John Wong wrote:

John Wong wrote: Laura Lambert wrote: Thursday, September 24, 2015, 08:39 IGP1 = 6.5e-7Torr HS water valves opened, no leaks detected. Tapped up manually to 35A. Waited ~20min. Vacuum stable, IGP1 = 1.5e-6 Torr. Initiated auto-ramp at 0.2A/min and 0.1A/min for the TGHT and TBHT respectively with final setpoints of 250A and 230A. Final temp of 1200C on auto-ramp in order to initiate temperature measurements starting at ~1200C. Thursday, September 24, 2015, 10:24   IGP1 = 8.7e-7 Torr TGHT = 44A, TBHT = 38A Increasing auto-ramp to 0.5A/min and 0.2A/min for the TGHT and TBHT respectively.      Thursday, September 24, 2015, 12:04  A few notes about the target container:The Ta-foil is cut in a full length of the target container, and that also covers up the back block, and the container is wrapped with 3 sheets (see attachment)  The inner tube is coated with TaC, using the "flushing technique" - the coating looks much better; will see how it turns out after the sintering process The target will be heated up to 1900C .  Due to the new wrapping of the Ta-heat shield, the heat distribution may be different.  So the target heater will be ramped up to achieve the desired temperature.   Thursday, September 24, 2015, 18:45   TGHT reached to 250A3.6V, TGHT at 230A and stayed for 1.5 hours.  Temp-L = 1280C, Temp-R = 1360C.   Auto-ramp TGHT to 500A at 1A/min and heat at that current for overnight.  Will take temp reading tomorrow.   Thursday, September 24, 2015, 23:08   TGHT has reached to 500A/8.57V.  Temp-L = 1895C, Temp-R = 2073C. (Not sure why the temperature is real, will need to investigate more to get an absolute temp) Just to be safe… Ramping down TGHT to 425A (according to e-log id 216, Temp-R reached to 1800C with TGHT at 425A/6.84V, but no temp measured for the left at that time) Will check again later. Friday, September 25, 2015, 11:52   The target has been heated at 420A for ~12hours; temp measured ~1900C, slightly higher than the previous target container (W.O#40860-1); the Ta-wraping could affect the heat distribution.   The temperature is also confirmed by using the 2-C digital pyrometer.  The tube inner surface is measured about 1900C, and the ionizer tube is about 2400C.  (see attachment #2). Initiating auto-cooling at 2A/min for TGHT and 1A/min for TBHT. The target will be inspected next Monday  Wednesday, September 30, 2015, 16:01 The target container is fully sintered (see attachment#3)  It is still in the discussion where this container will be used online for the UCx.  Nevertheless, the target contain is ready and it looks pretty good.     Tuesday, October 06, 2015, 15:09 After further discussion, we are going to reheat this container to 420A.  The temperature will be measured with the thermocouple - probe inside the centre of the tube - and the 2C-IR for comparison.  This test is to ensure that the container is actually heated to 1900C before the UCx material can be loaded The chamber has been pumped down to 1.92e-6 Torr.  Heat shield valve is open and no leaks are detected.  Ramping up TBHT to 230A max and TGHT to achieve ~1900C  Wednesday, October 07, 2015, 11:12 Yesterday... TBHT ramped up to 230A and TGHT was at 160A before taking temperature readings.  TGHT from 160A to 423A, IR2C temp reading increases linearly from 1138C to 1900C, whereas the thermocouple readouts are not quite linear, 1040C to 1748C (see attachment) After 18 hours, both temp reader dropped about 45C.  Increased TGHT to 440C, IR2C & thermocouple currently read 1912C & 1762C, respectively.   Wednesday, October 07, 2015, 12:28 Lowered TBHT to 200A and TGHT remained at 440A.  IR2C = 1900C, TypeC = 1745C.  Not much affect from TBHT.  Will increase TBHT back to 230A, then start ramping down TGHT and taking temp readings.   Wednesday, October 07, 2015, 17:49 Stepped down TGHT to 160A and TBHT stayed at 230A.  Cooling down temp is generated.  See attachment.  Notice the overall temp during cooling is lower than that during heating.  TGHT and TBHT will be ramped down to 0A.  Chamber will be vented tomorrow.  More details later...

Thursday, October 08, 2015, 12:01  

Test 2: To heat the target container back to ~440A and measure the temperature with the type C thermocouple (inside the tube, away from the centre block) and compared the temp reading with the 2C-IR.   

Chamber is currently being pump down, vac at 9e-6 Torr.  

Will ramp up TGHT to 160A and TBHT to 230A at 2A/min.

 Thursday, October 08, 2015, 17:01

TGHT is now at 440A, TBHT is constant at 230A - IR2C is reading the same as before, 1910C, but Type C is reading lower at 1770C.  (see attachment)

Will keep the current at 440A overnight. 

 Friday, October 09, 2015, 10:06

TGHT has stayed at 440A, TBHT at 230A for ~18hours.  R-temp dropped slightly from 1910C to 1890C and typeC dropped from 1770 to 1756; otherwise the measurements are reproducible. 

After the group discussion, the online heating curve will be re-calculated based on the temp reading from the IR2C curve. 

Next, the target container will be filled with UCx material and the conditioning current for Evap#1 will only go up to 440A (or at least the required current to reach the end of the re-carbonization step). 

So pay attention to the current when heating the target up in EVAP#1.

Initiate cooling at 2A/min for TGHT and 1A/min TBHT

 Friday, October 09, 2015, 11:35

A note about the voltage that may explain the change in the temperature: 

See attachment #2: 

Left plot = Test #1:

Initially TGHT ramped up to 423A and temp measured at 1900C.  Notice, about an hour later, there was a sudden drop in the voltage, and from thereon, the temp was measured at 1860C.  About 18 hours later, TGHT was increased to 440A to achieve 1910C.  

Right plot = Test #2 
Ramped up TGHT to 440A, temp measured 1910C.  At that constant current over the 6 hours period, the voltage slowly increased, and the temperature slightly dropped to 1895C.