sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Attach the current / magnetic field for today.

 

From: Yip, Kin
Sent: Friday, February 16, 2018 4:03 PM
To: 'sphenix-magnet-l AT lists.bnl.gov' <sphenix-magnet-l AT lists.bnl.gov>
Subject: Gone back to 4830 A ... We're done ?! If anybody objects to our "conclusion", please let us know before next Tuesday.

 

Hi,

 

This morning, we tried to ramp up at 2.5A/s at 1000A step.  When we more or less reach 3000 A, it seemed to quench (due to inner/outer difference blowing up). 

Zeynep and Carl both thought that it’s real.   An hour later, after the cryo recovers, we tried to ramp up at 2A/s.  From 4000 A, when trying to ramp to 4830 A

without stopping at 200 A step (like last Friday), we quenched at 4410 A.   This is the worst fast discharge and helium jumped out at the top.

 

2 hours later, we tried again and since nobody wants to see quenching again, this time, we ramped at 2A/s to 1000A, 2000 A and then at 1.5 A/s to 3000 A, 4000 A

and then at 200 A step, like last Friday,  but at 1.5 A/s to 4830 A.   We stay there for 36 minutes (from the LogView) until the Paul Orfin said that we have only

liquid helium left for slow discharge.

 

We have gone up to 4830 today again.  It looks like that we can’t really try to ramp too fast.    [  We kind of followed the Run Plan for those 2.5 A trials.  ]

Wes Craddock told me (today):

 

" As for magnet ramp rate the number I remember (not totally certain, but is clearly in the log books) is 1.5 A/sec = 50 min to 4600 amp.  However, this was only after we had become very comfortable with the magnet.  If I were in your shoes, I would pick a more conservative 90 minutes and then watch temperatures as I shortened the ramp time. “

 

So, he’s kind of suggesting we should play safe at least in the beginning of experimental operation at ~1 A/s.   I shared the feeling with Carl that if we just dwell

a bit before going up and we probably will be OK.

 

Since we witnessed the fast discharge, we don’t really need to do the fast discharge at 4830 A.    And we prove that we can ramp the magnet

again even after such a violent fast discharge.

 

You may look at my sPHENIX Magnet calendar :

https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Lists/Calendar/calendar.aspx

 

We started testing on Jan. 22, 2018.    I think we’ve achieved all we need to do.    It seems that we have come to an end of this Test.   ( Part of it is that

people need to go to work on RHIC starting … )

 

Paul Orfin won’t warm up today but he’d like to do so as soon as possible.

 

If anybody objects to the conclusion of this High-Field Test and think that we need to try more, please let us know before next Tuesday (Feb. 20, 2018).

 

Kin

 

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