<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
<!--
html{color:#555555;}body{line-height:1.5;font-family:'Trebuchet MS','Helvetica Neue',Arial,Helvetica,sans-serif;font-size:87.5%;}h1{font-size:1.6em;}h2.field-label{display:inline-block;font-size:1em;padding-right:5px;min-width:10em;margin:0.3em;}.problem_report{line-height:1.5;max-width:60em;}fieldset.problem_report.resolved
legend{background-image:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVQ4jWP8//8/AyWAiZACd3f3/xYWFrht+f//P1a84t3e/0obff4rbfT5D1GGXR0LuoEr3+/7X3W4n2gvwA0gVSOKAcqbfPGGpImJCU45JgYGBoa7fpsZ22wLSbadgYGBgRE9GrF55Vf2BYbHjx8zYjWB0ljAcAGGExkZ/0MtwuoCggmJEBh4AzBS4pMnT/7fuXOH4dKlSwwnT56EiwcGBv43MDBgMDExYdDX12eQkZGBhAlyiC5YsOA/AwMDUXjLli3/iYoFQgAA+pSxZrXofD0AAAAASUVORK5CYII=);background-repeat:no-repeat;padding-left:18px;}fieldset.problem_report.needs_attention
legend{background-image:url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABmJLR0QA/wD/AP+gvaeTAAAA9ElEQVR42sWTvUoDQRSFv9wMKWxSBVmzdhZJIwTWv9pyLWxTpbE1kBeJPoLxBazzBgGFKNqlHXAhsITUw1y7sMpmjER0YJrDPWcO556BPzhjYPJjlhfT82LUpxcK6Lo5U0JMgcu56tXy7BQajeBDpkAcAEdz1W6uyrLdYieK2DMmKCArcqczpH/ddc0msy+OkyQJC4h3N0ynx+Q5ALtUNs5q5U+8e+R+VPFi4kjk3NZqd++qUK+TZVnYwSfAOyvejeLXt/2qVG/dYoG1dqseBNco27bs/wXKWhIDB8AhcFLAH4Bn4Al4AUqT7RVC++6mv/JVPwDi3VGzomYvyAAAAABJRU5ErkJggg==);background-repeat:no-repeat;padding-left:18px;}.problem_report div.field-items{display:inline-block;}div.date-vitals p{font-size:87.5%;}a{text-decoration:none;}.Readme a:link,.Readme a:visited,.Readme
a:active{color:red;}
-->
</style>
</head>
<body id="mimemail-body" class="elog-logentry-notify">
<div id="center">
<div id="main">
<style>
<!--/*--><![CDATA[/* ><!--*/
div.field-vitals{
margin: 0.5em 0;
}
div.field-vitals .field-type-taxonomy-term-reference {
margin: 0.1em 0;
}
article.comment {
padding-left: 10px;
}
article.comment.odd {
background-color: #EEEEEE;
}
article.comment.even {
background-color: #DDDDDD;
}
div.node-content.logentry table{
width: auto;
border-collapse: collapse;
border-spacing: 0;
border-width: 1px;
}
div.node-content.logentry th{
border: inherit;
}
div.node-content.logentry blockquote{
background-color: #FFFFFF;
}
div.node-content.logentry caption{
font-size: 1em;
font-weight: normal;
}
table.field-vitals{
margin-top: 1em;
margin-bottom: 1em;
font-size: 87.5%;
}
table.field-vitals th{
vertical-align: middle;
text-align: left;
width: 15%;
padding: 0.1em;
}
table.field-vitals td{
vertical-align: middle;
text-align: left;
width: auto;
padding: 0.1em;
}
table.field-vitals td li {
margin-left: 0;
list-style-type: none;
list-style-image: none;
}
table.downtime {
width: 30em;
margin-bottom: 1em;
border: 1px black dotted;
}
table.downtime th {
text-align: center;
}
table.downtime td {
text-align: center;
}
tr.caption th {
border-bottom: none;
}
table.downtime tfoot{
background-color:#EEEEEE;
}
div.field-name-body{
margin: 1em 0;
font-size: 110%;
}
div.date-vitals p{
margin: .1em 0;
}
article div.ctools-collapsible-container{
margin-left: -5px;
clear: both;
}
#comment-form{
margin-left: 5px;
border: graytext outset medium;
-moz-border-radius: 15px;
border-radius: 15px;
padding: 1em;
}
div.comments-form-box {
margin-top: 2em;
margin-bottom: 5em;
}
h3.comment-title {
/* display: none; */
}
p.author-datetime{
font-weight: bold;
}
/*--><!]]>*/
</style><article id="node-1347423" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/4274375" rel="bookmark">Follow-up Re: Follow-up Re: Hall B cryo investigation and changes to allow operation of Hall B magnets</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/4274375/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/4274375/delete?destination=email/send">Delete</a></li></ul></div>
<div class="date-vitals">
<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/4274375" class="lognumber" data-lognumber="4274375">4274375</a>. Submitted by <a href="https://logbooks.jlab.org/user/kashy">kashy</a> on <time datetime="2024-04-05T05:40:41-0400" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1712306441&end_date=1712313641&book=HBLOG&book=HBTORUS&book=CLOG">Fri, 04/05/2024 - 05:40</a></time>. </p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/hblog">HBLOG</a> <a href="https://logbooks.jlab.org/book/hbtorus">HBTORUS</a> <a href="https://logbooks.jlab.org/book/clog">CLOG</a></td></tr><tr><th>References: </th><td><a href="https://logbooks.jlab.org/entry/4273892">4273892 - Follow-up Re: Hall B cryo investigation and changes to allow operation of Hall B magnets</a></td></tr></table></div>
<div class="logentry node-content">
<p>After looking last night, I found that it appears that the preliminary conclusion that the low amount of flow through the 500L Dewar and thus its return U-tube was most if not all of the problem.<br />
While looking I saw a strong correlation between the Dewar valve position (see attached plot for signals EV8210.ORBV ) and the flow to Hall B (CFI6711B) {This shows that flow is a strongly dependent variable and that they are closely coupled in time.)</p>
<p>One can also see that the Dewar return temperature in the DBX T(D8522DR) is oscillating quite a bit. from 8.3K down to 6.3K. this is also correlated but with the Dewar supply valve position but there is a lag and a lot of "overshoot". 2K/8K (25% peak to peak variation)</p>
<p>One can also see that the flow to the Hall is raning from 8.9 to 6.9g/s or varying 22% peak to peak</p>
<p>Finally the Pressure in the Dewar (PI8210) is quite stable (~20mbar/1400) (1.4% peak to peak variation) (or if one wants 20mbar/400 ignoring the atmospheric pressure 5%).</p>
<p>It might be wise and should be possible to stabilize the Hall B system more by switching the input variables on EV8210 (LL8210) and EV8210A (TD8522DR) such that EV8210 controls on TD8522DR and EV8210A controls on LL8210.</p>
<p>I suggest that we have a meeting with Hall B staff this morning to discuss implementation, with folks that are involved with Hall B operation. If anyone else is interested in joining please e-mail <a href="mailto:kashy@jlab.org">kashy@jlab.org</a> and <a href="mailto:pasyuk@jlab.org">pasyuk@jlab.org</a> to be invited. Eugene, please set up that meeting for anytime between 09:00 and 12:00 this morning or let me know if needs to be another day. Thanks</p>
</div>
<div class="attachment-box">
<div class="image-wrapper"><img view_mode="elog_email" class="image-style-plentybig" src="https://logbooks.jlab.org/files/styles/plentybig/public/2024/04/4274375/Dewar Tuning 2.png" width="960" height="549" alt="" /></div> </div>
</article> </div>
</div>
</body>
</html>