sPHENIX discussion of the superconducting solenoid

["Yip, Kin" <kinyip AT bnl.gov>]

Hello,

My shift today went well so far and John Haggerty will take over at 4 pm.  Eric Mannel will help us again this midnight - Wed. morning.  

After yesterday's discovery of RF interference due to walkie-talkie, today's discovery is Booster pulsing cycle, by just sitting in the sPHENIX Control Room and observing the sPHENIX Magnet Power-Supply Current and voltage tap voltages.

As the picture attached, I have noticed the unusual oscillations of the Power-supply current or the voltage taps (of +/- gas-cooled-leads).  One picture is attached and another one can be seen in your Elog:

https://elog.pbn.bnl.gov:8181/elogs/showfullimage.jsp?URL="FY2022_11_636a92bd000f49f8_tmpPrintElog.gifQaFLP1.gif

 

At first, I didn't know what these were/are and asked around.  Carl Schultheiss suggested that it seemed to be due to Booster pulsing.

I made a few phone calls including Paul Sampson and noticed that Booster is doing power supply testing this week (Mon-Wed.) : https://www.cadops.bnl.gov/AGS/Accel/Maintenance/Schedules/This_week.htm#dsched

The oscillations disappeared for a while and when I saw them come back, I called Paul Sampson (and indeed they just restarted pulsing in Booster) ... and I was able to persuade Paul Sampson to do a little quick experiment with me.   ( I made use of a bit of my C-AD relationship in all these ... )

When he switched off the fast/proton cycles of Booster (though the slow/NSRL cycles were still on), I saw that the oscillations go away.  Then, when he switched on the fast/proton Booster cycles, the oscillations re-appeared ! 

Haha... so sPHENIX Magnet Power Supply is not just sensitive to two-way radio but it's also sensitive to Booster pulsing 🙂  

Kin

---

From: Yip, Kin <kinyip AT bnl.gov>
Sent: Monday, November 7, 2022 3:42 PM
To: sphenix-magnet-l AT lists.bnl.gov <sphenix-magnet-l AT lists.bnl.gov>
Cc: Michnoff, Robert J <michnoff AT bnl.gov>; Albanese, Marianna <malbanese AT bnl.gov>; Mannel, Eric <mannel AT bnl.gov>
Subject: Mapping again ... 20 A power-supply current jump (walkie-talkie !) ... Pablo requests 1-2 days test after the mapping

 

Hi,

After the LOTO/pole-tip door business, we started ramping at 8:15 am and we reached the top about 10:03 am.   The mapper started taking data at 10:09 am for the 44-hour run.    I put quite some information in our C-AD Elog ( https://elog.pbn.bnl.gov:8181/elogs/entryList.jsp?DATABY=shift&ELOG=sPhenix&PAGE=1&DIR=backward&AUTO=yes&MODE=ALL#1669362 ) --- inside C-AD firewall of course.

There are typically fluctuations in the currents, slightly more for the power-supply current than the magnet current.

But around 1:39 pm, I saw a ~20 A jump in the power-supply current and luckily it went away quickly (a few seconds) and only caused ~1 A jump

in magnet current, and no noticeable damage was done.   ( You may remember that we saw a rise of ~400 A for 85 s on Oct. 26 which eventually tripped the Power-Supply and therefore Magnet due to crowbar over-temperature. )  I attach the plot for the current rises and the gas-cooled-leads (voltage taps) actually also saw the jump as well.

I emailed with Pablo/Carl.  A few minutes later when I called Pablo, we discussed and apparently at that time, a CAS person was using radio/walkie-talkie in 1008B mezzanine --- close to our Power Supply.  Pablo said that he'd seen this before and the strong RF signal can trigger disturbance like this.   I was told that we actually have a sign in 1008B (probably on 1^st floor) to tell people not to use radio.  ( I'm going to take a look later ... ) 

And by the way, for things like this (Pablo wants to see whether radio signal on 1^st floor would affect the Power Supply), Pablo requests a 1-2 day test after the mapping.   We can ramp down the Magnet to take out CERN equipment if necessary and ramp the magnet back up.  Pablo's test can be done easily as long as we do keep the Cryo at He temperature.  We have to remember not to warm up immediately after the mapping is done. 

John Haggerty is taking over after 4 pm ... Eric Mannel will do the "00:00 to 08:00" shift.

Kin

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