10.32

CARME chamber 5.8e-12mbar (see attachment 1)
Backing 1.6e-08mbar (Edwards vacuum cart w/RGA)

CARME temps - see attachment 2

All SAES D2000-10 & UHV1400 NEG power OFF
All SAES D2000-10 ion pump OFF
Gate valve open

11.01

All SAES D2000-10 ion pump ON

#  V/V       presssure/mbar
1  5012/5019  4-8e-11
2  5012      < 8.9e-12
3  5012      < 8.9e-12
4  5012      < 8.9e-12

11.04

CARME chamber 5.7e-12mbar
Backing 1.7e-08mbar (Edwards vacuum cart w/RGA)

12.12

CARME chamber 5.3e-12mbar
Backing 1.7e-08mbar (Edwards vacuum cart w/RGA)

All SAES D2000-10 & UHV1400 NEG power OFF
Gate valve open
All SAES D2000-10 ion pump ON

#  V/V       presssure/mbar
1  5012      < 8.9e-12
2  5012      < 8.9e-12
3  5012      < 8.9e-12
4  5012      < 8.9e-12

All ion pumps now stabilising wrt V/I/pressure

log (pressure) versus time - see attachment 3

16.00

CARME chamber 4.9e-12mbar - see attachment 4
Backing 1.7e-08mbar (Edwards vacuum cart w/RGA)

All SAES D2000-10 & UHV1400 NEG power OFF
Gate valve open
All SAES D2000-10 ion pump ON - see attachment 5

#  V/V       presssure/mbar
1  5012      < 8.9e-12
2  5012      < 8.9e-12
3  5012      < 8.9e-12
4  5012      < 8.9e-12

All ion pumps now stabilising wrt V/I/pressure

CARME temps - see attachment 6

Observing pressure transients from 5e-12mbar to c. 6-7e-12mbar which recover in c. 5-10 minutes 

21.00 CARME chamber 4.7e-12mbar

10:10 Pressure on the chamber = 3.1e-8mbar. RE-72 temperatures are ~120-125C with set limits at 80C. D2000 temperatures are ~370C. D2000's reduced from 60W to 30W and all UHV 1400s reduced to 50W each to cool both the chamber and the D2000s so that ion pumps can be activated. 

10:38 Pressure on the chamber = 1.7e-9mbar. Re-72 temperatures begining to fall and are currently ~117-122C. D2000 temperatures are ~290C.

11:05 Pressure on chamber = 1.1e-9mbar. RE-72 temperatures are ~114-118C. D2000 temperatures ~275C.

11:42 Pressure on chamber = 9e-10mbar. RE-72 temperatures are ~109-113C. D2000 temperatures ~230C. Power in the D2000s reduced to 10W each to speed up cooling. 

13:02 Pressure on chamber = 3e-10mbar. RE-72 temperatures are 100-103C. D2000 temperatures ~200C.  Power in the UHV 1400s reduced to 25W to speed up cooling. Total heating power is now 325W from the UHV1400s and 40W from the D2000s.

14:11 Temperature plot attached.

15:40 Pressure on chamber = 1.2e-10mbar. RE-72 temperatures are ~80-84C with the heaters starting to control temperature of the bakeout. D2000s temperatures are ~150C. I will leave things as they are to let temperatures reach equillibrium overnight. 

27 October

08:00 Temperature stable. See attached.

08:30 Pressure on chamber = 1.2e-10mbar. D2000s temperatures are 150C, have turned them off to cool to below 80C

09:35 Pressure on chamber 1.18e-10mbar. D2000s temperatures are 110C. Bakeout set point reduced to 0C and neg elements switched off. Ion pumps set up and will be activated when D2000 temperatures are below 80C.

Settings on the ion pump have been left to default, except for the ramp rate which has been reduced to 1s from 10s as we are only flashing pumps for a short period of time, and the conversion factor which is set to 150A/torr for D2000 pumps. 

10:50 Pressure on the chamber = 7.53e-11mbar. D2000 temperatures at 80C. Gate valve was closed leading to an increase in pressure up to the high -9 / low -8 mbar range. Conclusion at the time was that the UHV1400s were still too hot and thus outgassing at such a rate that caused the large pressure increase. Once the valve was opened again, the pressure dropped to the mid -11 range again. Gate valve has been found to have been installed upside down, this may also contribute to the pressure increase. Due to low pressure on the backing line and neg pumps cooling which will increase pumping power we may not have to close the valve to reach the -12 mbar range however. 

After speaking with Keith, valve being installed upside down shouldn't pose any significant difference to obtainable pressure, however would be good to install properly at next chance. 

11:45 Pressure on the chamber = 5.55e-11mbar. D2000s temparatures are 75C. Ion pumps activated for first flash of 30s pumping. 

11:55 Pressure on the chamber =5.44e-11mbar. Ion pumps flashed for the second time. Pressure given inside 3 ion pumps reached the minimum of 8.9e-12mbar, 4th pump registered 1.3e-10mbar. 

13:24 Pressure on the chamber = 4.02e-11mbar. Ion pumps flashed for the third time. Pressure inside ion pumps was the same as last flash. 

15:40 Pressure on chamber = 2.88e-11mbar

Find attached plot of pressure (mbar) against time for the pump down from 10:11 on 27/10/20. It looks like negs may have cooled enough to begin pumping nearer the end of the day where the rate of pumping speed appears to increase.

Thu 22 October

22:15 Temperatures stables, slowly decreasing.
Bump - rising front corresponds to heaters turned on. Falling front to D2000 turned off?
See attached.

Fri 23 October
09:57 Temperatures stable. See attached.
13:09 Temperatures remain stable. No significant changes.

Sat 24 October
21:27 Temperatures stable. See attached.

Sun 25 October
*Daylight saving is in effect. Time on the Raspberry Pi is no longer incorrect*
07:57 Temperatures stable. See attached.
19:05 Temperatues mostly stable. See attached. Will leave overnight and move setpoint to 80 C early tomorrow morning

Mon 26 October
07:37 Temperatures mostly stable. See attached. Setpoint to 80 C.

10.40

CARME chamber 2.84e-08mbar
Backing 1.2e-7mbar (Edwards vacuum cart w/RGA)

CARME temps - see attachment 1
vessel 146.62 deg C max diff 21.42 deg C
octagon 27.85 deg C max diff 6.35

SAES HV power modules - see attachments 2-12

14.00

CARME chamber 2.78e-08mbar

Start 4x SAES D2000-10 *NEG* pumps (ion pump OFF) - see attachments 13-18

Ramp 45 mins
Hold 60 mins
225W/550deg C

NEG pumps report temps c. 130 deg C

14.15 ramp

CARME chamber 2.0e-07mbar
Backing 3.3e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 230-250 deg C

14.30 ramp

CARME chamber 2.34e-07mbar
Backing 4.1e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 330-350 deg C

14.45 ramp

CARME chamber 4.02e-07mbar
Backing 4.1e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 450-455 deg C

15.00 hold

CARME chamber 4.56e-07mbar
Backing 5.7e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 500-505 deg C
output c. 50V, c. 3A, c. 150W

15.20 hold

CARME chamber 4.40e-07mbar
Backing 5.1e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 530-540 deg C
output c. 160-170W

15.40 hold

CARME chamber 3.46e-07mbar
Backing 4.3e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 540-545 deg C
output c. 160-170W

15.50 cycle complete

Ramp 45 mins
Hold inf mins
set output 60W

re-start CARME bakeout
set point +120 deg C

15.55 ramp

CARME chamber 5.15e-08mbar
Backing 1.4e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 350-360 deg C

16.15 ramp

CARME chamber 4.53e-08mbar
Backing 1.5e-07mbar (Edwards vacuum cart w/RGA)
NEG pump temps c. 260-270 deg C

16.17 CARME chamber temperatures - attachment 20

Neg and Neg-Ion pumps have been connected up to the control modules. Controller on the right is connected to the D-2000s. Middle controller is connected to the wall section negs (1x2negs in series and 1x3negs in series) and the moving detector negs (2x2 negs in series). Left controller is connected to the intermediate section negs (2x2 negs in series). Must connect IN/OUT interface on the back of the controller or the alarm for an open circuit is triggered. When no thermocouple is connected Tmax must be set to zero otherwise the thermocouple alarm is triggered.

13:00 Pressure on chamber= 6e-9mbar

13:55 I have begun ramping up the middle controller. Ramp time is 45 minutes, slightly longer than the recommended 15-30 mins in the manual to see how well vaccum reacts.  Controller will hold maximum power for one hour for activation. Controller has 4 outputs, one for each neg cable. Outputs 1-3 are the 2 negs in series, output 4 is the 3 negs in series. Parameters for outputs 1-3 are; Vmax=100V, Imax=5A, Pmax= 400W. Parameters for output 4 are; Vmax=110V, Imax=5A, Pmax=600W. 

14:05 Pressure chamber = 1.92e-6mbar. Power per output is 60, 78, 79, 87 W. 

14:15 Pressure chamber = 2.4e-6mbar. Power per output is 114, 148, 150, 168 W.

14:25 Pressure chamber = 1.44e-6mbar. Power per output is 201, 261, 264, 300W.

14:35 Pressure chamber =  1.12e-6mbar. Power per output is 305, 398, 397, 466W

14:56 Pressure chamber = 1.52e-6mbar. Negs are on max power and are holding for an hour.

15:45 Intial activation completed. Negs have been set to half power to maintain temperature at ~200-250C. Parameters set for outputs 1-3; Vmax= 50V, Imax=5A, Pmax=200W. Parameters set for output 4; Vmax=70V, Imax=5A, Pmax=300W. Pressure on the chamber is now 4.4e-8mbar. The pressure tomorrow morning should tell us if the activation has been successful, afterwhich I will activate the next lot of negs. Average vessel temperature is now 146C. I believe our 'internal thermocouple' isn't reading the internal temp after all and is just the temperature of the bottom feedthrough flange, as its temp maxed out at 175C and followed a similar gradient to the other vessel thermocouples.  See attached temperature plot.

20 October

08:30 Pressure on the vessel = 2e-8mbar. Pressure hasn't dropped significantly probably due to negs maintaining a temperature of 200-250C causing significant outgassing. Chamber temperature has maintained at 145C so outgassing from chamber will also have increased also. 

08:45 2nd set of negs activated. Intermediate chamber negs activated (2x 2 negs in series) which are connected to outputs 3+4 on the left controller. Parameters for outputs; Vmax=100V, Imax=5A, Pmax=400W, Rise time= 30mins, Hold = 60mins. 

First set of negs remains at half power. 

Pressure on the vessel =8e-8mbar

08:55 Pressure on vessel = 1e-6mbar. Outputs; V=74, 74W I=2.2, 2.2A P=79, 79W

09:05 Pressure on vessel = 2.2e-7mbar. Outputs; V=58,58V I=3,3A P=175,175W

09:10 Pressure on vessel = 3e-7mbar. Outputs are; V=79,79V I=3.7A P=300,300W.

09:20 Pressure on vessel = 1.2e-6mbar. Outputs are; V=100V, I=4A, P=400W. Negs are now on hold for the hour activation. Chamber temperatures are stable at ~145C still

10:45 Negs are being held at half power to maintain temperature. All that is left is the D2000's on Thursday. Pressure in the vessel is staying constant at ~8e-8mbar. Chamber temperatures ae stable at ~145C. 

12 October 

10:00 Bakeout temperatures stable. Pressure on the backing line is 3e-7mbar which is the lowest we have achieved on the backing line so far. Vessel pressure can't be measured at the moment as temperature exceeds the max operational temperature of 80C. 

14 October

11:30 Bakeout temperatures stable. Slight day/night cycle can be seen and a ~2-3C dip over the weekend, probably due to heating in ETC turning off at night and over the weekend. Vessel average remains ~130C. Pressure in the backing line dropped to 2.5e-7mbar. EU plug Adapters have been delivered, waiting on leads to begin activation of NEG pumps.  

5 OCTOBER

08:21 Temperatures stable overnight. See attached. Baking continues.
Remember to visually inspect the tent for potential new drafts the next time in Daresbury.
Also remember to check on thermocouple 1-4 status / position.

10:15 Draft caused by section of top blanket collapsing slightly producing a hole at the top-back end of the volume. Only way to remove draft is to power down and shift 
some of the larger blanket sections over to support the collapsed bit. Keith requires temperatures >120C for the vessel average to proceed so heat was powered down and 
jacket reconstructed. See attached photos of the top of the baking volume (Sorry for quality).

Pressure on vessel when baking concluded: 2e-7mbar

13:00 Baking jacket all sorted, temperature set to 60C to equilibrate. New session had to be started as cooling then heating confuses the rates on the baking program. All 
looks good at the moment, will continue to monitor and increase temperature when needed. Automatic mode may be able to be utilised again as rectifying the insulation on 
the 
back has reduced the thermal gradients somewhat. 

Pressure on vessel when baking restarted: 1e-8 mbar
Bumax order has also been delivered

16:00 Monitoring remotely, bakeout has been on automatic for an hour and is currently at 67C. Vessel gradient ~7.5C

17:15 All looks okay, will leave for a few hours now. Temp is 73C, gradient ~8.2C

22:00 Automatic baking to 90C gradient >10C. Ramped to 105C for RE72-1 and 100C for RE72-2. Will leave overnight to stabilise

6 October

9:50 Temperatures stable, increasing to 115C, 105C 

11:20 Temperatures stable, Increasing to 120C, 115C

13:15 Temperatures stable, increasing to 125C, 120C. Vessel average ~115C. 

14:45 Temperatures stable (see attached). Increasing to 130C, 125C. Vessel average~120C

20:16 Temperatures stable, may be getting to edge of how hot we can get. Increasing to 135C, 130C overnight. Vessel average~128C should be sufficient.

7 October

07:30 Temperatures stable, have reached max temperature we can achieve 132C, 128C on RE-72 thermocouples. Vessel average~131C should be sufficient. Temperatures will be 
maintained until Monday when negs can be activated. 

20:30 Temperatures stable (see attached)

8 October

10:30 Temperatures stable

9 October 

8:30 Temoeratures remain stable 

(NOTE: Raspberry Pi internal clock appears to be on GMT, rather than GMT+1 due to daylight saving.)

Baking started on Mon 28 Sep. Due to WiFi connection authorisation expiring, no remote access was possible until
Tue 28 afternoon.

JM found remotely that temperature had increase up to 80 C, and baking had then been shut off due to negative
gradients. Unclear what happened. System was already cooling.

Restarted baking in automatic mode. Baking shut down automatically after few hours. It is likely the automatic
mode was being confused by vessel cooling and being heated at the same time. 

29 SEP

20:30 Switched to manual mode (60 C). Left overnight

---

30 SEPTEMBER

08:10 Temperatures seem stable, but slight temperature gradient across vessel would prevent automatic mode from
working. See attached.
Unclear why RE72-1 let temperature reach 64 C when setpoint is 60 C. May be affected by RE72-2. Not worrying,
but may confuse automatic mode.
Ramped up to 70 C manually.

11:10 Temperatures stable. Ramped to 80 C manually. Gradient in CARME vessel unchanged at ~11 C. See attached.

14:18 Found baking had stopped shortly after last check. One floating thermocouple reported temperatures above 300 C. 
Unclear what happened. Possible fault? See attached. 
Restarted baking manually at 40 C. Waiting for temperature to stablise. Vessel still cooling - cannot activate
automatic mode.

15:00 Temperatures OK. Ramped manually to 50C

18:10 Temperatures stable. Ramped manually to 60 C. Left automatic mode on

20:20 Found temperature setpoint at 66 C. See attached.
Huge spikes in thermocouple 1-4 Floating (side-low). Same thermocouple that reported temperature spikes earlier. May be
faulty or touching heater directly. Seems to happen for T=65 C and above.
Set to manual mode. Temperature setpoint 60 C. Left overnight.
Will ask local people to remove thermocouple 4 from picologger 1 (aka #A0067/395, port 4) to continue.

---

1 OCTOBER

08:00 Temperatures stable. Interesting behaviour of problematic thermocouple 1-4. Trend looks real. Seems to confirm
hypothesis it is touching a heater.
Waiting for DL locals to disconnect it.

09:49 Thermocouple 1-4 disconnected. Increased temperature manually to 75 C / 70 C. 
It appears RE72-1 consistently reports 5C above its set point. It controls 3 heaters vs. 8 heaters controlled by RE72-2. 
This is most likely due to RE72-2 needing greater power output to reach its setpoint, increasing RE72-1 thermocouple
temperature as a result. 
RE72-2 may be doing very little at the moment.
Hopefully placing its setpoint 5 C above will force both heaters to work together. This may decrease temperature
gradients observed in the vessel.

16:20 Increased temperature manually in steps up to 95 / 80 C.
The uneven temperature setpoints associated with the two RE72 appears to have reduced the temperature gradient in the vessel.
Will ramp up to 100 later this evening and leave overnight.
See attached.

22:00 Temperature stable. Rates are showing unphysical rates (too high / too low) and occasionally going all to zero at the
same time. 
Looks like a previously observed bug that I thought had been sorted. Will have to debug again. Does not affect manual mode.
Ramped temperature to 105 / 95 C. Leaving overnight.
See attached.

---

2 OCTOBER

07:58 Temperatures stable. See attached. Slight gradient in CARME vessel (~11 C). Not worrying.
Ramped manually to 115 / 105 C

12:16 Temperatures stable. See attached. Valve temperature at 46 C.
Ramped manually to 125 / 115 C

17:34 Temperatures stable. See attached. We seem to be getting close to the upper limit of what the tent can achieve.
Ramped manually to 135 / 125 C
Will leave overnight.

---

3 OCTOBER

08:32 We have been baking at full power (heaters always on). Temperatures stable. 
Appears to be as high as we can go with this tent configuration.
Will leave in manual mode and monitor throughout the day.
See attached.

17:00 Temperatures stable. No changes from this morning.

21:00 Temperatures stable. See attached. Baking continues overnight.

---

4 OCTOBER

07:30 Found temperatures decreased overnight by around 10 C. See attached. 
We are still baking at full power. Room temperature has not changed.
Most likely explanation is part of the tent giving / moving due to the baking and a draft being developed.
Will keep monitoring during the day.

13:50 Temperatures stable, no changes from last check.

20:22 Temperatures stable. See attached. Leaving overnight.

I have (fingers crossed) got the baking stepping up nicely now. I have used some of the outer shell to act as a shield and to direct airflow towards the front and back of the baking volume. I also moved the RE-72 thermocouples to a higher temperature region and replaced the broken thermocouples. The program is on automatic mode and has currently stepped up to 40C with the max diff reduced to ~4C.

I will continue monitoring for a bit but all looks good at the moment. 

Additionally, our baking exploits over the weekend got us down to 9e-9 mbar when I came in this morning.

Sat 26 Sep

09:15 Baking started automatic mode

13:30 Baking continues, heating is slower than expected due to high chamber bottom temperatures

00:00 Baking stopped. Temperatures won't increase due to high temperature of the bottom of the chamber producing thermal gradients that are too high. I believe this is due to heaters being closer to the chamber as tray sits higher up than in previous test (see heaters.png). A shield above the heaters, similar to those we utilised in early tests in Edinburgh, may help to disperse the heat more evenly around the baking volume and not directly at the bottom of the chamber. I can improvise a shield similar to those using pieces of the aluminium outer layer of the baking setup I have spare on Monday and restart baking. This will also allow me to replace the two damaged thermocouples

Sun 27 Sep

11:50 Baking restarted. Manually set temperature to 50 C. Started automatic mode for additional safety checks. Will check again / increase temperature manually in a few hours

13:45 Found baking had stopped due to automatic mode detecting negative temperature gradient in TC7 Floating (bottom). See plot attached. Restarted baking at 50 C in manual mode

17:30 Found temperatures had stabilised. Increased temperature to 60 C. Issues seems to be that bottom thermocouples run hotter than the reference thermocouples of the RE72. The temperature the RE72 are set to maintain is not the temperature of the chamber. This is the cause of the strong gradients. Swapping the position of the thermocouples may be sufficient. Thermocouples presumed faulty on Friday may be working OK - could just be positioned in hot spot immediately above heaters.

18:00 Baking off to allow cooling down overnight.

10:00   Vessel P = 3.99e-8 mbar,  RGA P = 1.4e-6 mbar 

10:54   Vessel P = 3.89e-8 mbar,  RGA P = 1.4e-6 mbar

Vessel continues to pump down. Baking Jacket fully installed and testing of baking begins before leaving on automatic mode for the week. Some baking jacket pieces may need to be re-jigged a little for use in GSI with the interaction chamber but will be fine for this bakeout. Note that due to the valves 'being in the way' the front of the baking volume holds the majority of the heaters

During this testing phase I have noticed the vessel pressure increase slightly even with vessel temperatures of approx 30C. Pvessel = 5.66e-8 mbar currently. 

Automatic mode started 14:06. I will monitor to check everything is okay before letting it run over the weekend 

16:00 I have noticed that two of the thermocouples floating(back) and floating(top) may be damaged as they were giving sharp spikes in temperature. I have just removed these thermocouples so they should just read the picologger temp. The jacket looks like it is holding temperature quite well. I have set the temperature to 35C and am currently waiting for temperatures to equillibriate before putting back into automatic mode. Pvessel = 1.68e-7 mbar

19:00 Temperatures look good, I will begin bakeout tomorrow morning now, so if anything goes wrong its not in the middle of the night. Have a good weekend all!

Following overnight pumping by Leybold turbo pump

09.12 6.26e-8mbar, 2.8e-6mbar (RGA station), leak rate 5e-12 mbar.l/s

09:52 6.08e-8mbar, 2.8e-6mbar (RGA station), leak rate 8e-12 mbar.l/s

10.10 6.02e-8mbar, 2.8e-6mbar (RGA station), leak rate 8.5e-12mbar.l/s 
KM says leak cart currently isolated CARME chamber + RGA cart - no He
has been used around chamber this week so figure represents noise.

10.36 5.94e-8mbar, 2.8e-6mbar (RGA station), leak rate 4.7e-12 mbar.l/s

10.40 KM isolated RGA station (@RGA station) from CARME chamber to replace current RGA (FC sensor) with a more sensitive RGA (with multiplier + FC sensor) 

CARME vacuum pressure (with no backing) will rise somewhat during this process

11.17 1.35e-7mbar

11.20 New RGA install complete, backing line opened, CARME pressure recovers in < 10s to 5.83e-8mbar

14.08 5.59e-8mbar, 2.7e-6mbar (RGA station), leak cart disconnected (by KM)

Cables for neg and neg ion pumps connected with cables trailed out of the octagon through back and front of the octagon. Neg-ion pump connectors are labelled with Kapton 
tape to prevent confusion with neg connectors. Baking jacket has been partially constructed and will be completed tomorrow. 

Connected Leybold Ionivac IE514 to Leybold Combivac CM52 Vacuum Gauge Controller

Rear panel - power ON

POST checks OK

Change parameters by

select PARA

select <-> to display Sen

select PARA to display S-on

select <-> to display HAnd

select PARA and hold for 7s

select CH to select CH3

select -> hold for 2s 

With CARME gate valve closed for c. 24h CARME chamber pressure is 6.43e-5mbar @ 13.34, 6.52e-5mbar @ 14.15


15.45 CARME Leybold turbo restarted

16.06 1.58e-6mbar, 3.5e-5mbar (RGA station), leak rate 3.6e-10 mbar.l/s

16.27 9.44e-7mbar, 3.3e-5mbar (RGA station), leak rate 3.6e-10 mbar.l/s

16.39 7.67e-7mbar

17.00 5.85e-7mbar, 2.5e-5mbar (RGA station), leak rate 2.60e-10 mbar.l/s

17.20 4.83-7mbar, 2.3e-5mbar (RGA station), leak rate 2.17e-10 mbar.l/s

Baking octagon moved into position along with the bottom insulation and heaters
 

Turbo-pump Issue approximately 13:00 22/9/20.

While moving the baking octagon into position, the power connector became disconnected from the turbo pump. The pump controller provided the warnings of connector failure and high pump load (probably due to it reading the frequency of the pump as 0 Hz when disconnected and thinking this was due to a high pump load). I believe the valve then was slightly knocked causing a vibration in the turbo, which couldn't be corrected for by the controller as it had become disconnected. The result of this was the turbo noise growing louder (similar to the turbo in the edinburgh lab when venting). At the time I didn't know the connector had become disconnected, as it was still attached to the turbo, and due to the warning messages on the controller, noise of the turbo and lack of information on what had happend, I decided to close the valve connecting the chamber to the turbo and vent the backing line up to the turbo and in order to remove and replace the turbo. 

The chamber was in the high -6 mbar range when the valve was closed. The turbo was replaced with the second turbo which began pumping again (with the power connector properly secured this time) on 23/9/20. The turbo doesn't show any obvious sign of damage, the blades in it are free to spin with no hindrance, but we will have to get it tested by the vac lab to be sure. 

Cooling of baking volume finished over the weekend, attached are some plots of the bakeout test. Bakeout2.png is the thermocouple profile for the entire period over the week. The heating in the first seven hours followed a nice linear rise of ~5C/hour, in the 7-40 hour period the heating rate slowed due to an issue with our octagon average limiting the increase in the temperature. The period from 40-65 hours was due to the picologger heating up to unacceptbly high temperatures which paused the heating. The octagon average and picologger problems were solved after this, with hours 65-75 showing the linear increase seen previously of ~5C/hour until the maximum temperature of the was reached. The maximum of the RE-72 controllers was 135C with the chamber average ~140C. The next 48 hours the bakeout was left to maintain its temperature, with slight day/night variations observed. During this period both heaters were on in order to maintain the temperature as can be seen in RE72_test2.png, where 1 represents the heater on and 0 the heater off (note for RE72 1 I have shifted these values to 1.5 and 0.5 respectively to better show on the same plot). The rest of the bakeout time shows the cooling of the volume in a serious of 10C and 5C steps. 

Graphs for the cooling profiles of each step (5C and 10C) are attached. Keeping the chamber temperature gradient below 10C is most dependent upon the top and bottom temperatures of the chamber. The bottom of the chamber cools much faster than the top of the chamber, down to a minimum value before the heaters kick back in once the RE72 temperatures arrive at the set point. An equillibrium time is then required for the top of the chamber to cool before the next step can be implemented. The 5C steps are recommened for future cooling due to chamber gradients not exceeding the 10C limit and the shorter 'equillibrium time'. Top/Bottom_test2.png shows the difference in chamber and air temperatures between the top and bottom of the baking volume, with a large difference in the air temperature between top and bottom potentially having a significant effect on the cooling of the chamber. I hope improved insulation on the main chamber will result in less heat losses from the bottom of the baking volume and a smaller cooling gradient for the bottom of the chamber during the step down. 

I have deconstructed the baking jacket on the chamber and am ready to begin moving the jacket over to the other chamber. 

Pressure on the leak cart is 7.1e-7 mbar as of 09:44. 

10:28
Reducing temperature in steps. System cooling down. See attached.

Pressure on the leak cart: 1.6e-6 mbar

The Chamber has continued to pump overnight and we have reached a pressure of 3.3e-6 mbar as of 10:15. Power cable for the hot cathode gauge was found. Gauge did not give a reading so pin connections were checked, all is okay so it may be thepressure is still too high within the chamber, gauge was thus turned off. I have attached the RGA from this morning which has increased accuracy so has been cleared up for most of the noise from yesterday. I have begun removing the covers for the neg-ion pumps, attached is the how it looks without the cover. The covers have strong magnets in them so I will put in a box far away from our electronics.

10:15    3.3e-6 mbar (cart)

11:27    3.2e-6 mbar (cart)

13:26    3.2e-6 mbar (cart)

16:00    3.2e-6 mbar (cart)

I have begun manually reducing the temperature for the bakeout, to observe the rate of cooling across the vessel. I have noticed a bug in the program, the rate of each thermocouple reads as if it is increasing despite the decrease in temperature of the thermocouple. The actual temperatures and averages appear to be working okay. 

09:43   RE-72 temperatures are 135 deg. Temperature set to 125 deg.

11:01   RE-72 temperatures are 125 deg. Chamber temps equillibriating, average chamber temperature 125.5 deg and max difference is ~3 deg. Temperature set to 100 deg.

11:14   RE-72 temperatures are 115 deg. Chamber max difference exceeds 10 deg, chamber average is 115 deg. Temperature set to 115 deg will wait to equilllibriate. Recommend not to lower temperature by >10 deg. Top of the chamber cools much slower than the bottom. 

13:26   RE-72 temperatures are 115 deg. Chamber average is 115.3 deg, chamber max difference is 2.8 deg. Temperature set to 105 deg.

14:20 Previously unobserved bug occured - all temperature display frozen. Rates still OK. Temperature control still OK. Rebooted Baking.x remotely. Back OK. Reduced temperature to 90 C. See attached temperature plot before rebooting.

18:00 Temperature reduced to 80 deg.

21:25 Temperature reduced to 75 deg.

A pump cart and leak cart have been connected to the chamber via the top turbo at the back of the chamber. An air line has also been connected to the valve to open/close it. The pirani gaige has also been replaced by a blank flange, a gauge on the pump cart can measure the pressure in its range. The turbo fan and controller were set up and pumping was started after lunch. 

While pumping, the hot cathode gauge was connected to its controller and bakeable shell installed. Gauge will be turned on if pressure is sufficiently low tomorrow, currently no gauges are 'active' on the chamber with the only gauges on the pump cart. 

An RGA is attached to the pump cart and can be seen in attached photos. Majority of contribution in RGA is water with significant contributions from gases in air (nitrogen, oxygen etc) as expected during early pumping. RGA is also quite noisy. 

The leak rate observed is below the minimum value the leak cart can detect (<1e-12 mbar*l/s). Helium was sprayed around the chamber and on the wire seals, however no change in the leak rate was observed, so no significant leaks!

The turbo has been left to pump overnight with the pressure 2e-5 mbar at 16:15. Attached is the pressure against time from 15:00 till 16:15, the rate of pumping in this period was 0.68e-5 mbar/hour. 

16 September

08:50
Baking continues OK. Temperatures stable, did not increase with respect to yesterday evening.
See attached.

15:00
Baking continues OK.
See attached.

20:22
Baking continues OK.
See attached.

17 September

08:20
Baking continues OK. Temperatures slightly decreasing?
See attached.

Tuesday 15 September

08:40
Rates started working again. Unclear what yesterday evening's bug was caused by. Will investigate eventually.
Temperature setpoint reach T=150 , however even at full power (heating constantly on) the RE72 appear unable to
reach past T = 135
See attached.

Perhaps better insulation would be required. 
However, this temperature is sufficient to bake CARME with the detectors inserted.


Day shift
Baking continues and will be left overnight to gather more data. Vessel temperatures are increasing by roughly 1.5 deg/hour with the vessel average temperature now 141.5 
deg.

Wire seals fully closed and tightened. Bolts were tightened first finger tight, then to 50 N.m and finally to 80 N.m in a pattern so that seal is closed evenly. Leak and 
pump cart are ready to be connected to the turbo for leak testing tomorrow. 


19:20
Baking continues OK. Temperatures seem to increase slowly. See attached.