[Esr-users] [New Logentry] Hall B Magnet and Dewar Cooldown

[kashy at jlab.org]

Logentry Text:
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At 9:30 we started taking flow up to 3 g/s of 4.5K 
11:30 both magnets had <6k at the inlets and we upped the flow to a max of 8g/s
The flow is oscillating from 0 to 8g/s with an average of ~6g/s. This is with all the Hall B valves in manual!
We looked back at the previous cooldown of the Torus and it had a similar oscillation. (Date 3/14/2018)
I think this is just the nature of putting Liquid helium into the recooler while the coils are still ~80K. Not much we can do about this except press on and look for alternative solutions. 
>From 13:20 to 14:10 we tried using EV8111BY to see its influence. All it did when using it was to cool the supply into CCM A but no help with the oscillation.
14:20 started working with Chris Perry on tuning of the Supply valve to hall B CEV6711B 
14:50 We got an alarm on PT8670. I thorottled back sligthly on PV8611CD to lower the flow through the solenoid coils. I called Cryo and they said they are processing gas and have increased suction pressure. They will lower the setpoint so as not to back pressure us as much. Chris asked if we can cut back on hall B Flow so they can process more gas so  we are at 6g/s supply to Hall B. PID tuning of EV6711B has helped.
15:30 I setup a PID to maximize the flow through the Solenoid but keep from blowing the magnet reservoir relief valve RV8670. It controls EV8611CD based on reservoir pressure PT8670. It is working well thus far.

At 15:50 Torus coils are at 77.3K and Solenoid is at 78.3K This setup looks stable for over night. I'll check back later.

Thanks for the help Chris, Cryril, Ruben and Probir.

Dave








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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/3581327
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