Erl 07-1 Thermal Expansion Coefficients of Some Materials Used for Hom Load Absorbers

INTRODUCTION For HOM loads proposed for the Energy Recovery Linac injector cavities we used different materials for absorption, two kinds of ferrites and a ceramic-like material with a trade name “ceralloy”. These materials were brazed or soldered to a metal substrate. One important requirement to the bonding of absorbers and substrate is a very large temperature range where a good mechanical and thermal contact is needed: from the highest temperature of bonding to 77 K. Such a low working temperature was chosen to accommodate the HOM load inside the cryomodule close to the superconducting cavities at 2K. The necessary condition for reliable bonding of absorber and substrate is a close correspondence between their coefficients of thermal expansion. Some details for the choice of these pairs are discussed in this paper.