(jim nic)

We've implemented the ISI CPS -> MICH feedforward (MICH freeze). It was a fairly simple process:

We installed the feedforward coefficients that Ryan suggests in his writeup. These could be re-measured to potentially improve the subtraction.

Then we compared the spectrum of the feedfoward signal and the MICH control signal. We saw a relative gain of 188, so this was added to a filter bank in the feedforward path.

We added a 50Hz low pass to the feedforward path so we aren't injecting too much noise.

When the feedforward path is enabled, we have a reduction in the MICH control signal RMS by a factor of 2-3. See attached figure (reference traces are with FF turned off).

The CPS has a 9Hz feature. Jim says it's from HEPI. This is injected into the MICH control signal, but the change to the RMS is insignificant.

Also attached is the settings of the MEDM screens. Several of these are 'hidden' because they have only been autogenerated and not added to the main screens.

Finally, the easy way to turn on and off the feedforward is by setting the channel H1:LSC-CPSFF_GAIN to 0 (off) or 1 (on). It has a 10 second ramp.