sPHENIX discussion of the superconducting solenoid

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

Agenda and powerpoint/PDF files can be found at : https://indico.bnl.gov/conferenceDisplay.py?confId=2763

 

 

1.      Holger Witte showed us his force calculations during a quench by “Comsol”.  The PDF file can be found in the above indico page as well as :

https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Past%20Presentations/2017-01-18%20BaBar%20Magnet%20Forces%20in%20Quench.pdf

 

Using the Opera model (.opc) that B. Parker has built, H. Witte converted it to a step file and took it as the input to “Comsol”.  He has used a BH curve that he’s always used (p.4), which has less carbon content than 1010 steel, more magnetic than 1010 => a worse case than the 1010 steel (the majority of our steel may be 1010).

 

The forces shown there in the PDF are (always) the total forces due to the Eddy Current as well as from the static magnetic field.  To save himself a little time, he did the case of current going up instead of coming down; but it should be the same as in a quench (but just in the opposite direction).

 

In the pages 8-10, he showed the total forces during quench when the entire steel are connected without gap.  But in reality, there may be some gaps

between the steel which would reduce the eddy current.   In pages 12-14, he showed the forces if he added a 2 mm gap, and the forces as a result

are close to the static cases (when there is no quench).

 

By comparing the plots on p. 8-10 to p.12-14, the force strengths are actually less with full eddy current (if all return yoke are connected together)

than the force strengths with reduced eddy current or in the static case.  ( I guess, this has something to do what Lenz’s Law says, eddy current creates magnetic field that opposes the magnetic field that created it. )   Therefore, the obvious conclusion is that it’s not

 

 

2.      I mentioned that P. Rosas took the tech. (from I. Marneris) to do BLIP work instead of working sPHENIX’s power supply.  He’ll get back to sPHENIX after RHIC cool-down.  C. Schultheiss has started to work on sPHENIX data-acquisition system ...

3.      J. Mills told us that the machine supervisor in Florida State U. last week asked for detailed assembly drawing.  J. Hock and R. Ruggiero have been working to provide them.   They should be sent out tonight.  J. Mills hopes that after this, that machine supervisor will be able to provide a date when they can deliver at least the bottom 4 Brackets/Jack Support, in a week.   Let’s see …

4.      I showed that we needed to change the Microsoft Project because the WBS structures have been changed from  task-nature-oriented (Design, Fabrication, Installation … and each of these have “Mechanical”, “Cryo”, “Power-Supply” and “Magnetic-Measurement” components)
to Deliverable-oriented (ie. each of “Mechanical”, “Cryo”, “Power-Supply” and “Magnetic-Measurement” has their Design/Fabrication/Installation). 

5.      J. Mills suggested that we should discuss again whether/when we’ll want to do a test for the Magnet in 1008, before or after the installation of all detectors.  ( Doing the test before the installation will delay the installation schedule. )

 

 

 

Kin