Monday, October 22, 2018, 17:55 

UO2/C green was prepared , September 24, 2018

Initial UO2 powder used = 50.11 g (Inventory R-01032A, UO2 + bottle = 374.03 g before use)

Graphite powder used = 10.13 g

Green cast dried UO2/C + organic mass = 62.45 g 

The green was rolled up and wrapped in a piece of graphite sheet.

The Ta-target boat was wrapped with 3-layers of heat shield [2 reused, 1 new] and installed in evap1.

Currently pumping down.

 Tuesday, October 23, 2018, 15:38

IGP1 = 2.44e-6 Torr,

Tapped to 60 A at 10A/10s with 20 s waiting every 10 A,

Waited 28 min to vacuum to stabilize,

tapped to 80 A at 10A/10s with 20 s waiting every 10 A,

max pressure 7x10-3 Torr, waited 50 min to vacuum to drop

Tapped to 100 A at 10A/10s with 20 s waiting every 10 A,

max pressure 4x10-2 Torr, tapped current to 80 A,

The pressure was dropping, when it was at 2x10-2 Torr, the current tripped off.

IGP1 = 1x10-4 Torr

Tapped back to 60 A at 10A/10s with 20 s waiting every 10 A,

waited 5 min to tap to 80 A at same rate

waited 5 min to tap to 100 A at same rate

waited 25 min to vacuum to drop from 2e-2 Torr to 8e-4Torr

Tapped to 110 A at same rate

Marla Cervantes wrote:

Monday, October 22, 2018, 17:55  UO2/C green was prepared , September 24, 2018 Initial UO2 powder used = 50.11 g (Inventory R-01032A, UO2 + bottle = 374.03 g before use) Graphite powder used = 10.13 g Green cast dried UO2/C + organic mass = 62.45 g  The green was rolled up and wrapped in a piece of graphite sheet. The Ta-target boat was wrapped with 3-layers of heat shield [2 reused, 1 new] and installed in evap1. Currently pumping down  Tuesday, October 23, 2018, 15:38 IGP1 = 2.44e-6 Torr, Tapped to 60 A at 10A/10s with 20 s waiting every 10 A, Waited 28 min to vacuum to stabilize, tapped to 80 A at 10A/10s with 20 s waiting every 10 A, max pressure 7x10-3 Torr, waited 50 min to vacuum to drop Tapped to 100 A at 10A/10s with 20 s waiting every 10 A, max pressure 4x10-2 Torr, tapped current to 80 A, The pressure was dropping, when it was at 2x10-2 Torr, the current tripped off. IGP1 = 1x10-4 Torr Tapped back to 60 A at 10A/10s with 20 s waiting every 10 A, waited 5 min to tap to 80 A at same rate waited 5 min to tap to 100 A at same rate waited 25 min to vacuum to drop from 2e-2 Torr to 8e-4Torr Tapped to 110 A at same rate waited 3 min  to tap to 120 A at same rate waited 1 min  to tap to 130 A at same rate waited 1 min  to tap to 140 A at same rate   waited 15 min to pressure to drop from 6e-2 Torr to 7e-4 Torr   Changing manual rate to 10A/10s with waiting periods of 1 min, current was increased from 140 A to 260 A with this rate.   Changing manual rate to 20A/10s with waiting periods of 30 s, current was increased from 260 A to 480 A with this rate.   Waiting 4 min for the pressure to increase.   Changing the rate to 5A/30s, tapped until 510 A,   Changing the waiting period to 1 min, kept tapping to 530 A,   The pressure was dropping, when it was at 2x10-2 Torr, the current tripped off   The vacuum limit is 5e-1 Torr, and the pressure was dropping, there was no reason for the current to trip.   The pumps seems to be fine in the hot lab.

 Wednesday, October 24, 2018, 17:51

Rod from controls checked on the system, seems that the controls are not the cause of the trip

Rod suggested that the power supply might be overheating, 

thermocouples were installed on the surface of the power supply to register the temperature during the process

Tapping the current up again at accelerated rate see spread sheet for details.

Since pressure was not decreasing the current was increased to 595 A (rate 1A/min) [see figure CT-2]

The power supply's maximum temperature was 32.7 C which is a difference of 9.7 degrees with respect to the initial temperature. 

The target will remain at maximum temperature overnight.

Marla Cervantes wrote:

Marla Cervantes wrote: Monday, October 22, 2018, 17:55  UO2/C green was prepared , September 24, 2018 Initial UO2 powder used = 50.11 g (Inventory R-01032A, UO2 + bottle = 374.03 g before use) Graphite powder used = 10.13 g Green cast dried UO2/C + organic mass = 62.45 g  The green was rolled up and wrapped in a piece of graphite sheet. The Ta-target boat was wrapped with 3-layers of heat shield [2 reused, 1 new] and installed in evap1. Currently pumping down.  Tuesday, October 23, 2018, 15:38 IGP1 = 2.44e-6 Torr, Tapped to 60 A at 10A/10s with 20 s waiting every 10 A, Waited 28 min to vacuum to stabilize, tapped to 80 A at 10A/10s with 20 s waiting every 10 A, max pressure 7x10-3 Torr, waited 50 min to vacuum to drop Tapped to 100 A at 10A/10s with 20 s waiting every 10 A, max pressure 4x10-2 Torr, tapped current to 80 A, The pressure was dropping, when it was at 2x10-2 Torr, the current tripped off. IGP1 = 1x10-4 Torr Tapped back to 60 A at 10A/10s with 20 s waiting every 10 A, waited 5 min to tap to 80 A at same rate waited 5 min to tap to 100 A at same rate waited 25 min to vacuum to drop from 2e-2 Torr to 8e-4Torr Tapped to 110 A at same rate waited 3 min  to tap to 120 A at same rate waited 1 min  to tap to 130 A at same rate waited 1 min  to tap to 140 A at same rate   waited 15 min to pressure to drop from 6e-2 Torr to 7e-4 Torr   Changing manual rate to 10A/10s with waiting periods of 1 min, current was increased from 140 A to 260 A with this rate.   Changing manual rate to 20A/10s with waiting periods of 30 s, current was increased from 260 A to 480 A with this rate.   Waiting 4 min for the pressure to increase.   Changing the rate to 5A/30s, tapped until 510 A,   Changing the waiting period to 1 min, kept tapping to 530 A,   The pressure was dropping, when it was at 2x10-2 Torr, the current tripped off   The vacuum limit is 5e-1 Torr, and the pressure was dropping, there was no reason for the current to trip.   The pumps seems to be fine in the hot lab.  Wednesday, October 24, 2018, 17:51 Rod from controls checked on the system, seems that the controls are not the cause of the trip Rod suggested that the power supply might be overheating,  thermocouples were installed on the surface of the power supply to register the temperature during the process Tapping the current up again at accelerated rate see spread sheet for details. Since pressure was not decreasing the current was increased to 595 A (rate 1A/min) [see figure CT-2] The power supply's maximum temperature was 32.7 C which is a difference of 9.7 degrees with respect to the initial temperature.  The target will remain at maximum temperature overnight.

 Thursday, October 25, 2018, 09:07

Carbothermal reduction completed

IGP1 =  1.22e-5 Torr

Maximum power supply's temperature 33.3 C

Ramping current down at 2 A/min.

Monday, October 29, 2018, 12:30

Transferring  UCx to glove box

Mass = 48.384 g

Thursday, October 11, 2018, 18:06

Target consists of 284 UCx discs, total packing length of 8.0 cm. 

Container was previously coated/sintered with TaC (see elog #417) in Evap#2 with TGHT set to 400A and TBHT 230A, but there was a problem with the readback.  Will ramp up TGHT to 400A to see if the carbonization is complete; if not, additional 50A on TGHT can be applied.

One end-cap is inserted on the right, wrt to the ionizer, and left end is open. 

Vacuum initial setting:

Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr.

pressure level will be monitored accordingly...

Auto-ramping setting

TGHT: 60 wait time, 0.2A/min, final 400A (or addtional of 50 A if required as mentioned above)

TGHT: 60 wait time, 0.2A/min, final 230A.

 Chamber is currently being pumped down.

 Friday, October 12, 2018, 15:35

Chamber has pumped down to 1.8e-6 Torr. 

Stepping up TGHT and TBHT to 40A.

 Friday, October 12, 2018, 17:07

TGHT/TBTH was held at 40A reaching max pressure of 1.7e-5 before slowly coming down. 

Initiated autoramping.

 Thursday, October 18, 2018, 11:10

TGHT reached to 400A/3.98V, pressure is coming down from the upper limit at around 320A which indicated the carbonization is approaching to completion (see attachment#1).  However, two more out-gassing steps are typically observed as TGHT reached around 450 A (see previous UCx conditioning process).  Currently the pressure is at 1.04 e-5 torr. 

Auto-ramping TGHT to 450A at 1A/min, continue to observe the vacuum...

 Thursday, October 18, 2018, 12:57

TGHT reached to 450A/4.6V. Pressure is coming down from 1.6 e-5 Torr. (see attachment#2).  Will remain at this heating current until pressure reached to mid 10-6 torr.

John Wong wrote:

Thursday, October 11, 2018, 18:06 Target consists of 284 UCx discs, total packing length of 8.0 cm.  Container was previously coated/sintered with TaC (see elog #417) in Evap#2 with TGHT set to 400A and TBHT 230A, but there was a problem with the readback.  Will ramp up TGHT to 400A to see if the carbonization is complete; if not, additional 50A on TGHT can be applied. One end-cap is inserted on the right, wrt to the ionizer, and left end is open.  Vacuum initial setting: Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr. pressure level will be monitored accordingly... Auto-ramping setting TGHT: 60 wait time, 0.2A/min, final 400A (or addtional of 50 A if required as mentioned above) TGHT: 60 wait time, 0.2A/min, final 230A.  Chamber is currently being pumped down.  Friday, October 12, 2018, 15:35 Chamber has pumped down to 1.8e-6 Torr.  Stepping up TGHT and TBHT to 40A.  Friday, October 12, 2018, 17:07 TGHT/TBTH was held at 40A reaching max pressure of 1.7e-5 before slowly coming down.  Initiated autoramping.  Thursday, October 18, 2018, 11:10 TGHT reached to 400A/3.98V, pressure is coming down from the upper limit at around 320A which indicated the carbonization is approaching to completion (see attachment#1).  However, two more out-gassing steps are typically observed as TGHT reached around 450 A (see previous UCx conditioning process).  Currently the pressure is at 1.04 e-5 torr.  Auto-ramping TGHT to 450A at 1A/min, continue to observe the vacuum...  Thursday, October 18, 2018, 12:57 TGHT reached to 450A/4.6V. Pressure is coming down from 1.6 e-5 Torr. (see attachment#2).  Will remain at this heating current until pressure reached to mid 10-6 torr.

 Friday, October 19, 2018, 10:00

TRIUMF had a total power outage, the TBHT  and TGHT current had been ramped down already.

Marla Cervantes wrote:

John Wong wrote: Thursday, October 11, 2018, 18:06 Target consists of 284 UCx discs, total packing length of 8.0 cm.  Container was previously coated/sintered with TaC (see elog #417) in Evap#2 with TGHT set to 400A and TBHT 230A, but there was a problem with the readback.  Will ramp up TGHT to 400A to see if the carbonization is complete; if not, additional 50A on TGHT can be applied. One end-cap is inserted on the right, wrt to the ionizer, and left end is open.  Vacuum initial setting: Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr. pressure level will be monitored accordingly... Auto-ramping setting TGHT: 60 wait time, 0.2A/min, final 400A (or addtional of 50 A if required as mentioned above) TGHT: 60 wait time, 0.2A/min, final 230A.  Chamber is currently being pumped down.  Friday, October 12, 2018, 15:35 Chamber has pumped down to 1.8e-6 Torr.  Stepping up TGHT and TBHT to 40A.  Friday, October 12, 2018, 17:07 TGHT/TBTH was held at 40A reaching max pressure of 1.7e-5 before slowly coming down.  Initiated autoramping.  Thursday, October 18, 2018, 11:10 TGHT reached to 400A/3.98V, pressure is coming down from the upper limit at around 320A which indicated the carbonization is approaching to completion (see attachment#1).  However, two more out-gassing steps are typically observed as TGHT reached around 450 A (see previous UCx conditioning process).  Currently the pressure is at 1.04 e-5 torr.  Auto-ramping TGHT to 450A at 1A/min, continue to observe the vacuum...  Thursday, October 18, 2018, 12:57 TGHT reached to 450A/4.6V. Pressure is coming down from 1.6 e-5 Torr. (see attachment#2).  Will remain at this heating current until pressure reached to mid 10-6 torr.    Friday, October 19, 2018, 10:00 TRIUMF had a total power outage, the TBHT  and TGHT current had been ramped down already.

  Sunday, October 21, 2018, 1:00 pm

the pumps went out, and the communication with the IEVAP was recovered on Sunday, the vacuum was 160 mTorr,

the pumps were turned on again.

Marla Cervantes wrote:

Marla Cervantes wrote: John Wong wrote: Thursday, October 11, 2018, 18:06 Target consists of 284 UCx discs, total packing length of 8.0 cm.  Container was previously coated/sintered with TaC (see elog #417) in Evap#2 with TGHT set to 400A and TBHT 230A, but there was a problem with the readback.  Will ramp up TGHT to 400A to see if the carbonization is complete; if not, additional 50A on TGHT can be applied. One end-cap is inserted on the right, wrt to the ionizer, and left end is open.  Vacuum initial setting: Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr. pressure level will be monitored accordingly... Auto-ramping setting TGHT: 60 wait time, 0.2A/min, final 400A (or addtional of 50 A if required as mentioned above) TGHT: 60 wait time, 0.2A/min, final 230A.  Chamber is currently being pumped down.  Friday, October 12, 2018, 15:35 Chamber has pumped down to 1.8e-6 Torr.  Stepping up TGHT and TBHT to 40A.  Friday, October 12, 2018, 17:07 TGHT/TBTH was held at 40A reaching max pressure of 1.7e-5 before slowly coming down.  Initiated autoramping.  Thursday, October 18, 2018, 11:10 TGHT reached to 400A/3.98V, pressure is coming down from the upper limit at around 320A which indicated the carbonization is approaching to completion (see attachment#1).  However, two more out-gassing steps are typically observed as TGHT reached around 450 A (see previous UCx conditioning process).  Currently the pressure is at 1.04 e-5 torr.  Auto-ramping TGHT to 450A at 1A/min, continue to observe the vacuum...  Thursday, October 18, 2018, 12:57 TGHT reached to 450A/4.6V. Pressure is coming down from 1.6 e-5 Torr. (see attachment#2).  Will remain at this heating current until pressure reached to mid 10-6 torr.    Friday, October 19, 2018, 10:00 TRIUMF had a total power outage, the TBHT  and TGHT current had been ramped down already.     Sunday, October 21, 2018, 1:00 pm the pumps went out, and the communication with the IEVAP was recovered on Sunday, the vacuum was 160 mTorr, the pumps were turned on again.

 Monday, October 22, 2018, 9:00

The target was transferred to the Ar glove box.

 Tuesday, October 23, 2018, 10:19

Target was inspected:

- Discs were in place

- Orange coating formed on the open end of target container

Spring was removed, two graphite discs were introduced, end cap was placed.

 Monday, September 03, 2018, 10:17

Graphite insert fully loaded with UCx was loaded into previously TaC coated target container.

No end caps on Ta target container.

Weight of graphite tube + UCx discs = 27.118 g

Currently pumping down in evap1.

Tuesday, September 04, 2018, 10:17 

IGP1 = 4.02e-6 Torr

Tapped up TBHT and TGHT manually to 100 A @1 A/s with pauses of 20 s.

Wait for 40 min to pressure to stabilize.

Max pressure 1.38e-4 Torr.

Final pressure 5.93e-5 Torr.

Tuesday, September 04, 2018, 11:46 

Good vacuum 5e-1 Torr

Bad vacuum 8e-1 Torr

Initiating auto ramp for TGHT @ 10 A/min to a max setpoint of 520 A

Initiating auto ramp for TBHT @ 5 A/min to a max setpoint of 245 A

 After achieving 520 A with auto ramp, manually tapped to 599 A.

Manually tapped back to 550 A.

Marla Cervantes wrote:

Monday, September 03, 2018, 10:17 Graphite insert fully loaded with UCx was loaded into previously TaC coated target container. No end caps on Ta target container. Weight of graphite tube + UCx discs = 27.118 g Currently pumping down in evap1. Tuesday, September 04, 2018, 10:17  IGP1 = 4.02e-6 Torr Tapped up TBHT and TGHT manually to 100 A @1 A/s with pauses of 20 s. Wait for 40 min to pressure to stabilize. Max pressure 1.38e-4 Torr. Final pressure 5.93e-5 Torr. Tuesday, September 04, 2018, 11:46  Good vacuum 5e-1 Torr Bad vacuum 8e-1 Torr Initiating auto ramp for TGHT @ 10 A/min to a max setpoint of 520 A Initiating auto ramp for TBHT @ 5 A/min to a max setpoint of 245 A  Tuesday, September 04, 2018, 12:54  After achieving 520 A with auto ramp, manually tapped to 599 A. Manually tapped back to 550 A.

 Friday, September 21, 2018, 10:21

Ramping down heaters at 2 A/min and 1 A/min for TGHT and TBHT.

Marla Cervantes wrote:

Monday, September 03, 2018, 10:17 Graphite insert fully loaded with UCx was loaded into previously TaC coated target container. No end caps on Ta target container. Weight of graphite tube + UCx discs = 27.118 g Currently pumping down in evap1. Tuesday, September 04, 2018, 10:17  IGP1 = 4.02e-6 Torr Tapped up TBHT and TGHT manually to 100 A @1 A/s with pauses of 20 s. Wait for 40 min to pressure to stabilize. Max pressure 1.38e-4 Torr. Final pressure 5.93e-5 Torr. Tuesday, September 04, 2018, 11:46  Good vacuum 5e-1 Torr Bad vacuum 8e-1 Torr Initiating auto ramp for TGHT @ 10 A/min to a max setpoint of 520 A Initiating auto ramp for TBHT @ 5 A/min to a max setpoint of 245 A  Tuesday, September 04, 2018, 12:54  After achieving 520 A with auto ramp, manually tapped to 599 A. Manually tapped back to 550 A.

 Saturday, September 29, 2018, 20:52

Target is taken out from the chamber and transferred to the Ar glove box.

Saturday, September 29, 2018, 18:52

Cast is from Jar#1.  (see process sheet for details)

Target boat contains about 50g UO2 powder. 

TGHT will be ramped up to 520A; fast tapping can be done, see elog#211, or set to autoramping with higher vacuum limit (1setup UCx process with pressure up to 60mTorr, see elog #210)

Chamber is currently being pumped down

 Saturday, September 29, 2018, 21:21

Pressure at 2.6e-5 Torr.

Tapping up TGHT in process

 Saturday, September 29, 2018, 21:32

Tapped to 80A/0.65V.  Wait for vacuum to stabilize.

 Saturday, September 29, 2018, 21:42

Pressure stabilized at 2.5mTorr.

Tapping up to 90A/0.701V

Saturday, September 29, 2018, 21:44

Pressure stabilized at 2.7m Torr; tapping up to 100A/0.77V

Saturday, September 29, 2018, 23:57

TGHT at 520A/4394V (see attachment for striptool capture).  Pressure at 163mTorr and coming down.

 Sunday, September 30, 2018, 12:56

At around midnight, pressure was coming down from 160 mTorr to 21 mTorr before TGHT tripped off (see attachment#2).

I suspect the TP was working too hard causing it to trip.

Pressure at 2.1e-6 Torr. 

Using auto-ramping.  Set good vac at 2.0e-4 Torr, bad vac at 5.0e-4 Torr.  Ramping TGHT at 2A/min to reah 520A.

 Sunday, September 30, 2018, 17:11

Pressure limiting at 0.2 mTorr as TGHT slowly ramping up, currently at 442A;  (see attachment#3).

 Monday, October 01, 2018, 21:15

TGHT was held at 520A for at least a day.  Vac at 3.7e-6 Torr.  Ramping down TGHT at 2A/min.

 Friday, August 17, 2018, 11:17

Four discs of UCx produced with the 1-step casting method were placed in a glass jar.

The mass of the discs was 0.400 g.

The glass jar with the discs were placed in the heating chamber of the IEVAP.

Currently IEVAP is pumping down until vacuum is in the order of  ~10^-6 Torr.

Friday, August 17, 2018, 16:28 

Final vacuum: 9.5x10^-6 Torr

IEVAP's heating chamber will be vented with air and the materials will be taken out.

 Friday, August 17, 2018, 17:27

Material was transferred to the glove box

Friday, August 03, 2018, 17:44

Target consists of 230 UCx discs, total packing length of 7.1cm. 

Container was previously coated/sintered with TaC (see elog #415) in Evap#2 with TGHT set to 450A/7.5V and TBHT 230A/4.2

Vacuum initial setting:

Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr.

pressure level will be monitored accordingly...

Auto-ramping setting

TGHT: 60 wait time, 0.2A/min, final 450A

TGHT: 60 wait time, 0.2A/min, final 230A.

Chamber is currently being pumped down.Good

 Monday, August 06, 2018, 00:04

Pressure at 3.6e-6 Torr. 

Initiate autoramping.

 Friday, August 10, 2018, 11:02

TGHT/TBHT have been at 450A(4.5V)/230A(2.9) for over 15 hours.

Pressure is stabilized at 5.2e-6 Torr. 

Initiated auto-cooling at 2A/min for TGHT and 1A/min for TBHT.

Wednesday, July 11, 2018, 17:41

Cast prepared by Marla (see note in Hotlab)

Target boat contained about 50g UO2 powder. 

TGHT will be ramped up to 520A.

Vacuum limit stop at 3.0 e-4 Torr, backing off at 6.0e-4 Torr. 

Chamber is currently being pumped down

 Thursday, July 12, 2018, 10:45

Pressure at 8.9e-7 Torr. 

Initiate auto ramping TGHT at 0.1A/min to reach 580A (will monitor vacuum to ensure complete carbonization)

 Wednesday, July 18, 2018, 10:23

TGTH at 369A/3.7V, carbonization in progress. 

Pressure limited was set to 5.0e-5 Torr; change limit to 6e-4 Torr (as indicated above)

Increase ramping rate to 0.2A/min.

 Thursday, July 19, 2018, 12:12

Completion of the U-carbonization has been reached. 

Cooling down TGHT at 2A/min

Chamber will be vented in Ar and materials will be transferred to Ar glovebox

Thursday, July 05, 2018, 13:24

Target container was previously coated and sintered with TaC, also wrapped with Ta heat shields (see Evap2 elog# 410).

Loaded 201 discs of UCx with 7.27 cm in length + 5 extra discs for QC samples. 

One end-cap (coated/sintered TaC) inserted right, wrt the ionizer tube pointing down.

Left side is OPEN; a spring is inserted to hold the discs in place.

Chamber is currently being pumped down. 

TGHT will be ramped up to 495A/8.85V and TBHT to 230A/3.26V (same parameters used for sintering the container, evap2 elog#410).

Vacuum initial setting:

Good Vac = 5.0 e-5 Torr, Bad vac = 8.0 e-5 Torr.

pressure level will be monitored accordingly...

Auto-ramping setting

TGHT: 60 wait time, 0.2A/min, final 495A

TGHT: 60 wait time, 0.2A/min, final 230A.

 Thursday, July 05, 2018, 16:50

Tapping up TGHT to 40 A/0.49 V and TGHT to 40A/0.64V.

Vac slowly increasing from 5.0 e-6 Torr. 

Initiate auto-heating

 Tuesday, July 10, 2018, 10:46

Holding TGHT at 495A/5.3V for over 25 hours.  Pressure at 2.9e-6 Torr.

Initiate autocooling TGHT at 2A/min, TBHT 1.0A/min

 Wednesday, July 11, 2018, 17:12

Target was removed from the Evap; it is now in the Ar glovebox.  End cap is inserted. 

Target is ready for installation.

 Tuesday, June 26, 2018, 09:30. Gloves on evap 1 changed out. 

The original right one was otrn. Left was o but worn. Both replaced with new gloves.

 Friday, June 15, 2018, 16:39

35 circles of 14 mm diameter of cast #3 were packed into a graphite sample container.

35 x UO₂/C circles = 4.07 g

Graphite container mass = 5.3 g

Graphite tube is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1.

Chamber currently pumping down.

 Saturday, June 16, 2018, 15:00

Tapped to 80A at 10A/10s with 20 s waiting period each 10 A

Waited 5 min for vacuum to stabilize.

Tapped to 90 A at 10A/10s with 20 s waiting period each 10 A

Waited 14 min for vacuum to stabilize

Tapped to 100 A at 10A/10s with 20 s waiting period each 10 A

Tapped to 520 A at 20A/20s with 20 s waiting period each 20 A

 Tuesday, June 19, 2018, 15:51 

 The material will be in the evap for a week

Wednesday, June 27, 2018, 09:53 

 The IEVAP  was vented with Ar and the UCx was trasnferred to the glove box.

 Tuesday, June 12, 2018, 18:20

35 circles of 14 mm diameter of cast #4 were packed into a graphite sample container.

30 x UO₂/C circles = 4.07 g

Graphite container mass = 5.3 g

Graphite tube is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1.

Chamber currently pumping down.

Wednesday, June 13, 2018, 10:29 

Initial IGP1 = 6.43e-7 Torr

Tapped to 80A at 10A/10s with 20 s waiting period each 10 A

Waited 5 min for vacuum to stabilize.

Tapped to 90 A at 10A/10s with 20 s waiting period each 10 A

Waited 5 min to tap to 100 A 

Waited 14 min for vacuum to stabilize

Tapped to 400 A at 25A/30s with 30 s waiting period each 25 A

Tapped to 520 A at 20A/30s with 30 s waiting period each 20 A

Max pressure ~0.06 Torr 

Marla Cervantes wrote:

Tuesday, June 12, 2018, 18:20 35 circles of 14 mm diameter of cast #4 were packed into a graphite sample container. 30 x UO2/C circles = 4.07 g Graphite container mass = 5.3 g Graphite tube is placed inside a target boat. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1. Chamber currently pumping down. Wednesday, June 13, 2018, 10:29  Initial IGP1 = 6.43e-7 Torr Tapped to 80A at 10A/10s with 20 s waiting period each 10 A Waited 5 min for vacuum to stabilize. Tapped to 90 A at 10A/10s with 20 s waiting period each 10 A Waited 5 min to tap to 100 A  Waited 14 min for vacuum to stabilize Tapped to 400 A at 25A/30s with 30 s waiting period each 25 A Tapped to 520 A at 20A/30s with 30 s waiting period each 20 A Max pressure ~0.06 Torr

 Wednesday, June 13, 2018, 11:08

Pressure was dropping indicating full carbothermal reduction but the current tripped off to 0 A.

Marla Cervantes wrote:

Marla Cervantes wrote:  Tuesday, June 12, 2018, 18:20 35 circles of 14 mm diameter of cast #4 were packed into a graphite sample container. 30 x UO2/C circles = 4.07 g Graphite container mass = 5.3 g Graphite tube is placed inside a target boat. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1. Chamber currently pumping down. Wednesday, June 13, 2018, 10:29  Initial IGP1 = 6.43e-7 Torr Tapped to 80A at 10A/10s with 20 s waiting period each 10 A Waited 5 min for vacuum to stabilize. Tapped to 90 A at 10A/10s with 20 s waiting period each 10 A Waited 5 min to tap to 100 A  Waited 14 min for vacuum to stabilize Tapped to 400 A at 25A/30s with 30 s waiting period each 25 A Tapped to 520 A at 20A/30s with 30 s waiting period each 20 A Max pressure ~0.06 Torr   Wednesday, June 13, 2018, 11:08 Pressure was dropping indicating full carbothermal reduction but the current tripped off to 0 A.

 Wednesday, June 13, 2018, 12:23

The problem was reported to controls group

After 1 hour at 0 A, the autoramp was set to 4 A/min up to 520 A

The current and voltage are increasing accordingly.

The material will stay 4 hours at max point.

Thursday, June 14, 2018, 09:14 

After 4 hours the auto ramp was set to -1A/min to 0 A

Thursday, June 14, 2018, 14:47 

The IEVAP  was vented with Ar and the UCx was trasnferred to the glove box.

 Friday, June 01, 2018, 11:20

Target boat was previously coated with TaC and sintered.

Two small C-inserts of ~2cm length were placed on Ta boat

Sample 1-sc: 15 discs of cast 3 made with 1-step cast method (UCx+foil 1.437 g)

Sample 2-sc: 24 discs from rejected discs of 2-step casting (UCx+foil 1.585 g)

Ta boat was wrapped with 3 layers of Ta-heat shield

The chamber is currently pumping down.

TGHT will be ramped up to 495A [same parameters used to reach 1910C in evap2 when sintering TaC coating - elog410 evap2]

Monday, June 04, 2018, 11:27 

IG1 = 4e-7 Torr

Tapped up manually to 35A

Waited 1hr

Vacuum stable.

IG1 = 8.02e-7 Torr.

Initiating auto-ramp (0.1 A/min) up to 80 A

 Tuesday, June 07, 2018, 15:47

Vacuum stable

IG1 = 7.02e-7 Torr.

Changing auto-ramp to 0.02 A/min up to 140 A

Thursday, June 07, 2018, 15:49 

Vacuum stable 5.5e-7 Torr

Current 139 A, voltage 1.25 V

Changing auto-ramp to 0.1 A/min up to 495 

Saturday, June 9, 2018, 10:41 

The material stayed 4 hours at 495 A

Auto-ramp set to -1 A/min down to 0 A 

Monday, June 11, 2018, 17:43 

EVAPI was vented with Ar and UCx was transferred to glove box

Friday, May 25, 2018, 15:34 

D-shaped discs were cut from cast 3

A 13mm punch was used to punch out discs from pre-cut strips using the old method.

The target consists of 205 discs with 10 cm in length - all single discs, no packs.

205 x UO₂/C discs = 22.04 g

Graphite insert with caps is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3-layers of heat shield and installed in evap1.

Chamber is pumping down.

 Saturday, May 26, 2018, 10:39

Current tapped manually to 80 A at 1A/s in 10 A blocks with a waiting period of 20 s between each increment

18 min waiting for pressure stabilization

Current tapped to 100 A in same rate

Saturday, May 26, 2018, 10:51 

After 9 min current was reduced to 60 A to reduce pressure.

Cuerrent was tapped to 100 A

After 10 min the rate was increased to 25 A each 20 s until 450 A

The rate was changed to 10 A each 2 min until 500 A

Last 20 A were tapped after 1 min 

Saturday, May 26, 2018, 15:41 

After 4hrs the current was reduced in a rate of 10 A /min

Monday, May 28, 2018, 12:45 

EVAPI was vented with Ar and UCx was transferred to glove box.

 Friday, May 18, 2018, 18:32

35 circles of 14 mm diameter of cast #3 were packed into a graphite sample container.

40 x UO2/C circles = 4.58 g

Graphite container mass = 6.95 g

Graphite tube is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1.

Chamber currently pumping down.

Saturday, May 19, 2018, 07:30 

Initial IGP1 = 6.27e-7 Torr

 Tapped to 80A at 10A/10s with 20 s waiting period each 10 A

 Waited 4 min for vacuum to stabilize.

 Tapped to 100 A at 10A/10s with 20 s waiting period each 10 A

 Waited 12 min for vacuum

Tapped to 400 A at 25A/30s with 30 s waiting period each 25 A

Tapped to 520 A at 20A/30s with 30 s waiting period each 20 A

Pressure dropping indicates carbonization complete.

Current tripped off, vacuum was ok, water cooling was ok.

Saturday, May 19, 2018, 10:00 

Current was returned to 520 A manually

Tapped to 100 A at 10A/10s with 20 s waiting period each 10 A 

Tapped to 400 A at 25A/30s with 30 s waiting period each 25 A

Tapped to 520 A at 20A/30s with 30 s waiting period each 20 A

The discs will stay at max current for 4 hrs

 Saturday, May 19, 2018, 18:31

Vented with Argon and removed form evaporator 1

 Thursday, May 10, 2018, 16:00 

Graphite insert fully loaded with UCx was loaded into previously TaC coated target container.

No end caps on Ta target container.

Weight of graphite tube + UCx discs = 27 g

Currently pumping down in evap1.

Friday, May 11, 2018, 11:41 

IGP1 = 1.13e-6 Torr

Good vac at 3.0e-4, bad vac at 6.0e-4 Torr.

Tapped up manually to 100A.

Pressure increased to ~2e-5 Torr

Vacuum stabilized after 40 min

IGP1 = 1e-5 Torr

Initiating auto ramp for TGHT @ 20 A/min to a max setpoint of 520 A

Initiating auto ramp for TBHT @ 10 A/min to a max setpoint of 245 A

Preassure increased o 1e-4 Torr and the auto ramp was aborted

After 8 min IGP1 = 3e-5 Torr

Initiating auto ramp for TGHT @ 10 A/min to a max setpoint of 520 A

Initiating auto ramp for TBHT @ 5 A/min to a max setpoint of 245 A

The vacuum is more stable.

TBHT reached 230 A at 13:00

TGHT reached 520 A at 13:24

Final pressure 1.15e-4 Torr

Target will stay at max current point for a week.

 Friday, May 18, 2018, 18:31

Evap1 was vented in Ar and UCx target was transferred to the glove box

 Tuesday, April 17, 2018, 10:30

UO2/C green was prepared April 12th, 2018

The cast peeled off the glass nicely April 13th, 2018

Initial UO2 powder used = 50.56g (Inventory R-01032A, UO2 + bottle = 626.28g before use)

Graphite powder used = 10.38g

Green cast dried UO2/C + organic mass = 61.40g 

The green was rolled up and wrapped in a piece of graphite sheet.

The Ta-target boat was wrapped with 3-layers of heat shield [1 reused, 2 new] and installed in evap1 yesterday.

Chamber pumped down overnight.

IGP1 = 8.4e-7 Torr

Tapped up to 35A, 0.46V

Waited ~135min, vacuum stable.

IGP1 = 1.6e-5 Torr

Initiating auto-ramp at 0.2A/min

Target boat will be ramped up to 520A.

Vacuum limit stop at 3.0e-4 Torr, backing off at 6.0e-4 Torr.

 Wednesday, April 18, 2018, 09:21

IGP1 = 9.6e-6 Torr

TGHT = 245A, 2.10V

Vacuum stable, increasing ramping rate to 0.5A/min.

 Thursday, April 19, 2018, 08:35

IGP1 = 3.21e-6 Torr

Materials have finished carbonizing.

TGHT = 520A, 4.97V

Evap1 has remained at max setpoints for ~6.5hrs

Initiating auto-cool at 1.0A/min

 Thursday, May 10, 2018, 10:33

Materials were vented in Ar and transferred to glove box on April 20th

 Wednesday, March 28, 2018, 11:35

D-shaped discs were cut from cast 2, the same as the last sample of 1stepUCx [see elog i.d. 197]

A 13mm punch was used to punch out discs from pre-cut strips using the old method.

The target consists of 195 discs with 8.1cm in length - all single discs, no packs.

195 x UO2/C discs = 19.79g

Graphite insert is placed inside a target boat with both endcaps on.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3-layers of heat shield and installed in evap1 yesterday afternoon.

Chamber pumped down overnight.

 Wednesday, March 28, 2018, 13:33

IGP1 = 4.03e-7 Torr

Tapped up TGHT manually to 80A, 0.83V - waited 50min, vacuum started to drop/stabilize.

Continued to tap up manually to 430A, 4.22V

Started out slow with a rate of ~10A/5min, and slowly increased to a rate of ~10A/min as vacuum stabilized, slowing down again when reaching carbonization outgassing.

Auto ramp at 0.2A/min from 430A-520A.

Thursday, March 29, 2018, 10:04

Reached 520A around 2am.

TGHT = 520A, 5.13V

IGP1 = 1.74e-6 Torr

Initiated auto-cool this morning at a rate of 1.0A/min.

Laura Lambert wrote:

Wednesday, March 28, 2018, 11:35 D-shaped discs were cut from cast 2, the same as the last sample of 1stepUCx [see elog i.d. 197] A 13mm punch was used to punch out discs from pre-cut strips using the old method. The target consists of 195 discs with 8.1cm in length - all single discs, no packs. 195 x UO2/C discs = 19.79g Graphite insert is placed inside a target boat with both endcaps on. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3-layers of heat shield and installed in evap1 yesterday afternoon. Chamber pumped down overnight.  Wednesday, March 28, 2018, 13:33 IGP1 = 4.03e-7 Torr Tapped up TGHT manually to 80A, 0.83V - waited 50min, vacuum started to drop/stabilize. Continued to tap up manually to 430A, 4.22V Started out slow with a rate of ~10A/5min, and slowly increased to a rate of ~10A/min as vacuum stabilized, slowing down again when reaching carbonization outgassing. Auto ramp at 0.2A/min from 430A-520A. Thursday, March 29, 2018, 10:04 Reached 520A around 2am. TGHT = 520A, 5.13V IGP1 = 1.74e-6 Torr Initiated auto-cool this morning at a rate of 1.0A/min.

 Monday, April 09, 2018, 16:00

ISAC controls performed a PLC switch over compromising the nuclear ventilation controls WITHOUT NOTIFYING ME  

This is the 2nd time in a month this has happened without being notified.

Evap1 has therefore tripped.

During this switch there was a problem which caused the turn over to take even longer.

Sat here tapping reset until nuclear ventilation was 'back on'.

Vacuum proceeded to drop once the tests were complete, then started to spike again, nuc vent remained not ok after tests were done nuc vent ok.

Laura Lambert wrote:

Laura Lambert wrote:  Wednesday, March 28, 2018, 11:35 D-shaped discs were cut from cast 2, the same as the last sample of 1stepUCx [see elog i.d. 197] A 13mm punch was used to punch out discs from pre-cut strips using the old method. The target consists of 195 discs with 8.1cm in length - all single discs, no packs. 195 x UO2/C discs = 19.79g Graphite insert is placed inside a target boat with both endcaps on. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3-layers of heat shield and installed in evap1 yesterday afternoon. Chamber pumped down overnight.  Wednesday, March 28, 2018, 13:33 IGP1 = 4.03e-7 Torr Tapped up TGHT manually to 80A, 0.83V - waited 50min, vacuum started to drop/stabilize. Continued to tap up manually to 430A, 4.22V Started out slow with a rate of ~10A/5min, and slowly increased to a rate of ~10A/min as vacuum stabilized, slowing down again when reaching carbonization outgassing. Auto ramp at 0.2A/min from 430A-520A. Thursday, March 29, 2018, 10:04 Reached 520A around 2am. TGHT = 520A, 5.13V IGP1 = 1.74e-6 Torr Initiated auto-cool this morning at a rate of 1.0A/min.    Monday, April 09, 2018, 16:00 ISAC controls performed a PLC switch over compromising the nuclear ventilation controls WITHOUT NOTIFYING ME   This is the 2nd time in a month this has happened without being notified. Evap1 has therefore tripped. During this switch there was a problem which caused the turn over to take even longer. Sat here tapping reset until nuclear ventilation was 'back on'. Vacuum proceeded to drop once the tests were complete, then started to spike again, nuc vent remained not ok after tests were done nuc vent ok.

 Monday, April 09, 2018, 16:52

Turns out I wasn't on a list of ppl who need to know about this test when I should be

They also didn't reset the alarms locally outside the hot lab so nuc vent remained not ok until this was reset.

IGP1 reached 0.027 Torr before nuc vent was ok and pumps were able to be turned back on 

Pumps back on IGP1 = 1.86e-5 Torr and still pumping down

Laura Lambert wrote:

Laura Lambert wrote: Laura Lambert wrote:  Wednesday, March 28, 2018, 11:35 D-shaped discs were cut from cast 2, the same as the last sample of 1stepUCx [see elog i.d. 197] A 13mm punch was used to punch out discs from pre-cut strips using the old method. The target consists of 195 discs with 8.1cm in length - all single discs, no packs. 195 x UO2/C discs = 19.79g Graphite insert is placed inside a target boat with both endcaps on. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3-layers of heat shield and installed in evap1 yesterday afternoon. Chamber pumped down overnight.  Wednesday, March 28, 2018, 13:33 IGP1 = 4.03e-7 Torr Tapped up TGHT manually to 80A, 0.83V - waited 50min, vacuum started to drop/stabilize. Continued to tap up manually to 430A, 4.22V Started out slow with a rate of ~10A/5min, and slowly increased to a rate of ~10A/min as vacuum stabilized, slowing down again when reaching carbonization outgassing. Auto ramp at 0.2A/min from 430A-520A. Thursday, March 29, 2018, 10:04 Reached 520A around 2am. TGHT = 520A, 5.13V IGP1 = 1.74e-6 Torr Initiated auto-cool this morning at a rate of 1.0A/min.    Monday, April 09, 2018, 16:00 ISAC controls performed a PLC switch over compromising the nuclear ventilation controls WITHOUT NOTIFYING ME   This is the 2nd time in a month this has happened without being notified. Evap1 has therefore tripped. During this switch there was a problem which caused the turn over to take even longer. Sat here tapping reset until nuclear ventilation was 'back on'. Vacuum proceeded to drop once the tests were complete, then started to spike again, nuc vent remained not ok after tests were done nuc vent ok.    Monday, April 09, 2018, 16:52 Turns out I wasn't on a list of ppl who need to know about this test when I should be They also didn't reset the alarms locally outside the hot lab so nuc vent remained not ok until this was reset. IGP1 reached 0.027 Torr before nuc vent was ok and pumps were able to be turned back on  Pumps back on IGP1 = 1.86e-5 Torr and still pumping down

 Tuesday, April 10, 2018, 14:46

Glove box fixed!

Vented in Argon and transferred to glove box.

Graphite insert has moved to within 1mm of the end of the left side of the boat.

This could have happened during removal from evap1, hard to tell.

Either way, clearly a looser fit of the graphite insert in the boat indicating possible shrinkage of graphite insert.

 Tuesday, March 20, 2018, 14:43

Target container was previously coated with TaC and sintered.

Container is wrapped with 3 layers of Ta-heat shield, including the center block

The target consists of 230 discs of UCx with 7.28cm in length [6 packs of 5 + 200 single discs].

Discs in target are arranged as follows: 1pack / 55singles / 1pack / 50singles / 2packs / 50singles / 1pack / 45singles / 1pack

A regular TaC coated endcap is inserted left, wrt the ionizer tube pointing down.

The right side is open with a TaC coated spring to help hold materials in.

An extra 5 single discs are loaded on the right side on top of the last pack, these discs will be removed after conditioning and analysed using SEM and XRD

The chamber is currently pumping down.

TGHT will be ramped up to 445A and TBHT will be ramped up to 230A [same parameters used to reach 1900C in evap2 when sintering TaC coating - elog402 evap2]

NOTE: This will be the first UCx target to go online using the TBHT in evap1 after the target is loaded with materials.

 Wednesday, March 21, 2018, 09:37

IGP1 = 2.47e-6 Torr

Tapped up manually to 40A.

TGHT = 40A, 0.61V

TBHT = 40A, 0.78V

Waited ~1hr, vacuum stable IG1 = 9.3e-6 Torr

Initiating auto-ramp for TGHT at a rate of 0.2A/min

Initiating auto-ramp for TBHT at a rate of 0.1A/min

Parameter setup: 5.0e-5 good vac, 8.0e-5 bad vac.

Wednesday, March 21, 2018, 13:02

TGHT = 57A, 0.72V

TBHT = 48A, 0.85V

IG1 = 5.8e-5 Torr

Vacuum stable.

Changing vacuum limits.

Vacuum limit stop at 3.0e-4 Torr, backing off at 6.0e-4 Torr.

 Monday, March 26, 2018, 09:32

TGHT = 450A, 4.54V

TBHT = 230A, 2.75V

IGP1 = 8.99e-7 Torr

Target has remained at max setpoint over weekend.

Initiating auto-cool at 1.0A/min for the TGHT and 0.5A/min for the TBHT.

 Wednesday, March 28, 2018, 11:31

Evap1 was vented in Ar and transferred to the glove box yesterday.

Inspection of target still required as well as 2nd endcap to be inserted.

 Monday, March 12, 2018, 9:13

35 circles from cast#2 of 14 mm diameter were packed into a graphite sample container.

35 x UO2/C circles = 5.21 g

Graphite container = 6.85 g

Graphite tube is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3 Ta foils for heat shielding and the boat was installed in Evap1.

Chamber currently pumping down.

 Monday, March 12, 2018, 13:57

Initial IGP1 = 4.79e-7 Torr

Tapped up entire process manually to 520A in 30 min

TGHT = 520 A, 5.32 V

Vacuum coming down indicating carbonization process complete.  

Will remain at max setpoint for 1 hrs to ensure full carbonization before cooling down.

 Monday, March 12, 2018, 14:57 

Cooling down rate used 3 A/10s.

 Tuesday, March 13, 2018, 18:22

Vented with Ar and removed from EVAP1

 Tuesday, February 13, 2018, 11:39

35 circles of 14 mm diameter were packed into a graphite sample container.

35 x UO2/C circles = 5.74 g

Graphite container = 5.20 g

Graphite tube is placed inside a target boat.

Boat previously coated with TaC and sintered.

Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1.

Chamber currently pumping down.

 Tuesday, February 13, 2018, 15:30

Initial IGP1 = 2.73x10e-6 Torr

Tapped up entire process manually to 520 A in 30 min

TGHT = 520 A, 5.41 V

Vacuum coming down nicely indicating carbonization process complete.

Current trip off after 5 min of being at 520 A.

 Wednesday, February 14, 2018, 15:32

EVAP1 vented with Argon and the target was removed.

Target was transferred to glove box.

Ta boat and graphite container look unbroken.

Marla Cervantes wrote:

Tuesday, February 13, 2018, 11:39 35 circles of 14 mm diameter were packed into a graphite sample container. 35 x UO2/C circles = 5.74 g Graphite container = 5.20 g Graphite tube is placed inside a target boat. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1. Chamber currently pumping down.  Tuesday, February 13, 2018, 15:30 Initial IGP1 = 2.73x10e-6 Torr Tapped up entire process manually to 520 A in 30 min TGHT = 520 A, 5.41 V Vacuum coming down nicely indicating carbonization process complete. Current trip off after 5 min of being at 520 A.  Wednesday, February 14, 2018, 15:32 EVAP1 vented with Argon and the target was removed. Target was transferred to glove box. Ta boat and graphite container look unbroken.

 Friday, March 02, 2018, 16:31

A test was performed in EVAP1 (see log ID 194):

- A Ta boat without Ta shielding was submitted to 520 A and it remained at that current point overnight.

-No trip off

Marla Cervantes wrote:

Marla Cervantes wrote:  Tuesday, February 13, 2018, 11:39 35 circles of 14 mm diameter were packed into a graphite sample container. 35 x UO2/C circles = 5.74 g Graphite container = 5.20 g Graphite tube is placed inside a target boat. Boat previously coated with TaC and sintered. Ta-target boat is wrapped with 3 used Ta foils for heat shielding and the boat was installed in Evap1. Chamber currently pumping down.  Tuesday, February 13, 2018, 15:30 Initial IGP1 = 2.73x10e-6 Torr Tapped up entire process manually to 520 A in 30 min TGHT = 520 A, 5.41 V Vacuum coming down nicely indicating carbonization process complete. Current trip off after 5 min of being at 520 A.  Wednesday, February 14, 2018, 15:32 EVAP1 vented with Argon and the target was removed. Target was transferred to glove box. Ta boat and graphite container look unbroken.  Friday, March 02, 2018, 16:31 A test was performed in EVAP1 (see log ID 194): - A Ta boat without Ta shielding was submitted to 520 A and it remained at that current point overnight. -No trip off