[Ikeda, Takahashi]
We checked the EQ stops of the SR3 payload. The pictures are archived in the KAGRA Dropbox.
[Ikeda, Takahashi]
We checked the EQ stops of the SR3 payload. The pictures are archived in the KAGRA Dropbox.
[Ikeda, Takahashi]
We checked the EQ stops of the SR2 payload. The pictures are archived in the KAGRA Dropbox.
[Ikeda, Takahashi]
We checked the EQ stops of the SRM payload. The pictures are archived in the KAGRA Dropbox.
Yokozawa, Washimi, Tanaka
### Abstract
We stomped the ground around MCF and MCE chamber with locking IMC to check the resistance for the blasting. However, we could shake the ground around MCF and MCE chamber at most +/- 60~70 um/s and IMC could keep the lock during our stomping. According to IMC LSC feedback signal to the laser PZT (K1:IMC-SERVO_SLOW_DAQ_OUT_DQ), when the ground shaked +/- 60~70 um/s, the amplitude of the feedback signal became +/- 0.2 V at 1 Hz (which is the length resonance frequency of Type-C sus.). If the blasting shake the ground with the amplitude of 200 um/s, which is estimated by the construction company, the feedback signal is expected to become +/- 0.6~0.8 V. This value is in the range (+/- 5V) so IMC will be able to keep the lock during the blasting. At worst, IMC lock can restore by guardian automatically even if IMC goes down.
### What we did
I redesigned the MN_NBDAMP_DOF5 filter not to oscilate at LOCK_ACQUISITION state.
At 296K, ETMX forth L resonance is about 5.04 Hz while it was 5.13 at 90K.
So, I made new filter (BP5.04(296K)) at FM1 of DOF5 and moved old filter from FM1 to FM2.
After changing the filter, damping seems working well (fig1).
Figure 2 show the one hour trend of PS DAMP signals at LOCK_ACQUISITION state after changing the filter.
For one hour, no oscillation can be observed, so the control seems stable.
Note that the TFx and TFy are the vertical -> horizontal coupling in this shaking test, but were the horizontal -> horizontal coupling in the previous hammering test. So their comparison is not fair.
HWP vs IMC trans power relationship
HWP [degree] | IMC trans [W] |
7 | 1.45 |
8 | 1.72 |
9 | 2.0 |
10 | 2.3 |
11 | 2.6 |
12 | 2.9 |
13 | 3.25 |
14 | 3.6 |
15 | 3.9 |
16 | 4.25 |
17 | 4.65 |
18 | 5.0 |
19 | 5.3 |
20 | 5.7 |
HWP vs IMC trans power relationship
HWP [degree] | IMC trans [W] |
7 | 1.45 |
8 | 1.72 |
9 | 2.0 |
10 | 2.3 |
11 | 2.6 |
12 | 2.9 |
13 | 3.25 |
14 | 3.6 |
15 | 3.9 |
16 | 4.25 |
17 | 4.65 |
18 | 5.0 |
19 | 5.3 |
20 | 5.7 |
I took the picture 21st May. (Tuesday)
[miyoki, uchiyama, hayakawa, yoshimura, yamaguchi, omae, takahasi, sawada]
Progress
We filled the cleaning water just above the bottom surface of the optical table. We left it for one night.
Cleaning Process
Tomorrow plan
I checked the TFs measured in air. They are consistent with the reference (measurement before O4a) and look healthy.
Over the last few days I have been trying to understand the reason for the instability of the 30 mHz blending strategy along the T direction. As already mentioned, the T TF still shows the phase lag visible in the TFs measured with the blended sensor, despite the phase compensator implemented to compensate for it. As with the EX, I first modified the phase compensator to avoid DC saturation of the ACC and GEO (see Figure 1, Figure 2, Figure 3, and Figure 4), and then measured the TFs: LVDT/IS{L,T}.
Figure 5 and Figure 6 show the TF: LVDT/IS{L,T}. It is clear that there is still a phase lag which introduces instability into the loop. To reduce the phase lag, I implemented a new phase compensator on the virtual inertial sensor. I then re-measured the TFS and it seems that it helps to reduce the phase lag and should stabilise the loop (see Figure 7, Figure 8).
Next step:
Test the stability of the loop and redesign the blend filters.
I calculated the transfer functions from the base vibration (z) to the table vibration (x,y,z).
Comparing the results of hammering (klog29515), inconsistency is found.
The underestimation below 70Hz is solved.
I performed the shaker injection tests for the OMC base plate, by locating a 3-axial accelerometer (TEAC710Z) on the optical table and a 1-axial accelerometer (TEAC710, for vertical) on the base plate.
I calculated the transfer functions from the base vibration (z) to the table vibration (x,y,z).
Comparing the results of hammering (klog29515), inconsistency is found.
The underestimation below 70Hz is solved.
Note that the TFx and TFy are the vertical -> horizontal coupling in this shaking test, but were the horizontal -> horizontal coupling in the previous hammering test. So their comparison is not fair.
I performed actuator and center balancing of ETMY to confirm strange MNV TF can be better by sensor/actuator decoupling.
Figure 1 shows the MNV TF after decupling.
MNV TF becomes healthy.
Also, I measured TFs from V1 and V3 coils (fig6: V1, fig7: V3).
Since the gain of V1 becomes smaller, the gain of TF is smaller than before but it is not problematic.
Also, gain of MN V3 is now same as the reference, so the smaller gain, which was measured previously, seems due to the gain change in DGS.
So, MN stage TF seems fine now.
What I did:
1. Photosensor gain (MN_OSEMINF_{H1,H3}_GAIN) was changed to minimize the coupling between MNV and MNP (fig2:before, fig3:current).
2. Actuator balance was performed for reducing V2P coupling (fig4: before, fig5:current).
3. V2Y actuator decoupling was performed (fig6)
Is this actual number of the pressure inside IFI-IMM-PRM chambers?? I wonder if the GV between this CC-10 and the IFI-IMM-PRM chambers might open ot not.
[Kimura]
The serial communication settings on the replaced CC-10 were reset to factory settings, but the connection to the network was not restored.
Therefore, the electronic board of the CC-10 was replaced with the removed CC-10 electronic board and the sensor calibration curve was reset.
As a result, the connection to the network was restored. (Figure 1)
The values were confirmed to be consistent with the displayed values seen by the network camera. (Photo 1)
The CC-10 with communication failure will be sent for repair.
At 11:16 a.m., CC-10 indicated 8.0 x 10^-5 Pa.
Around 9:00, 8.2x10^-5 Pa.
Around 10:00, 1.0x10^-4 Pa.