[Halld-controls] Solenoid sub-coil inductances and the Danfysik quench detector

[Elliott Wolin]

Hi,

Calculated sub-coil inductances at 1500 A from Floyd for the 2-1-3-4 
coil configuration are (subsequent columns are for each sub-coil):

coil 2 (total 4.15 H):    1.3260    0.6130    1.0042    1.2102   
coil 1 (total 7.20 H):    1.4104    1.3824    0.5593    0.3664    
1.0887    1.1580    1.2331   
coil 3 (total 4.12 H):    1.6821    1.0953    0.6768    0.6624   
coil 4 (total 9.61 H):    1.2362    8.3721

Total all coils:  25.1 H

We need fairly good balances to get the quench detector to work well.  
Also, it is supposedly possible to balance non-adjacent sections of the 
coils, e.g. one should be able to balance coil 2 against coil 3, even 
though coil 1 sits between them.  Note that the Danfysik QD has 4 channels.

Considering entire coils, the only balance that works is coil 2 vs coil 
3.  The others are too different.

Thus to get additional good balances we'd have to add sub-coils together 
and not respect full coil boundaries.  I don't think this is a problem.  
But we do want to ensure that every sub-coil is included in a balance 
somewhere...if not a quench in that sub-coil would not be directly 
noticed (although we'd see other problems, and the quench would likely 
propagate to adjacent sub-coils).

So now we have a bit of a Chinese puzzle working out good balances and 
not skipping any sub-coils.  I assume QD channels can deal with 
overlapping measurements...Fernando, is this correct?  I.e. I assume 
that if e.g. sub-coil 1F is used in one QD channel, it can be used again 
in another.  Or will this introduce some sort of problematic cross-talk?

Now to work out good balances...

Comments?

-- 

				Sincerely,
					Elliott
 

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 Those raised in a morally relative or neutral environment will hold
		    no truths to be self-evident.
				   

Elliott Wolin
Staff Physicist, Jefferson Lab
12000 Jefferson Ave
Suite 8 MS 12A1
Newport News, VA 23606
757-269-7365

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