KAGRA VIS Operations Manual - Health Check for Type B Suspensions

This page describes how to do a health check on a Type B suspension.

Stuff to Add

Vertical Height Check

The vertical height budgets for the suspensions are described in the data pages at





For operation in vacuum, aim to meet the height budget as much as possible with GAS FR stepper adjustments, and minimize any LVDT actuation.

For operation in air, aim to leave the GAS FRs as close as feasible to the positions for in-vacuum buoyancy correction and meet the height budget with LVDT actuation. However note that the coil drivers trip at somewhere around 25000 counts of output, and the COILOUTF filters are set to have a LIMIT of 20000 to minimize the chances of this happening. Therefore if you find LVDT actuation near to or above 20000 counts is required, feel free to use some FR adjustment.

Note that the SR3 SF (=F1) FR is jammed and does not move.

For both in-air and in-vacuum operation it is very important that the BF GAS is near 0 ┬Ám, because this puts the IM-V OSEMs at mid-range and the IM-H with optimum clearance. Fortunately this is normally easily achieved in air with just LVDT actuation.

Transfer Functions

Scripts for automated taking of TFs are at /kagra/Dropbox/Subsystems/VIS/TypeBData/scripts/.

The script creates a new folder under /kagra/Dropbox/Subsystems/VIS/TypeBData/XXX/TF/Measurements/YYYYMMDD/ where XXX is the name of a suspension (BS/SR2/SR3/SRM) and YYYY, MM and DD refer to the current date.

Caveats (as of 2019-04-05)


./run_measurement_IM XXX
./run_measurement_GAS XXX
./run_measurement_IP XXX

KAGRA/Subgroups/VIS/OpsManual/TypeB/HealthCheck (last edited 2019-04-05 11:53:39 by MarkBarton)