Scraps of text for incorporation in the VIS Meeting Minutes

KAGRA/Subgroups/VIS/MeetingNAOJ

Type-B

Albums

Week of the 18th of January

This week was devoted to the Beam Splitter suspension

Type-B

Albums

Week of the 11th of January

BS: klog 15729

SR3

We moved the SR3 small rack inside of the clean booth to a new permanent position.See this the location in this picture and this other one.

Plan for next week

Type-B

Albums

Week of the 4th of January

SR3

BS

Type-B all

We checked the flanges we could use for the cables of a thermistor. See details in klog 15700.

Type-B

Albums

Week of the 14th of December

Week of the 21st of December

Type-B

Albums

Week of the 7th of December

Type-B

Week of the 30th of November

General

BS

SRM, SR3 and SR2

A TO DO list for SR suspensions.

Type-B

Week of the 23rd of November 2020

[Hirata, Washimi, Satou, Aso, Fabian]

SRM

SR3

Type-B

[Hirata-san, Washmi-san and Satou-san, Ikeda-san, Fabian]

General

SR3

SRM trouble mechanical troubleshooting

Netx two weeks plan

Notes for SRM Klog on 19-11-2020

Assessment of BF and IM

Conclusion

Conditions

Description of experiments

  1. The BF keystone is at 288 um and the IM-V at 321 um.
    • The BF transfer function looks very good (picture 1p1).
    • The IM-V transfer function looks also good (picture 1p2). The vertical OSEMs don't seem to be out of range although they might be close to their limit. I need to check.
    • The IM-Y transfer function also looks good (picture 1p3).
    • When it swings free there is no large oscillation (picture 1p4).
  2. BF keystone down to 172 um (-2000 cnt of actuation).
    • A large oscillation appears: 8 um-pp at 30 mHz. See 2p2.
    • The BF transfer function looks very good (picture 2p3).The resonant frequency is at 273 mHz.
    • The IM-V transfer function looks also good (picture 2p4).
  3. I moved the BF keystone down to 132 um with -2800 cnt of actuation. IM-V goes down to 185 um.
    • BF oscillates with an amplitude of 9 um-pp at about 30 mHz, but IM-V does not move! See picture 3p1.
    • Then I applied a sinusoidal actuation with an amplitude of 2000 counts at 100 mHz. See picture 3p2, 3p3. I removed the AC actuation and measured transfer functions.
    • IM-Y and IM-L transfer functions looks fine. See 3p4, 3p5.
    • IM-P looks good. See 3p6.
    • IM-R looks good although noisy at high frequencies. See 3p7.
    • IM-V looks really bad. See 3p8.
  4. Then I set the DC actuation to -2000 counts and turned the AC actuation on. The IM vertical OSEMs seem to be completely free from any stop and follow the actuation. Pictures 4p1, 4p2, 4p3. The BF follows the actuation also.
  5. I removed the sinusoidal actuation completely and kept the AC one. The BF oscillates with a very low frequency again. See 5p1, 5p2.
  6. I removed the DC actuation completely. The low frequency oscillation in BF is gone. See 6p1.

Assessment of F1

Conclusions

It seems that when the keystone is placed around zero (original nominal) and above, a coupling with other mechanical elements appear. This manifests itself as persistent oscillation above 310 mHz, the decrease in the height of a peak in transfer functions, change in its frequency and a decrease of coherence below such a frequency. The system seems to be free of stray couplings at -572 um or below. However, a clear boundary between healthy and unhealthy behaviour has not been established yet.

Conditions

Desription of measurements

  1. I left F1 keystone at -182 um (10,000 counts of actuation) free swinging last night and, despite the time elapsed, the oscillation at 312.5 mHz has not damped (picture 1p1, 1p2). It has an amplitude of 30 um-pp. I assume it continues because the excitation hasn't ceased. The transfer function looks very good (1p3) but the resonant frequency is at 273 mHz not at 312.5 mHz.

  2. I removed the actuation and the keystone goes down to -572 um. The large oscillation at 312.5 mHz is gone; we see the highest peak at the resonant frequency of 281 mHz (pictures 2p1, 2p2, 1p3). The transfer function looks very good. The peak shows up at 273 mHz not at 281 mHz (picture 2p4).

  3. I turned the actuation on again (10,000 counts, keystone at around -182 um). The large oscillation is back, this time at 304 mHz, together with other oscillations in that frequency neighborhood (pictures 3p1 and 3p2). Then I turned the control system on, damping only, but it didn't damp it. I increased the gain but it became unstable. I don't have the TF in Foton to check the UGF and gain, so I gave up damping it.
  4. I increased the actuation to 14,400 counts to bring the keystone around zero. The oscillation is still there (pictures 4p1, 4p2) and it appears in a slightly higher frequency, at 328 mHz. The transfer function shows an unhealthy system: the peak around 280 mHz is gone and a shorter peak appears at 304 mHz instead (picture 4p3). The coherence at that frequency is also high for a resonance (0.91).The coherence at low frequencies does not look as good.

  5. I increased the actuation to 25,000 counts, which brought the keystone to around 450 um. The large oscillation is there (pictures 4p1, 4p2) at 320 mHz. The transfer function shows again an unhealthy system with the resonance at 320 mHz and with lower coherence below the first resonance (picture 5p3).

Klog for 16-11-2020

With Hiarata-san and Washimi-san.

Preparation from the control room

In situ preparation

Work inside the chamber

Type-B

With Washimi-san.

Type-Bp

With Washimi-san

General

About LVDT cards

[Fabian and Washim-san]

With the new information that Alessadro (Nikhef) provided a few weeks ago, we began measuring the settings in PR suspensions.

Type-B

[Fabian and Washimi-san]

Type-Bp

[Fabian and Washimi-san]

Type-B

[Fabian]

Possible activities for the next weeks (subject to Takahashi-san's approval):

Type B

Report for the week of the 19th of October 2020.

[Fabian]

General

Type B

Report of the week of the 12th of October

Type B

Report of the week of the 28th of Septermber

Type B

Report for the week of the 7th of September 2020.

Type B

Report for the week of the 27th of April 2020.

In the context of the Type-B paper I checked the noise level of the gephones: I did a calculation of the expected sensitivity and campared with Fujii-kun's measurements:

In the context of the writing

Type B

Report

Report

Report for the week 16-12-2019

Plan for next week

Report for the week 09-12-2019

Plan for next week

Vacation/Travel Info

Type B

Report for the week 23-09-2019

Plan for next week

Vacation/Travel Info

Report for the week 23-09-2019

Plan for next week

Vacation/Travel Info

Type B

Report for the week 13-09-2019

Type B

Report for the week 02-09-2019

Plan for next week

Report for the week 26-08-2019 (Written by Fabian)

Plan for the week 02-09-2019

Type B

Report for the week 15-08-2019 (Written by Fabian)

Plan for the week 19-08-2019

Type B

Report for the week 05-08-2019 (Written by Fabian)

Plan for the week 15-08-2019

Report for the week 7/29 (Written by Fabian)

Plan for the week 8/5

Type B

Report for the week 7/22 (Written by Fabian)

Plan for the week 7/29

Vacation/Travel Info

Type B (Mark)

Report for the week 7/15 (Written by Fabian)

Plan for the week 7/22

Vacation/Travel Info

Type B (Mark)

Report for the week 7/8 (Written by Fabian)

Plan for the week 15/8

Vacation/Travel Info

Type B (Mark)

Report for the week 7/1 (Written by Fabian)

Plan for the week 7/8

Type B (Mark)

Report for the week 6/24 (Written by Terrence and Fabian)

Plan for the week 7/1

Vacation/Travel Info

Type B (Mark)

Report for the week 6/17

Plan for the week 6/24

Vacation/Travel Info

Type B (Mark)

Report for the week 6/10

BS

Type B (Mark)

Report for the week 6/3

SRM Inertial Damping and Residual Motion Stuff

RMS Displacement:

Requirement

Result

L

0.4 µm

0.1076 µm

P

1 µrad

0.0569 µrad

Y

1 µrad

0.0598 µrad

RMS Velocity:

Requirement

Result

L

0.5 µm

0.1014 µm/s

P

/

0.2165 µrad/s

Y

/

0.1776 µrad/s

SR3 Inertial Damping

Type B (Mark)

Report for the week 5/27 (written by Fabian)

Type B (Mark)

Report for the week 5/20 (written by Fabian)

Plan for the week 5/25

Report for Golden Week

Report for the week of 5/6

Report for week of 5/13

Plan for week of 5/20

Vacation/Travel Info