KAGRA VIS Operations Manual - LVDT

LVDTs are used for vertical sensing and actuation in all the GAS filters and for horizontal sensing and actuation in all the IP stages.

See LVDT Signal Conditioning for useful background on LVDT demodulation.

See JGW-T1201255 for description of the Nikhef-supplied cards, and JGW-T1604798 for more information on how to tune the demodulation circuit.

LVDT Calibration Procedure: JGW-E1707287 or LVDT Calibration Procedure.

LVDT Coil and Driver Data

Type A

Test Mass Suspensions

Type B

BS and SR suspensions

BS Data

SR2 Data

SR3 Data

SRM Data

Type Bp

PR Suspensions

Type C

Modecleaner Suspensions

Yoke Height Settings

The yoke should be set so that the double and single LVDT coils are symmetrically aligned when the keystone is at nominal height. It is convenient to set this in terms of the amount the PEEK coil former sticks out above the filter baseplate.

Bottom Filter (BS and SRx)

Note that the CAD is wrong for the bottom filter yoke:

YokeHeightExample.pngKeystoneHeightExample.png

Standard Filter (BS and SRx)

YokeHeightExampleSF.png

Top Filter (BS and SRx)

YokeHeightExampleBSF0.pngYokeHeightExampleSRF0.png

Summary

GAS Filter

Yoke Height

Keystone Height

BS BF

3.5 mm

65.5 mm (up from baseplate)

SR BF

3.5 mm

65.5 mm (up from baseplate)

BS SF

6 mm

65.5 mm (up from baseplate)

SR SF

6 mm

65.5 mm (up from baseplate)

BS F0

36 mm

153 mm (up from top plate), 16.5 mm (down from ring)

SR F0

34 mm

151 mm (up from top plate), 16.5 mm (down from ring)

Type Bp Data

Your data here!

Stocktake

LVDT Stocktake as at 2018-04-13

See JGW-D1402826-v2: LVDT Driver Module Top Assembly.

* = sighted recently

Faulty (3)

In use, presumably OK (14)

In use, needs new front panel (1)

In circuit room (11)

In circuit room, needs new front panel (1)