[Hallb-engineering] [Revised Logentry] Follow-up Re: Follow-up Re: Hall B 4K cryoshutdown

[kashy at jlab.org]

Logentry Text:
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The Warm up is going well. 

The Torus average coil temperature is now up to 53.5K and warming at 2.5K/day. All coils and ALL 12 hex beams are all within 2K  of this average temperature which shows that the shields and MLI were installed nicely and are working well. The peak vacuum pressure at the chimney during the warm up was 0.0186torr at the chimney on TC8103, while TC8100 (at the upper turbo only got to 0.002torr, and TC8102 at the lower pump went to 0.0146torr. Interestingly the peak pressure at the lower turbo occured 40 minutes after the peak at the chimney.

The Soldenoid average coil temperature is now 40K and warming at 5K/day. Since the Solenoid shield is cooled by liquid helium boiloff the shield is only acting as another layer of MLI so its warm up rate expected to be higher than the Torus at this point. The peak vacuum pressure in the Solenoid was 0.0004 torr 

The Buffer dewar now has 41.6% indicated helium level

We are pumping on many of the U-tube vacuum spaces, especially the long one on the solenoid.

Hall B will likely want to start circulating 80K helium mid to late week. 

At present there is plenty of recovery compressor for Halls A, B and C to use 4 atm helium either to warm their magnets (Hall A) or to keep their magnets at 80K ( Halls B and C) . For operators who need to use this flow contact Chris Perry and also keep an eye on the Position of CPV10DR if it goes closed and CPV0840BY goes closed then the Purifiers are overloaded. Also watch the contamination sensor CCT10N21A which is presently running at ~9ppm



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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3574866
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