.

The problem seem to have started September 17th, when backing preassure CG1A went from 40 mTorr to 130 mTorr. CG1B remained around 30 mTorr.

With the help of Anthony Ip from vacuum group, the problem was diagnosed to be the roughing pump itself. The pump was replaced and pumping improved. The chamber can now be evacuated and turbo ready to start in less than 10 minutes.

The filter is not stocked by vacuum group and could not be replaced.

Last week parts of the roughing line was cleaned by Rick. The PVC roughing line has been replaced with a SST bellows. The SST bellows is KF25 and should be replaced by a KF40 bellows in the long run.

See attached photo.

The Heat Shield has been taken to the Machine Shop for repair.

Friday, November 08, 2013

 The Heat Shield cooling line has been repaired and the lid re-installed in the evaporator. Photo attached.

Friday, November 08, 2013, 10:58 : Roughing Started

Friday, November 08, 2013, 11:05: Turbo started 

Friday, November 08, 2013, 11:15: Turbo at speed Vacuum at (IGP1) 5.7E-5 T 

 Tuesday, January 28, 2014, 15:43

The target containers end-caps were coated with TaC spray and let dry.

Each cap is wrapped with a small piece of graphite foil and inserted in the target boat. [see attached photo]

The chamber is currently being pumped down overnight.

 Wednesday, January 29, 2014, 11:32

Chamber was pumped down to 1.6e-7 Torr overnight.

HS cooling water valve opened; no leaks detected.

TGHT was stepped up to 35A, voltage max set at 11.05V. TBHT currently at 0A.

Waited ~20min, current stabilized, vacuum started to drop, auto-ramp initiated at 0.2A/min and max setpoint to 580A.

Good vacuum: 3.00e-5 Torr, Bad vacuum 4.00e-5 Torr.

 Thursday, January 30, 2014, 09:06

TGHT has been slowly ramping up overnight at a rate of 0.2A/min.

IGP1 = 2.4e-7 Torr, TGHT = 283A; stepping ramping rate up to 2.0A/min.

 Thursday, January 30, 2014, 15:53

TGHT reached 580A at 11:45. Measured temp @1650C.

Initiating TGHT auto-cooling now at 2.0A/min.

 Friday, January 31, 2014, 09:04

Chamber cooled down overnight, vented and opened this morning.

Smooth run!

 Friday, January 31, 2014, 11:21

Opened up the end caps, turns out it wasn't such a smooth run...they're not fully sintered 

See attached photo comparison between fully sintered end cap [silver] and end cap from this run [green].

Will re-install and re-sinter next week.

 Wednesday, February 05, 2014, 11:34

End-caps re-installed into EVAP2

Target boat is wrapped with 3 x Ta heat-shield.

Chamber is currently being pumped down.

 Wednesday, February 05, 2014, 14:31

Chamber was pumped down to 5e-7 Torr this morning.

HS cooling water valve opened, no leaks detected.

TGHT was stepped up to 35A, voltage max set at 11.05V. TBHT currently at 0A.

Waited ~20min, current stabilized, vacuum started to drop, auto-ramp initiated at 0.2A/min and max setpoint to 580A.

Good Vacuum: 3.00e-5 Torr, Bad vacuum 4.00e-5 Torr.

 Thursday, February 06, 2014, 09:06

TGHT has been slowly ramping up overnight at a rate of 0.2A/min.

IGP1 = 1.1e-7 Torr, TGHT = 259A; stepping ramping rate up to 2.0A/min.

 Friday, February 07, 2014, 10:10

TGHT reached 580A yesterday. Measured internal temp @ 1500C.

Initiated TGHT auto-cooling this morning at 2.0A/min

 Tuesday, February 11, 2014, 13:30

Vented and opened chamber this morning.

Endcaps are toast  [see pictures attached]

Some of the endcaps broke/fried, others deformed-none useable.

Possibly due to new target boat resulting in more current?

Too much heat with Ta heat shields?

Bad News Bears 

 Tuesday, February 25, 2014, 16:08

The target containers end-caps were coated with TaC spray and let dry.

The caps are inserted in the target boat vertically with no heat shield and no graphite foil. [see attached photo]

The chamber is currently being pumped down overnight.

 Wednesday, February 26, 2014, 09:54

Chamber was pumped down overnight to 4.2e-7 Torr.

HS cooling water valves opened; no leaks detected.

TGHT was stepped up to 35A, voltage max set at 14V. TBHT currently at 0A.

Waited ~20min, current stabilized, vacuum started to drop, auto-ramp initiated at 0.2A/min and max setpoint to 700A.

Will ramp up to 700A rather than the usual 580A due to last round of endcaps not fully sintering at 580A with new target boat design.

Good vacuum: 3.00e-5 Torr; Bad vacuum: 4.00e-5 Torr.

 Thursday, February 27, 2014, 09:38

TGHT has been slowly ramping up overnight at a rate of 0.2A/min.

IGP1 = 2.8e-7 Torr; TGHT = 311A, 4.3V

Stepping ramping rate up to 2.0A/min.

 Friday, February 28, 2014, 08:53

TGHT reached max setpoint of 700A yesterday evening.

Internal temp measured with Mikron = 1700C

IGP1 = 3e-7 Torr 

Power = 12.95V

Initiating auto-cooling at 2.0A/min.

 Monday, March 03, 2014, 11:46

Vented and opened chamber this morning.

End caps not fully sintered! 

See attached photo comparison of fully sintered [grey], partially sintered from this round [light green] and pre-sinter [dark green].

Will not bother re-sintering, as partial sinter is enough.

There was no signal going from the coils to the PLC. After manipulating the connection points on the coil a signal could again be established. Frequency is ~ 40Hz.

 Friday, March 07, 2014, 11:41

The target container end-caps were sintered previously, but did not fully complete the sintering process [See elog entry # 119 EVAP2]

The caps are inserted in the target boat wrapped in graphite foils with 3 x Ta-heat shields.

The chamber was pumped down overnight.

IGP1 = 2e-7 Torr

HS cooling water valves were opened; no leaks detected.

TGHT was stepped up to 35A, voltage max set at 9.05V. TBHT currently at 0A.

 Friday, March 07, 2014, 11:52

Waited ~20min, current stabilized, vacuum started to drop, auto-ramp initiated at 0.5A/min and max setpoint to 500A.

Will ramp to 500A due to last failed round of end caps breaking with 3-ta heat shields at 580A.

Good vacuum: 3.00e-5 Torr; Bad vacuum: 4.00e-5 Torr.

 Friday, March 07, 2014, 13:21

IGP1 = 8e-7 Torr.

TGHT = 72A

Vacuum stable; therefore, increasing ramping rate up to 1.0A/min

 Friday, March 07, 2014, 14:20

IGP1 = 9.8e-7 Torr

TGHT = 130A

Vacuum stable; therefore, increasing ramping rate up to 2.0A/min

Laura Lambert wrote:

Friday, March 07, 2014, 11:41 The target container end-caps were sintered previously, but did not fully complete the sintering process [See elog entry # 119 EVAP2] The caps are inserted in the target boat wrapped in graphite foils with 3 x Ta-heat shields. The chamber was pumped down overnight. IGP1 = 2e-7 Torr HS cooling water valves were opened; no leaks detected. TGHT was stepped up to 35A, voltage max set at 9.05V. TBHT currently at 0A.  Friday, March 07, 2014, 11:52 Waited ~20min, current stabilized, vacuum started to drop, auto-ramp initiated at 0.5A/min and max setpoint to 500A. Will ramp to 500A due to last failed round of end caps breaking with 3-ta heat shields at 580A. Good vacuum: 3.00e-5 Torr; Bad vacuum: 4.00e-5 Torr.  Friday, March 07, 2014, 13:21 IGP1 = 8e-7 Torr. TGHT = 72A Vacuum stable; therefore, increasing ramping rate up to 1.0A/min  Friday, March 07, 2014, 14:20 IGP1 = 9.8e-7 Torr TGHT = 130A Vacuum stable; therefore, increasing ramping rate up to 2.0A/min

Friday, March 07, 2014, 22:22  

Target current was at 500A before it tripped off on the chiller.   Tried to reset the chiller but to no avail.  Don't know what is going on yet. 

The TGHT/TBHT cooling water is still on, and this should OK while the HOT target boat is cooling down at the moment. 

Will leave it for now and further investigate on Monday

Monday, March 10, 2014, 11:44

Rick replaced the backing pump hose from 1.5" to 2.0" for better flow.  And the HEPA filter was checked - it looks OK.