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Entry  Mon Apr 29 19:23:49 2019, Jon, Update, Computer Scripts / Programs, Scripted tests of suspension VMons using fast system 
    Reply  Thu May 2 10:41:50 2019, gautam, Update, SUS, SOS Magnet polarity 
Message ID: 14587     Entry time: Thu May 2 10:41:50 2019     In reply to: 14585
Author: gautam 
Type: Update 
Category: SUS 
Subject: SOS Magnet polarity 

A concern was raised about the two ETMs and ITMX having the opposite response (relative to the other 7 SOS optics) in the OSEM PDmon channel in response to a given polarity of PIT/YAW offset being applied to the coils. Jon has factored into account all the digital gains in the actuation part of the CDS system in making this conclusion. I raised the possibility of the OSEM coil winding direction being opposite on the 15 OSEMs of the ETMs and ITMX, but I think it is more likely that the magnets are just glued on opposite to what they are "supposed" to be. See Attachment #6 of this elog (you'll have to rotate the photo either in your head or in your viewer) and note that it is opposite to what is specified in the assembly procedure, page 8. The net magnetic quadrupole moment is still 0, but the direction of actuation in response to current in the coil in a given direction would be opposite. I can't find magnet polarities for all the 10 SOS optics, but this hypothesis fits all the evidence so far..

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