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[Sphenix-magnet-l] no change in L at 100% current or 50% or 10%

From: Kin Yip <kinyip AT bnl.gov>
To: "sphenix-magnet-l AT lists.bnl.gov" <sphenix-magnet-l AT lists.bnl.gov>
Cc: "Witte, Holger" <hwitte AT bnl.gov>
Subject: [Sphenix-magnet-l] no change in L at 100% current or 50% or 10%
Date: Mon, 3 Apr 2017 18:01:07 -0400

Hi Carl,

To convince myself, I've just tried to verify using Opera (simulation).   I've computed the inductance (through Energy = 1/2 * L*I^2 ) using Opera.
I've used the full-field test model (originally from Meng but we flattened a small piece of the roof steel) at full current (4596 A), and then 50% of that
and 10% of that.   Opera may take some time (~ hours at full-current) to run each time in fido and at the end, I find its Energy
(which takes the post-processor another 5 minutes or so) which gives => Inductance.

Current (4596 A）                Inductance (H)

100%                                      2.3606
50%                                        2.3609
10%                                        2.3609

[ The computational error could be bigger than the last digit :-) ]

So, this confirms what I have said, ie. there is really no real change in H (when you ramp up). Whatever the saturation at the tiny corners of the steel are negligible.

Kin

[Sphenix-magnet-l] no change in L at 100% current or 50% or 10%, Kin Yip, 04/03/2017