sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

-------- Forwarded Message -------- Subject: RE: [Sphenix-magnet-l] A draft plan for the sPHENIX Magnet Low Current Test in Bldg. 912 Date: Tue, 14 Apr 2015 10:59:54 -0400 From: Anerella, Michael D <mda AT bnl.gov> To: Muratore, Joseph <muratore AT bnl.gov>, Lambiase, Robert <lambiase AT bnl.gov> CC: Yip, Kin <kinyip AT bnl.gov>, Wanderer, Peter <wanderer AT bnl.gov>, Joshi, Piyush <joshi AT bnl.gov>, Dimaiuta, Sebastian A <sonny AT bnl.gov>, Kovach, Paul E <kovach AT bnl.gov>, Joshi, Piyush <joshi AT bnl.gov>, 'sphenix-magnet-l-bounces AT lists.bnl.gov' <sphenix-magnet-l-bounces AT lists.bnl.gov>, Escallier, John <escallier AT bnl.gov>

Joe, Bob,

 

Probably Bob’s source of information is construction data and therefore more accurate, but the coil drawing 620RM07142 shows the inner layer with 545-548 turns and the outer layer with 540-543 turns (the uncertainty is from my interpretation of the Italian drawing).  The larger number of turns as designed for the inner layer is due to the greater length/number of thin conductors in the ends of the inner layer (to maintain field straightness in the ends).

 

The main reason I mention this is that the coil drawing shows that in addition to the inner to outer layer splice there are also splices in each end of each layer where the conductor changes from thick to thin (five resistive splices total within the coil).  I don’t see any mention of voltage taps at any of these splices but maybe they there are there.  The splices may affect balancing if a warm-cold correlation is assumed? Cause eddy current effects during ramping?

 

The splices are made by TIG welding the aluminum for a length of 1500 mm, and then after a gap of 200 mm, soldering with tin/lead solder for 300 mm on each side of the weld location. I do not find any mention of making direct contact between superconductors for the soldered connections but maybe this is the case.  I also do not see mention of re-insulating the conductor after splicing but surely at least  this was done.  Maybe Pasquale Fabricatorre can shed some light on this.

 

Mike

 

 

 

 

From: Muratore, Joseph
Sent: Monday, April 13, 2015 4:47 PM
To: Lambiase, Robert
Cc: Yip, Kin; Wanderer, Peter; Joshi, Piyush; Dimaiuta, Sebastian A; Anerella, Michael D
Subject: RE: [Sphenix-magnet-l] A draft plan for the sPHENIX Magnet Low Current Test in Bldg. 912

 

Hi Bob –

 

I was aware of the unequal inductances of the inner and outer layers. The electrical checkout at 4.5K includes ramp tests to determine the imbalance and adjust the delta detector so that it will be balanced. This has had been done on a number of the magnets tested here at 902. Part B.7-8 if I remember correctly addresses this.

 

As far as using L(dI/dt) quench detection, we routinely make use of this scheme to make sure we cover the rare possibility of a simultaneous quench in both halves.

 

I will look into the use of the integral as a threshold.

 

Thanks.

 

Joe

 

From: sphenix-magnet-l-bounces AT lists.bnl.gov [mailto:sphenix-magnet-l-bounces AT lists.bnl.gov] On Behalf Of Lambiase, Robert
Sent: Monday, April 13, 2015 4:11 PM
To: Yip, Kin; sphenix-magnet-l AT lists.bnl.gov
Cc: McKeon, William F
Subject: Re: [Sphenix-magnet-l] A draft plan for the sPHENIX Magnet Low Current Test in Bldg. 912

 

Hi Kin,

 

This is a very comprehensive test procedure.  I’d like to add a few details for the quench detection based on a first pass look of the documentation I saw this weekend.

Coil balance – The two halves are not equal.  The inner coil has a smaller aperture and 531 turns, while the outer coil has a larger aperture and 536 turns.  The scaling factor to equalize the ramp voltage of the two halves should be determined.  SLAC spent a bit of time doing this.  We should determine this number. Quench – The dump switch was triggered if there was an instantaneous exceeding delta V of IST (50mV) or an integral (I haven’t seen the time constant yet) of the delta V by INTEG (I need to find out this number) exceeding 8V.  The integrator was set to zero any time the delta V went below INTEG.  Perhaps we should monitor this integral as well as the instantaneous trip vlaue.  As far as I could tell, they didn’t use Ldi/dt in any calculations.

 

Bob

 

From: Kin Yip <kinyip AT bnl.gov>
Date: Monday, April 13, 2015 at 3:36 PM
To: "sphenix-magnet-l AT lists.bnl.gov" <sphenix-magnet-l AT lists.bnl.gov>
Cc: "McKeon, William F" <wmckeon AT bnl.gov>
Subject: [Sphenix-magnet-l] A draft plan for the sPHENIX Magnet Low Current Test in Bldg. 912

 

Hi,

Joe Muratore has just sent me a draft plan for the low current test.  ( Thanks Joe !! )

For convenience, I've just put his plan (in Word document) to the agenda page :
 
https://indico.bnl.gov/conferenceDisplay.py?confId=1105

Please read and you may comment to the mailing list; or otherwise we'll discuss this on Apr. 22, 2015.

Kin