sPHENIX discussion of the superconducting solenoid

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

Hi,

 

I talked with Roberto this morning (Sun.) and he thought that it’d be too chaotic for the Cryo group to do the RHIC

warmup at the same time as trying to provide 4.5 K Monday morning for the sPHENIX Magnet.    

 

So, we’ll try to do “hipot test” and other necessary electrical tests on Monday.   ( The sPHENIX Magnet

had gone to <~4.5 K once for an hour or so on Sat. as the email below described. )

 

The Cryo plans to set the sPHENIX Magnet to 4.5 K again on Tuesday at 10 am which should last about 7 hours

(also explained in the last email).    Piyush will come back on Tuesday anyway and moving to Tuesday might not

be too terrible J

 

Kin

 

From: Yip, Kin
Sent: Saturday, March 19, 2016 6:16 PM
To: sphenix-magnet-l AT lists.bnl.gov
Subject: probably only 7 hours each time at 4.5 K

 

Hi,

 

Thanks to Roberto’s and the Cryo group’s test this afternoon, you may read the powerpoint

attached with 3 pictures and probably more revealing are his emails below .    In the 2^nd page

of the powerpoint, you may see the situation when Roberto & Co. got the system to ~4.5 K.   

 

Apparently, they can only keep the system at ~4.5K for 7 hours a day.   Then, we need to re-liquefy

and refill … I’m asking Roberto how much time this may take.   ( It may be like an ERL operation. )

 

Kin

 

From: Than, Yatming (Roberto)
Sent: Saturday, March 19, 2016 5:29 PM
To: Yip, Kin <kinyip AT bnl.gov>
Cc: Orfin, Paul <porfin AT bnl.gov>
Subject: RE: about there ... ~5-6-7 K

 

 

Kin,

We just finished the test using the subcooler.

I tried putting the solenoid return to the 9K return of the plant, from the 25K return, but pressure drop was too high and almost lifted the relief of the VTF. Our return shares the same return as the VTF. so we had the VTF at 19.7 psia.

 

So supplied the solenoid with the return to the 25K return of the plant.

 

Consumption rate was 7%/hr.

We used 15% for initial cooldown.

So starting from 80% drawing to 10%, we have 7 hours of 4.5K time.

The level probe we will hav trouble reading stable.

Roberto

 

 

 

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From: Yip, Kin
Sent: Saturday, March 19, 2016 12:46 PM
To: Than, Yatming (Roberto)
Cc: Orfin, Paul
Subject: RE: about there ... ~5-6-7 K

Hi,

 

How much “(low-field) test time” are we talking about ?   Days or hours ?   If it’s hours, I guess we need to coordinate very exactly (so as not to waste) …

 

Kin

 

From: Than, Yatming (Roberto)
Sent: Saturday, March 19, 2016 12:42 PM
To: Yip, Kin <kinyip AT bnl.gov>
Cc: Orfin, Paul <porfin AT bnl.gov>
Subject: RE: about there ... ~5-6-7 K

 

Kin,

 

From yesterday afternoon test, I tried running direct from storage dewar feed.

But the pressure differential was not enough to get the flow, so I will use subcooler.

Not as efficient, so I will go through my storage dewar inventory quicker.

 

Also when I put it on the cold end of the plant, the heat leak is too large,  so we the test time will be dictated by storage dewar inventory.

 

 

I will test the subcooler this afternoon/

 

Roberto

 

 

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From: sphenix-magnet-l-bounces AT lists.bnl.gov [sphenix-magnet-l-bounces AT lists.bnl.gov] on behalf of Yip, Kin [kinyip AT bnl.gov]
Sent: Friday, March 18, 2016 5:12 PM
To: sphenix-magnet-l AT lists.bnl.gov
Subject: [Sphenix-magnet-l] about there ... ~5-6-7 K

Hi,

 

From the temperature change and my conversations with the Cryo group, I can see that late last night (9:30 pm or so), they’ve started to use 10+ K He

gas to cool the system back to <15 K or so.   This afternoon (around 2 pm-ish), they started to use the ~4 K He to cool.

 

Now, the outlet temperature is fluctuating around 7 K and whereas various thermometers in the magnet were showing around ~5 K or ~6 K.

Hopefully, soon it’ll be close to 4-5 K …. I understand that they’ll let the coils soaked in the bath of ~4.5 K He so that hopefully the temperature

deep inside the metallic coil will be all ~ 4.5K.   Sunday or so, they’ll open the valves for the “phase separator” and then there will be a circulating

loop (of liquid He) between the phase-separator and the magnet coil.   This is my rough/probably inaccurate understanding of what it’s going on

and what it’s going to happen.   Thanks for taking the risk to read up to here, hahaha …… J

 

Kin