AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
DESPEC
DTAS
EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
CARME
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Entry time:
Mon Sep 21 09:51:57 2020
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<p>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. </p> <p>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. </p> <p>I have deconstructed the baking jacket on the chamber and am ready to begin moving the jacket over to the other chamber. </p> <p>Pressure on the leak cart is 7.1e-7 mbar as of 09:44. </p>
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