[Xrayops] intention to change fill intervals

APS Experiment Hall X-ray Operations Problem List xrayops at mailman.aps.anl.gov
Fri Apr 20 10:29:37 CDT 2012

In the past three days, we've observed a beam instability that occurs about 10 hours after a fill to 100 mA, when the beam has decayed to about 88 mA. The instability manifests as a drop in lifetime (from 70 hours to <10 hours), a jump in emittance of more than 10%, and an increase in coupling to 2~3%. So far, we haven't found a way to suppress the instability, which seems related to vacuum in the S37 area (probably from the relatively new scraper).

The most expedient way to solve this problem is to fill every 8 hours instead of every 12. This will keep us above the current at which the instability occurs.

If there are any issues with this, please contact me ASAP.

--Michael Borland
borland at aps.anl.gov

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