KAGRA Logbook

VIS (SRM)

enzo.tapia - 14:43 Tuesday 17 April 2018 (4721)

Keystone adjustment range for BF and SF for SRM

On Wednesday 11.04, Thursday 12.04 and Monday 17.04 with Kozu-kun and Hirata-san:

After completing the calibration of the LVDTs, we checked the performance of the fishing rod (FR) moving the stepper motor of SF for SRM suspension.

The FR height is measured from the metal base plate of the stepper motor to the top of the PEEK plate. See picture 1.

For SRM_BF (BF_No1):

We prepared the load of 52.176[kg] to set the keystone at nominal position (65.5 [mm]).
The fishing rod height range is from 19.8 [mm] to 50.7 [mm].
The keystone adjustment range (using the fishing rod) is from 62.5 [mm] to 68.3 [mm].

So the keystone can be moved around +/- 2.8 [mm] from the nominal position. See figure 2.

For SRM_SF (SF-B2-5):

We prepared the load of 166.301 [kg] to set the keystone at nominal position (65.5 [mm]).
The fishing rod height range is from 19.8 [mm] to 54.4 [mm].
The keystone adjustment range (using the fishing rod) is from 63.8 [mm] to 66.9 [mm].

So the keystone can be moved around +/- 1.4 [mm] from the nominal position. See figure 3.

Then we took away the BF and the SF and we placed them in a corner near the MCe area.

Note 1: The SF for SRM might be rubbing somewhere, because it was difficul to move the keystone between 65.0 and 64.0 [mm]. We should inspect it carefully when we bring the filter inside the cleanbooth again.

Note 2: The filters were without the cap when the data was taken.

Images attached to this report

Comments to this report:

yoshinori.fujii - 20:54 Tuesday 17 April 2018 (4728)

Thanks for these measurements! Just for check, was the keystone height measured by the LVDT? I just want to confirm that all the measyred data was inside the LVDT linear range properly. Also, the keystones were not touching anywhere during the measurement except for the SRM-SF (SF-B2-5), it that correct?

enzo.tapia - 12:15 Thursday 19 April 2018 (4747)

The keystone height was measured with a ruler (the same way as for the LVDT calibration).

About to the linear range of the filters, and summarizing what we did:

For SR3:

SR3-BF Linear range: 64[mm] to 66.5[mm].
The FR can move the Keystone down from nominal position to 64.2[mm] and can move it up to 66.5[mm].

SR3-SF Linear range: 63.5[mm] to 68[mm].
The FR can move the Keystone down from nominal position to 63.5[mm] and can move it up to 67.5[mm].

For SRM:

SRM-BF Linear range: 62.5[mm] to 69.5[mm].
The FR can move the Keystone down from nominal position to 62.5[mm] and can move it up to 68.4[mm].

SRM-SF Linear range: 62[mm] to 69[mm].
The FR can move the Keystone down from nominal position to 63.8[mm] and can move it up to 66.9[mm].

So the FR can move the keystone within the linear range of the LVDT for the corresponding GAS filter.

And yes, by visual inspection the keystone were not touching anywhere but for the SRM-SF we will inspect it again next time.