Vibration Zeroing at Specified Frequencies in a Cryopump with an Active Dynamic Vibration Absorber

Abstract

Cryopump is a vacuum apparatus used in various high-accuracy measurement systems such as those for detecting gravity wave and observing micro motion of molecules. However, the pump induces vibrations with multiple frequencies, which may deteriorate measurement accuracy. To overcome this problem, a vibration isolation apparatus with an active dynamic vibration absorber has been developed. This study focuses on removing the vibration of low frequencies because conventional vibration isolation devices for cryopump hardly remove them. A controller is designed based on the internal model principle to remove the vibration at several specified low frequencies. In the experiment, the vibrations at four specified frequencies are reduced to virtually zero with the implemented controller.