aLIGO LHO Logbook

H1 SUS (CSWG, ISC)

jeffrey.kissel@LIGO.ORG - posted 17:02, Tuesday 02 August 2022 - last comment - 17:06, Tuesday 02 August 2022(64295)

Recently Installed HLTS Damping Loops Reduce Qs of all Modes As Designed

J. Kissel

In order to assess the performance of the recently installed "Level 2.1 design" of the HLTS damping loops (design: G1400151, which is just a pointer to LLO:7907, installation: LHO:64152), I've taken the standard "health check" transfer functions, but comparing with these new damping loop filters ON vs. OFF. (This test is more comprehensive and easier to interpret than a step-function / ring-down test, so we therefore won't need to do those test).

Comparing the attached pages of today's results against the plum-colored, dashed, "MIMO Closed loop / 100" traces on pages 4, 11, 18, 25, 32, and 39 for L, T, V, R, P, and Y respectively, shows that the loops work as designed, and we get the expected amount of Q reduction for all resonances in all DOFs, while achieving much better sensor noise rejection about ~10 Hz. 

Nice work Elenna and Evan!

Measurement details will be posted in the comments.

Non-image files attached to this report

allhltss_2022-08-02_H1SUSPR3_M1_Phase3b_DampedvsUndamped_ALL_ZOOMED_TFs.pdf

Comments related to this report

jeffrey.kissel@LIGO.ORG - 17:06, Tuesday 02 August 2022 (64296)

Link

The raw data for these two measurements can be found here:
    /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/PR3/SAGM1/Data/
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_L_0p01to50Hz.xml   # Undamped
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_P_0p01to50Hz.xml
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_R_0p01to50Hz.xml
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_T_0p01to50Hz.xml
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_V_0p01to50Hz.xml
        2022-08-02_2008_H1SUSPR3_M1_WhiteNoise_Y_0p01to50Hz.xml

        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_L_0p02to50Hz.xml   # Damped
        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_P_0p02to50Hz.xml
        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_R_0p02to50Hz.xml
        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_T_0p02to50Hz.xml
        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_V_0p02to50Hz.xml
        2022-08-02_2041_H1SUSPR3_M1_WhiteNoise_Y_0p02to50Hz.xml


Because the undamped transfer functions are the same as our "health check" transfer functions, I post here the processed data for the individual measurement that shows off-diagonal cross-coupling and OSEM basis response.

Non-image files attached to this comment

2022-08-02_2008_H1SUSPR3_M1_ALL_TFs.pdf