ELOG CARME

AIDA GELINA BRIKEN nToF CRIB ISOLDE CIRCE nTOFCapture DESPEC DTAS EDI_PSA 179Ta CARME StellarModelling DCF K40

CARME

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Mon Oct 26 10:35:05 2020

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10:10 Pressure on the chamber = 3.1e-8mbar. RE-72 temperatures are ~120-125C with set limits at 80C.&nbsp;D2000 temperatures are ~370C. D2000&#39;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.&nbsp;

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.&nbsp;D2000 temperatures ~230C. Power in the D2000s reduced to 10W each to speed up cooling.&nbsp;

13:02 Pressure on chamber = 3e-10mbar. RE-72 temperatures are 100-103C. D2000 temperatures ~200C.&nbsp; 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.&nbsp;

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.&nbsp;

10:50 Pressure on the chamber = 7.53e-11mbar. D2000 temperatures at&nbsp;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.&nbsp;

After speaking with Keith, valve being installed upside down shouldn&#39;t pose any significant difference to obtainable pressure, however would be good to install properly at next chance.&nbsp;

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

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.&nbsp;

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.&nbsp;

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&nbsp;negs may have cooled enough to begin pumping nearer the end of the day where the rate of pumping speed appears to increase.

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