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Kind listeners:</div>
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One of the first principles scaling arguments brought to my attention long ago by Leigh Harwood is that, to lowest order, a temperature change in the steel of an iron-dominated magnet will result in expansion (1+a)*L longitudinally by the same fraction as the
inverse pole-tip gap 1/[(1+a)*G] changes. These cancel as they apply as the product (1+a)*L * (1 / [(1+a)*G]), leaving only weaker things like a temperature-dependent permeability in play. So one _expects_ iron temperature to remain a very weak influence.</div>
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I thought you might find this interesting and useful. I hope I have not fouled up the algebraic representation.<br>
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MIchael Tiefenback<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> BTeam <bteam-bounces@jlab.org> on behalf of Jay Benesch <benesch@jlab.org><br>
<b>Sent:</b> Tuesday, September 13, 2022 18:39<br>
<b>To:</b> BTeam <bteam@jlab.org><br>
<b>Subject:</b> [BTeam] Follow-up Re: More data on LCW Temperature variations</font>
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<div class="PlainText"><a href="https://logbooks.jlab.org/entry/4041098" data-auth="NotApplicable">https://logbooks.jlab.org/entry/4041098</a><br>
Submitted by okumar on Tue, 09/13/2022 - 15:56.<br>
<br>
We did more investigation on this issue, so far we are able to verify <br>
that ARC7, ARC9 and RSEP9 shunts voltage fluctuation do coincide with <br>
the beam position change. Plotting all the respect shunt currents with <br>
respect to shunt voltage, LCW temperature & beam positions shows no <br>
shunt current variations (see attached waveforms). Investigation on this <br>
problem will continue tomorrow.<br>
<br>
three figures.<br>
<br>
Let's hope the heat exchanger swap tomorrow solves the problem. <br>
<a href="https://tasklists.jlab.org/atlis/tasks/107471" data-auth="NotApplicable">https://tasklists.jlab.org/atlis/tasks/107471</a><br>
<br>
The coils are not well coupled to the steel, but steel may see some <br>
modest temperature, and therefore thermal expansion/contraction. Pole <br>
length will clearly change. Whether pole spacing will change enough to <br>
compensate is beyond my powers of visualization.<br>
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