sPHENIX discussion of the superconducting solenoid

["Mills, James A" <mills AT bnl.gov>]

Hi,

 

I heard back from Wes concerning the BABAR coil.  Below is his very helpful response.

 

Jim

 

From: Craddock, Wesley W. [mailto:wwc AT slac.stanford.edu]
Sent: Monday, November 20, 2017 1:47 PM
To: Mills, James A
Cc: Haggerty, John; Racine, Mike
Subject: RE: Question about the cryostat support jacks

 

James,

Sorry that I didn’t get to you sooner, but I had four reviews last week.  Unfortunately, I have little solenoid documentation left with me.  However, you will want to make sure that the coil is centered on the iron.  I believe the lower and side jacks can do that for you.  As for the top jacks I would imagine that just barely touching after pump down would be a good thing.  I don’t believe that we ever released the jacks during our BaBar operation.  Several things are very important in turning on the magnet.  First all the tie rods should be released according to the spreadsheet that Mike Racine and I made.  These are by turn of the nut.  Second, just in case the point was missed, the solenoid is only designed for force in the forward direction.  For our iron we offset the cryostat axially by 1 cm.  It is now probably impossible to  use any of the strain gages, but you can monitor coil axial position with current and use the force conversion info that we supplied. 

 

It might be helpful if you could send some photos of the jacks to refresh Mike’s and my memory.

 

Wes

 

From: Mills, James A [mailto:mills AT bnl.gov]
Sent: Friday, November 17, 2017 7:30 AM
To: Craddock, Wesley W.
Cc: Mills, James A
Subject: RE: Question about the cryostat support jacks

 

Hi Wes,

 

Sorry to be a pest, but I was wondering if you have any thoughts in regard to the installation.   Our plan is to start pumping down either today or Monday with the hope of installing the final steel plates for the test, but want to fully engage the jacks before we do this.   What we are planning to do is to seat the jacks once we start pumping down so that any gap that is created from the vacuum load will be taken up by the jacks so that we ensure full engagement of the jacks when we go to full field.  Our plan would then be, once the test is completed, to disengage the top two and two side jacks before we bring the cryostat up to atmosphere.

 

Thanks,

Jim

 

From: Mills, James A
Sent: Thursday, November 16, 2017 4:50 PM
To: Craddock, Wesley W. (wwc AT slac.stanford.edu)
Cc: Mills, James A
Subject: FW: Question about the cryostat support jacks

 

Hi Wes,

 

I was wondering if you remember anything about the installation of the cryostat inside of the steel that could help us with the issue below.

 

Thanks,

Jim

 

From: Mills, James A
Sent: Wednesday, November 15, 2017 11:17 AM
To: 'Racine, Mike'; Craddock, Wesley W.
Cc: Haggerty, John
Subject: RE: Question about the cryostat support jacks

 

Hi Wes,

 

Would you be able to help us with the question I posed below to Mike?  Thank you for any insight you can provide.

 

Best regards,

Jim

 

From: Racine, Mike [mailto:racine AT slac.stanford.edu]
Sent: Wednesday, November 15, 2017 10:53 AM
To: Mills, James A; Craddock, Wesley W.
Cc: Haggerty, John
Subject: Re: Question about the cryostat support jacks

 

HI Jim,

I do remember you from the laast time you were here. glad to see progress is being made on the solenoid install and tests. I was not part of the install crew for the solenoid into the steel, I was working on all the liquefier piping at the time.

I would think that you might want to make contact at the sides first before making contact at the top.

I've cc'd Wes Craddock on this to see if he has any input on this.

 

good to hear from you.

 

Mike

---

From: Mills, James A <mills AT bnl.gov>
Sent: Wednesday, November 15, 2017 7:43:05 AM
To: Racine, Mike
Cc: Mills, James A; Haggerty, John
Subject: Question about the cryostat support jacks

 

Hi Mike,

 

I don’t know if you remember me, but I was with John Haggerty a few years ago when we shipped the BABAR coil to Brookhaven.  I hope you are doing well.  I am sorry to bother you, but I have a question that I was wondering if you could help us with.

 

We have been slowly working on testing the magnet since it arrived at Brookhaven, first testing the cryogenics and then performing a low field (100 amp) test of the coil.  We are now in the process of getting ready for a high field (full current) test of the magnet.  I have included a photo to show you the coil as it sits inside a temporary flux return that we have built.

 

We have aligned the cryostat to the steel (supporting the coil on the four bottom jacks) and now want to engage the remaining 8 (4 mid plane and 4 on the top) of the wedge jacks that hold the cryostat in place with respect to the steel.  You can see the six jack set located at the near end in the photo.  And as I said the coil is resting on the bottom four (2 at each end) with the remaining jacks essentially running free from the cryostat.  However, before we snug up the remaining jacks we are wondering if we need to preload the jacks (top and sides) after they make contact with the cryostat’s outer cylinder.  We are thinking that we should push the top jacks in towards the center of the cryostat until they just make contact with the outer cylinder (on the welded landing pads) and then push in another 2.5 to 5 thousandths of an inch (2.5-5 mils).  Then snug up the side jacks (mid plane jacks) to a point where they then contact the cryostat. 

 

But before we actually do this we were wondering and discussing if, when you guys installed the cryostat inside of the BABAR steel, you did the same thing (pushing the jacks in some nominal distance after first making contact with the cryostat) to ensure that the jacks all make contact with the cryostat outer cylinder?  Do you remember what you guys did when you installed it?  Did you simply snug up the jacks so that they all made contact?

 

Thanks Mike for your help with this.

 

Best regards,

Jim