sPHENIX discussion of the superconducting solenoid

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

Hi,

 

To look at the bright side (as Dave Phillips taught me), Carl and Pablo did another short-circuit and manage to ramp using J. Morris’

new function in the Pet page (using the PSI… interface) to ~4682 A as the plot that I attach shows.   The 6/5 factor mistake has

been corrected in the data acquisition.   But Winston hasn’t put in Carl’s newest constants/offsets such that the two curves are slightly

different.  Carl told me that they should be the same as both are from power supply actually, not really as what the labels imply. 

 

 

Even I noticed solid ice developed at the top of the Current Leads.  Paul Orfin today reduced the “lead flow” and the ice melt.  Unfortunately,

the melting liquid drops down, across the G10.  This screwed up our intention to do hipot.  By drying up the moisture/condensation at the

G10, you could see reduced current to ground.   The highest we went was like 183 V which tripped the hipot power supply at 1 mA.  So, we decided

to wait until the melting ends … Paul was hoping for a thermal equilibrium at some point that there won’t be condensation dropping down …

 

 

In the JPG file, you can see that the temperatures of the coils are around 55 K now.  Though it doesn’t drop as fast as yesterday, it probably still

reaches 10-15 K by Tuesday such that the Cryo group can do the last stage of operation to go to ~4.5 K.

 

 

On another note, we’ve had an interesting and successful external cryo review (recommended in the last Director’s Review).  You may view

the indico page for more details :

https://indico.bnl.gov/conferenceDisplay.py?confId=4079

 

or you may grab the presentation from here :

 

https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Past%20Presentations/2018-1-12%20External%20Cryo%20Review.pptx

 

 

 

Kin

 

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