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Entry  Wed Dec 20 00:43:58 2017, Kevin, Summary, General, DAC noise contribution to squeezing noise budget 40m_squeezing.pdf40mDAC_squeezing.pdf
    Reply  Thu Dec 21 19:25:48 2017, Kevin, Summary, General, DAC noise contribution to squeezing noise budget 40mDAC_squeezing.pdf
       Reply  Fri Dec 22 09:40:19 2017, rana, Summary, General, DAC noise contribution to squeezing noise budget 
Message ID: 13491     Entry time: Fri Dec 22 09:40:19 2017     In reply to: 13490
Author: rana 
Type: Summary 
Category: General 
Subject: DAC noise contribution to squeezing noise budget 
  1. Should not count the ITMs. On those we can use big resistors / filters to cut out the noise.
  2. For the initial LIGO, we used 7 K resistors and the mass was 10 kg. But...the output driver went +/- 150 V.

So we had a max F/m = (20 mA * 0.064 N/A)/(10 kg) = 0.0001. For the 40m, to get the same thing, we would need 40x less current (~0.5 mA). At the moment we have (12 V / 400 Ohm) = 30 mA.

We need to get a spectrum and times series of the required coil current for acquiring and holding the DRMI, and also the single arm. Then we can see where to make noise reductions to allow this drastic force reduction. 

Coil Driver Upgrade wiki here.

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