sPHENIX discussion of the superconducting solenoid

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

Hi,

It's not the vacuum group.  The C-AD group is in charge of the magnet vacuum .  Vacuum was of course on during magnet mapping in Nov.

Chintan (Cryo engineer) told me that late last year, after the mapping, when we found some problem with a valve / leak, the Cryo group took out a pipe in Jan. 2023 or so and cleaned it.

It was at that time that the pump was stopped.  ( Everything was sealed in principle. ) We didn't notice until now 😅

Kin

-------- Original message --------

From: "Sondheim, Walter E" <sondheim AT lanl.gov>

Date: 4/17/23 1:38 PM (GMT-05:00)

To: "Yip, Kin" <kinyip AT bnl.gov>

Cc: "Sondheim, Walter E" <sondheim AT lanl.gov>

Subject: RE: Hipot problem went away after we started pumping again ... Please keep the Cryo pump on.

Hi Kin that is great news! Do you know why the vacuum group removed the pump in the first place? I am assuming it was in place and running during the magnet mapping period in 1008.

Thanks,

Walter

 

From: sPHENIX-magnet-l <sphenix-magnet-l-bounces AT lists.bnl.gov> On Behalf Of Yip, Kin
Sent: Monday, April 17, 2023 10:55 AM
To: sphenix-magnet-l AT lists.bnl.gov
Cc: Albanese, Marianna <malbanese AT bnl.gov>; rolandg AT mit.edu; Stefan Bathe <stefan.bathe AT baruch.cuny.edu>; Michnoff, Robert J <michnoff AT bnl.gov>; Morrison, David <morrison AT bnl.gov>; Kobasiuk, Frederick D <kobasiuk AT bnl.gov>; O'Connor, Eric <eoconnor1 AT bnl.gov>; Karl, Robert F <rkarl AT bnl.gov>
Subject: [EXTERNAL] [Sphenix-magnet-l] Hipot problem went away after we started pumping again ... Please keep the Cryo pump on.

 

Hi,

 

This morning, we disconnected the braids, then we hipoted on the 1008B side (water-cooled buses and dump resistor).

And "surprinsgly" (at that time at least), the hipot went successfully at 520 V (and we stayed at least for a minute).

 

Then, we went to the top platform of 1008-IR and we did a hipot.  Surely enough, it failed after it was higher

than 420 V or so.  This indicated something wrong on the magnet side (that we couldn't believe it !).

 

We tried again to move apart the heater cable (connected to the Gas-cooled/Current Leads) etc.  And we did hipot again slowly and the highest we went was ~460V.  And then we started talking with the Cryo group

(Roberto).  Originally, the dialogue was about those heater cable but soon, we asked about the Vacuum

situation.  Roberto saw 1 gauge at E-1 leavel and another at E-5 ... but the vacuum pump has not been running for some time. 

 

Soon, the Cryo group staff came and started the pumping when we just tried to disconnect two voltage tap

cables on the platform just to make sure (which we didn't think but just to make sure).  Just after a couple

minutes' pumping, we went to 505 V --- the highest that we have gone this week ! 

 

So, we put back the voltage tap cables and we waited for half an hour.  Voila, after that, we went to 520 V

without any problem.    I attach a picture of success at 520 V !   ( You  don't know how happy we were

when we reached this value ... after >10 failures this week. )

 

So, we'd like to ask the Cryo group to keep the pump working from now on.

 

Kin