HEX 2-piece ID Absorber: Steady and Transient Thermal FEA

Abstract

Radiation fans from Insertion Devices and Bending Magnets are “trimmed” by various water-cooled absorbers located strategically downstream of those sources. Mostly, the absorber surfaces onto which power is deposited are constructed from Glidcop Al-15 (rarely OFHC copper). On the basis of Tech Note 327 a re-design for improved thermal performance has evolved to a two-piece ID Absorber configuration; one between dipole chamber and quadrupole, another after the sextupole, each with reduced incident angle. The ring’s Active Interlock (AI) system protects against overheating by disabling mis-steered beam within an allotted time. SRP (Synchrotron Radiation Protection) protocol has a limiting maximum allowable temperature of 100*C at any point when subject to mis-steered beam for a fixed period before AI activation. After 0.2 msec, radiation exceeding +/- 0.5mm offset and +/- 0.25 mrad angular error from the HEX SCW will trip in fault. AI specification allows 1.0 msec to fully dump the electron beam.