sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hello, Carl, Piyush et. al.,

I have been wondering where Piyush's 2.7 A/s quench threshold comes from, which I haven't found.  ( Please show me if you can. )  

I've just looked again at our BaBar disk server (\\bnl.gov\c-adnas\babar),

in this memo "Historical Memos & Emails/1998/ 5-12-1998.pdf"
which is part of the whole big documentation under : "Volume 5 DESIGN AND QUALITY CONTROL REPORT/5.1 GENERAL AND MAIN COMPONENTS"
(~p. 20 onwards),

it gives the Final Testing at SLAC, and the results/plots there have been mentioned and re-used in BaBar Magnet paper a few times.

Let me use the page numbers in  "Historical Memos & Emails/1998/ 5-12-1998.pdf".

On p.9, near the bottom half, we saw the 2.573 H (due to 2.573 V at 1A/s), the inductance which made me think that the test was with all the return yoke on.
On the same page, at the top paragraph, it mentioned 1.3 mOhm (for resistance of the power supply line).

On p.10, the last paragraph says:
=======================================================================
"Due to a temporary limitation on power supply voltage (10V), this test was not done during
commissioning. However, during the tests discussed before, the solenoid was charged at rates up to 3.3
A/s. At 1.7 A/s the coil temperature increases about 0.1 K due to current in the external cylinder. At 2.7
A/s the temperature rise is about 0.2 K. Operation of the coil is not dependant on ramp rates as high as
3.3 A/s."
==============================================================================

So, they've tried at 3.3 A/s  ....

On p. 12, at the 2nd last line, they mentioned 1.38 mOhm for the power leads.

In the letter here :   https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Shared%20Documents/BaBar%20Documents/The%20BaBar%20Detector%20Superconducting%20Magnet%20and%20Power%20Supply.docx  ,

Martin Berndt said "about 1.25 mOhm".    

So, I guess the power lead resistance is around 1.3-ish mOhm .   {  This determines the time scale for slow discharge/ramp-off using
just the cable resistance (and freewheeling diode), as I have started to learn from Carl and Piyush ....... }

Kin