[Takahashi, Ikeda]

We started the recovery of the MCo suspension.

1. Adjusted the Yaw pico-motor to the midpoint.
2. Released the IM from the magnets on the magnet box (IRM) by moving the suspension point for the box.
3. Adjusted the pico-motors so that the Oplev can be centered. Then the Yaw pico-motor has gone to the actuation limit again.
4. Adjusted the Yaw pico-motor to the midpoint.
5. Set the stop screw jigs at the corners of the frame. Released the screws fixing the frame to the spacer plate. Rotated the frame with two orthogonal stop screws so that the Oplev can be centered. Then the frame was aligned to the spacer plate and the breadboard. Fastened the screws to fix the frame to the spacer plate. The jigs were removed.
6. Checked the gap between the EQ stoppers and TM and the gap between the damping magnets and IM.

The TM moved smoothly during the operation of the pico-motors. We found the final fallen magnet on the EQ stop frame. 

I checked the magnets to be glued to the TM. The diameter of the first ordered magnets (1.5mm) did not fit the gluing jig with an inner diameter of 1.7mm. The diameter of the second ordered magnets (1.65mm) fitted the jig.

[Takahashi, Dan, Washimi, Ikeda]

• We removed the spacers between the coil bobbin adapter and the frame. The spacers have been used to adjust the gap between the coil and the magnet in the last condition.
• We checked if the magnet gluing jig could fit the coil bobbin. We could not insert the jig into the H4 bobbin due to the residual glue inside the bobbin which has been ever repaired by gluing.  The ceramic bobbin was chipped during the trial of insertion.
• Though we found some spare bobbin adapter, I could not find spare bobbins in the KAGRA site. we will search in Mitaka.

I found four sets of coil bobbins with the adapter in the 20m Lab (Mitaka).

We measured the inductance and resistance of the coils.
(Each coil is marked with a number on it.)

LCR-9183 and FLUKE 177 were used to measure.

After the measurement, we cleaned the coils with ethanol and ultrasonic cleaner.

Well, I can say the #2 would be a "different" one, or the way to measure the inductance might differ...

By the way, what are the inductances and resistances of the currently-used coils for MCo??

The specifications of the current actuator coils are recorded in the acceptance check document. Inductance was 37~39μH.

I took the broken H4 coil out from the MCo suspension. On the other hand, I found a spare coil that has the same dimensions and similar specifications.

The measured specifications are as follows.

I cleaned the coil by a ultrasonic cleaning machine for 10 min with Ethanol.

It is still in the draft chamber to dry.

[Washimi, Takahashi]

We replaced the H4 coil and glued the magnets onto the TM.

1. Fixed the TM with the EQ stoppers. Before that, we had touched the suspension wire, so the TM was misaligned. Took the alignment to the Oplev with the pico-motors again.
2. Cramped the pins to the lead cable of the spare coil. Resistance was 3.6Ω and inductance was 38.8μH.
3. Connected the coil to the cable from the Dsub connector. The coil with an adapter plate was attached to the frame. The lead cable was fixed on the frame with PEEK ties.
4. Adjusted the position of the coils to the seals of the last gluing. Since the seals disappeared for the H3 and H4 coils, adjusted symmetrically with the H1 and H2. The TM was rotated in CCW from the HR side a little (photo).
5. Glued the magnets (1.65φ x 5t) to the TM with the jigs. The polarity (flux) was N (251mT) for H1, S (257mT) for H2, N (280mT) for H3, and S (269mT) for H4 respectively.

[Washimi, Takahashi]

We released the glued magnets. All magnets were fixed completely. We checked the signs of the actuation by applying offsets of 3000 counts to each coil in COIOUTF. The results were reasonable as follows.