[Target] Magnet seems to have decreased current autonomously by 0.5 A. We manually drove it back to 121.825 A.

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User name J. Shields

Log entry time 20:25:44 on March 9,2012

Entry number 365126

Followups:

365128 03/09/12 20:31 J. Shields [Target] Noticed that the warm return flow (FL91115) suddenly went off scale high (> 200) just before the magnet acted up
365191 03/10/12 01:03 M. Yurov [target] Magnet current has decreased (same as Entry number 365126/365189)

keyword=[Target] Magnet seems to have decreased current autonomously by 0.5 A. We manually drove it back to 121.825 A.

We discovered that the magnet current was suddenly 0.5 A less than where we last drove it. The power supply presumably ramped the leads up to 121.818 A, went to driven mode, decreased current to 12.326 A, then returned to persistent mode (did not zero the leads), all without user interaction and while beam was on. James says this is some sort of protection mechanism going off at the wrong time. We drove the magnet back to 12.825 A and will be watching it.