Improvement of thermo-mechanical position stability of the beam position monitor in PLS-II

TL;DR

This paper presents methods to improve the thermo-mechanical stability of beam position monitors in PLS-II, reducing displacement caused by heating to ensure precise electron beam positioning.

Contribution

The study introduces improved support and cooling techniques for BPM vacuum chambers, enhancing their stability during operation.

Findings

Reduced mechanical displacement of BPMs after improvements.

Enhanced stability of electron beam position during operation.

Thermo-mechanical analysis confirms effectiveness of modifications.

Abstract

In the storage ring of PLS-II, we reduced mechanical displacement of electron beam position monitors (e-BPMs) that is caused by heating during e-beam storage. The orbit feedback system intends that the electron beam pass through the center of the BPM, so to provide stable photon beam into beamlines the BPM pickup itself must be stable to sub-micrometer precision. Thermal deformation of the vacuum chambers on which the BPM pickups are mounted is inevitable when the electron beam current is changed by unintended beam abort. We reduced this deformation by improving the vacuum chamber support and by enhancing the water cooling. We report the thermo-mechanical analysis and displacement measurements of BPM pickups after the improvements.