sPHENIX discussion of the superconducting solenoid

[John Haggerty <haggerty AT bnl.gov>]

Here is Pasquale's written answers.  We will meet via Blue Jeans at 9:30 
today.


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-------- Forwarded Message --------
Subject: Re: Questions for Pasquale :-)
Date: Thu, 26 Mar 2015 13:59:32 +0100
From: fabbric <Pasquale.Fabbricatore AT ge.infn.it>
To: Yip, Kin <kinyip AT bnl.gov>
CC: Haggerty, John <haggerty AT bnl.gov>, Mills, James A <mills AT bnl.gov>, 
Than, Yatming (Roberto) <ythan AT bnl.gov>

Kin,

I think I can answer most of your questions, but for some of them I would
need some time.

First of all let's check that you have in hand all the relevant
documentation.
  I am attaching a file with the list of documents, you shold have
grouped in
abou 10 folders.

This morning I was in ASG and I DID NOT find the folders (four years ago
they
were there!!). It is possible that many documents were scanned, but some
time is needed  for checking what is still there.

Coming to your questions:

1) Do you have the Ansaldo CAD drawing 771620BA.DWG (and others) ?

Many drawings exist as CAD file. Only the name looks stange a drawing
7716 exists
with an electrical scheme. Is this really the drawing you were looking for?

2) Do you have the electronic versions of the Lake Shore temperature
sensors calibration from Tallerico ?

No. However you can find all calibration in 2.4

3)  Wiring diagrams showing connector/instrument assignments to the "C"
labeled connectors etc. ?

I need more time.

4) Do we know what readings should we get from the strain gauges (if we
make them work) ?

  Also in this case I need more time. However you should have four leads
for each sensor. At room temperature
the resistance of the strain gauges shall be 350.XX Ohm (XX beacause any
sensor has its own value). The resistance
increases with strain, according a law I Have to check with ASG.

5)  Why is hypot voltage limited to 520V ? And what is the suggested
voltage for impulse testing ?

The value of 520 V should come from the maxium voltage to ground during
a quench (170 V). It seems that
we used 3 times the max voltage to ground. Indeed we should have used
V=2 x 170 +1000 =1340 V.
However looking at the test and controls a pulse voltage up to 1 KV has
been used.


6) During BaBar operation, did they monitor the field and how ?

I do not know exactly. You should ask to Wes Craddock. I think that they
monitored the
mag field in some locations.

7) The coil position was offset just for avoidibng force inversion
during charge/dis-charge.
We were afraid of possible mechanical oscillations during the
dis-charge. This is not strictly
nesessary if there is no yoke asymmetry.

8) The compressing force of 380 MT can be  held by the coil (about 10
MPa compression)

9) The effect of type, size and position of iron tips shall be carefully
evaluated.

10) Without iron tip the radial field at the coil ends increases,
causing an increase of
the axial force. During the factory test (without yoke) we limited the
field to 1/3 of
the nominal field. For this coil it is better not overcome 20 MPa axial
pressure on coil.

Talk you later

Pasquale


  Il 25/03/2015 21:01, Yip, Kin ha scritto:
> Hi Pasquale,
>
> I've missed one very very specific question from our colleague :
>
> 11. The WEKA valve list shows a DN40 valve with a name tag "V4" with an 
> Kv=45, Digital open close actuation. Is this valve that is on the return flow from 
> magnet going into port PS1 of the valvebox separator vessel?
>
> Kin
>
> -----Original Message-----
> From: Yip, Kin
> Sent: Wednesday, March 25, 2015 3:01 PM
> To: Pasquale Fabbricatore
> Cc: Haggerty, John
> Subject: RE: Questions for Pasquale :-)
>
> Hi,
>
> I attach 3 pictures.   In our question 3, when we talk about "C-labeled" 
> connectors, these are what we mean.
>
> Kin
>
> -----Original Message-----
> From: Yip, Kin
> Sent: Wednesday, March 25, 2015 2:57 PM
> To: Pasquale Fabbricatore
> Cc: sphenix-magnet-l AT lists.bnl.gov
> Subject: Questions for Pasquale :-)
>
> Dear Pasquale,
>
> This is Kin Yip, a physicist from Collider-Accelerator Dept. of BNL.  I look 
> forward to talking with you tomorrow.
>
> As promised, here the questions before the meeting (I put the simpler ones at 
> the top and longer one at the bottom):
>
> 1) Do you have the Ansaldo CAD drawing 771620BA.DWG (and others) ?
>
> 2) Do you have the electronic versions of the Lake Shore temperature sensors 
> calibration from Tallerico ?
>
> 3) Wiring diagrams showing connector/instrument assignments to the "C" 
> labeled connectors etc. ?
>
> 4) Do we know what readings should we get from the strain gauges (if we make 
> them work) ?
>
> 5) Why is hypot voltage limited to 520V ?  And what is the suggested voltage 
> for impulse testing ?
>
> 6) During BaBar operation, did they monitor the field and how ?
>
> 7) In the paper by Bell, et al., The BaBAR Superconducting Coil: Design, 
> Construction, Test (Nuclear Physics B, 78, 1999, 559-564), it was stated that 
> the coil inside of the non-symmetric flux return yoke was offset by 
> approximately 30 mm axially, in the forward direction.  At 3800 amps this 
> created an axial force of 8 tons, which in turn stressed the Inconel tie rods 
> (in effect the tie-rods provided the axial restraint to keep the coil from 
> moving).  It appears that this was intentionally done in order to generate an 
> offset axial force that always acted in the same direction which in turn 
> always loaded in tension the tie rods placed at the backside of the 
> coil/cryostat.  It also provided the benefit of preventing any force 
> inversion during coil ramp-up.  Is my interpretation of this correct?  If 
> these forces created by offsetting the coil were done intentionally, do you 
> recommend that sPHENIX create the same condition in our magnet design (in 
> effect offsetting the coil wit
h respect
to the nominal center of the yoke geometry)?
> 7) If this offset axial force exists, the load path (offset force) is 
> directed from the coil/mandrel to the downstream tie-rods and through the 
> tie-rods to the downstream cryostat end flange that the tie-rods are 
> connected to.  And from the end flange back up through the cryostat barrel 
> (inner and outer) to the upstream end flange which in turn connects the 
> cryostat (at the forward end) to the external cryostat axial supports (which 
> now act in compression)?  Is this the correct interpretation of the 
> anticipated load path of this offset force?
>
> 8) Even though there is this net effective offset axial force as described 
> above that is restrained by the tie-rods, the paper states that there is a 
> pair of corresponding internal magnetic axial forces of approximately 380 MT 
> each acting on the forward and backward ends of the coil.  These forces act 
> in opposite directions with their resultant force vectors pointing axially 
> towards the center of the coil.  Does this then create a net effective 380 MT 
> compressive force internal to the coil, which in theory would be restrained 
> by the stiffness/strength of the mandrel from crushing the conductor?  It is 
> presumed that the mandrel has been designed to withstand these large 
> compressive forces.  However, what happens during a quench?  Does this 
> compressive force as well as the nominal 8 ton offset force simply collapse 
> to zero, or are there transient forces that may in fact reverse direction or 
> possibly increase before decreasing to zero?
>
> 9) BNL will be required to perform a high-field test of the coil prior to installation 
> into sPHENIX.  The temporary flux return that will be used incorporates a rectangular 
> geometry that is not symmetrically placed circumferentially with respect to the coil.  
> Also the pole tips (end caps) placement will be 14" off the face of the cryostat.  
> In the detector design for the experiment (final design) the pole tip locations will be 
> approximately 45" off the face of the cryostat end flanges.  Will the rectangular 
> flux return geometry or pole tip locations create internal forces on the coil that 
> cannot be supported or restrained by the mandrel without overstressing the mandrel or 
> cause the mandrel/coil composite to buckle?
>
> 10) There has also been a request by BNL management to consider running the 
> sPHENIX detector without pole tips in order to reduce the overall cost of the 
> detector.  Can the coil run in a configuration without a pair of pole tips?
>
> See you tomorrow !
>
> Kin


--
Dr. Pasquale Fabbricatore
INFN Sezione di Genova
via Dodecaneso 33, 16146 Genova Italy
Direct tel  + 39 010 3536340
Laboratory  + 39 010 3536437
Secret.fax  + 39 010 313358
E-mail   pasquale.fabbricatore AT ge.infn.it
WEB page  http://www.ge.infn.it/~fabbric/



--
John Haggerty
email: haggerty AT bnl.gov
cell: 631 741 3358

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