Stabilizing methods against mechanical vibrations of vacuum exhaustion units on BL11XU at SPring-8

Kiriyama, Koji; Shiwaku, Hideaki   

Stabilizing methods for vacuum exhaustion units in the optics section of the beamline have been developed on BL11XU at SPring-8. In this study, we especially focus on the vibrations from scroll pumps in the vacuum exhaustion units. Vibration frequencies were measured directly on the scroll pump under multiple conditions. From these measurements the following countermeasures were found to be dramatically effective for restrain on the 30Hz vibration from (1) to use a damper for scroll pump, (2) not to attach the scroll pump to a vacuum unit support but to put it on directly on the floor, and (3) to settle flexible tubes and the scroll pump on the floor. These methods successfully removed the mechanical vibrations of the scroll pumps. As a result, the amplitude of the 30Hz vibration on the monochromator crystals was decreased from 3.310-5mm to 6.210-6mm. The proposed methods in the present study on BL11XU can be applied to the similar vacuum units at the other beamlines.