Mirror actuation design for the interferometer control of the KAGRA gravitational wave telescope

TL;DR

This paper presents a detailed simulation model for the mirror actuation system of the KAGRA gravitational wave detector, enabling optimized control parameters to achieve precise mirror positioning without excess noise.

Contribution

The paper introduces a comprehensive simulation model for KAGRA's mirror actuation, aiding in the design of effective control parameters for interferometer lock acquisition.

Findings

Designed actuation parameters with sufficient force range

Achieved control of all length degrees of freedom

Ensured no excess noise introduction

Abstract

KAGRA is a 3-km cryogenic interferometric gravitational wave telescope located at an underground site in Japan. In order to achieve its target sensitivity, the relative positions of the mirrors of the interferometer must be finely adjusted with attached actuators. We have developed a model to simulate the length control loops of the KAGRA interferometer with realistic suspension responses and various noises for mirror actuation. Using our model, we have designed the actuation parameters to have sufficient force range to acquire lock as well as to control all the length degrees of freedom without introducing excess noise.