This morning I was able to epoxy 2 L4Cs under HAM1, as I outlined last night. I was also able to get the transfer functions, get a quick design for a filter and test it. So it works pretty well, but there is still a fair amount of work to do. First attached asds show the improvement I was able to get on HAM1 with this initial ff on vs off, red and green are the new ground L4Cs, pink and blue are the in loop HEPI L4Cs, where pink is the FF off and blue is with the FF on. Between a couple hz and 25 hz I was able to get up to a factor of 10 reduction in the Z motion of the HEPI. Out at 50hz the motion is a little bit worse, but I have some more tuning to do. Should be able to fix that.

Second attached asds compares the HAM1 improvement to some of the other HAM ISIs. Brown is the HAM1 HEPI with FF off, greens is with the FF on. Pink is the HAM2 GS13s and light blue are the HAM7 GS13s. Basically, HAM2 is doing as good HAM1 at 15hz, without additional FF and doing better by factors of 10 or more everywhere else. HAM7 is better than either by ~20 at 15hz, because of in-vac FF L4Cs and its stiffer support structure, which shows up as the peak in light blue at 38hz.

More work to be done, so we won't trying running this full time yet. I will post pics of L4C locations and some filter design data in a bit. I will also try to get some quick on/off data with the interferometer this afternoon. This could affect the HAM1 asc feedforward, so I'll get in touch with Gabriele or Elenna about that.