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Hi Don,</div>
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We are currently testing the heater at 92W, while controlling the temperature to 250C. I took a picture between tests, see attachment. So far the heater components look fine after a few days of testing. The current test will probably go for a week or so. We
will have a look at it after that.<br>
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I'm scheduling a meeting for Monday talk about design changes to the prototype. Stay tuned.</div>
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Regards,</div>
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Marc<span style="vertical-align: bottom;"><img style="max-width: 100%;" class="w-1334 h-1000" size="244225" contenttype="image/jpeg" id="imageSelected0" data-outlook-trace="F:1|T:1" src="cid:5f0bb5ed-b94d-4772-9e00-b6348877858b"></span><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Donald Jones <jonesdc@jlab.org><br>
<b>Sent:</b> Friday, February 24, 2023 11:30 AM<br>
<b>To:</b> Marc Mcmullen <mcmullen@jlab.org>; Bogdan Wojtsekhowski <bogdanw@jlab.org>; shahinya@jlab.org <shahinya@jlab.org>; Mark Jones <jones@jlab.org><br>
<b>Subject:</b> heating test setup taken apart</font>
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Hi Folks,</div>
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I turned off the heater test prototype and after it cooled down I took the front off. Things looked to be in fairly good shape initially, but upon examination I noticed some delamination of the heater pads. At least 1 RTD had fallen off. All the pads are very
brittle and easily snap when pulled. </div>
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I don't think that this should be surprising given that I wasn't monitoring the heater temperature which is rated only to 250 degC. Even the crystal temperature at one point exceeded this temperature for some time before I caught it (see plot). However, in
retrospect, I suspect the damage may have been done during the initial heat up stage when I briefly (a couple of hours) turned the heaters up to 140 VAC (see plot). During this time the oven temperature that I was monitoring was well below 200 degC, but the
heater pads may have been much hotter. In fact, during this time I noticed some small wafts of smoke coming from the oven apertures and I didn't know what it was but suspected the aluminum tape adhesive that is rated to 160degC. When I turned the voltage down
to 126 VAC the wafts seemed to reduce which I now leads me to believe that the heaters themselves may have been driven well beyond their rated temperatures. It will be interesting to observe the longevity of these same pads when they are kept below their rated
250 degC by careful monitoring as they will be in Marc's system.</div>
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The system will not be able to run again until the heater pads are replaced. </div>
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On a positive note, the heater tape looks pristine. You wouldn't know it had been baked at 250 degC.</div>
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I have attached some pictures.</div>
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-Don</div>
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<img class="x_ContentPasted0 x_w-1676 x_h-1168" id="x_imageSelected0" width="480" height="335" size="502403" style="max-width:100%; width:480px; height:335px" data-outlook-trace="F:2|T:2" src="cid:06f7fb1c-db69-4f0e-9ed2-c9f12ab9a581"><br>
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Donald Jones</div>
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Hall A/C Staff Scientist</div>
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Jefferson Lab</div>
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