KAGRA Logbook

Reports 1-1 of 1

MIF (ITF Control)

tomotada.akutsu - 4:01 Tuesday 11 February 2020 (12876)

It works! MICH feed forward.

Nakano, Enomoto, T. Yamamoto, Takano, Yokozawa, Akutsu

After 12875, we input the zpk parameters into the corresponding filter bank for MICH feed forward, and it worked very well!! Someone would take nice photos.

To implement the real digital filter, we needed not only the zpk parameters of the filter from MICH to DARM, but also DARM to test mass mirror, as we would like to subtract noise by actually actuating the test mass mirror. The transfer function

From: VIS-ITMX_ISCINF_L_EXC
To LSC-DARM_IN1_DQ

was already measured by Kozakai-san on around Feb 4, and we believed that this part of the transfer function would not vary so much since then, and just used it to do fitting to obtain required zpk parameters for foton. We also added low-pass and high-pass filters to limit the feed forwarding bandwidth within the coherent frequency range. I modofied the LPF and HPF so that the pass freqency rage would not have improper ripples within the pass band.

Comments to this report:

masayuki.nakano - 6:38 Tuesday 11 February 2020 (12878)

Wooohooo! 230kpc!!

The mid frequencies (around 100 Hz) improved by the MICH FF. The HF improved by the higher laser power on REFL PD.

Images attached to this comment

shinji.miyoki - 6:50 Tuesday 11 February 2020 (12879)

Excellent !!

osamu.miyakawa - 7:03 Tuesday 11 February 2020 (12881)

Gooood! Only 4 times more.

takaaki.yokozawa - 7:48 Tuesday 11 February 2020 (12883)

Main constraint at 100-300Hz may come from the PRCL (and MICH??) control noise.

Images attached to this comment

tomotada.akutsu - 9:05 Tuesday 11 February 2020 (12885)

I see; the next is PRCL FF? And it seems the MICF FF filter might have some room to be improved.

By the way, why don't we bring the purple curve named MICH control noise in the sensitivity budget to the correspoinding location??

takashi.uchiyama - 10:15 Tuesday 11 February 2020 (12886)

Good work!!!!!