Trifilar torsion pendulum for measurement of dissipation caused by an electric field

A trifilar all-fused silica pendulum with a Q factor exceeding 10(7) is described. This pendulum has been used to study the damping caused by an electric field applied between the suspended mass and a nearby electrode. Among the different loss mechanisms the most interesting one is associated with the surfaces of the electrodes. Application of a field of 10(6) V/m added an excess loss Q(e)(-1) of at least 10(-7). These results are important for laser interferometer gravitational wave detectors since electrostatic actuators are supposed to be used in order to precisely align the cavity mirrors. (C) 2000 American Institute of Physics. [S0034-6748(00)03710-2].