||The TESLA input coupler has to
transmit pulses up to 1MW RF peak power and at an average up to 300 kW
for an 800 us long beam pulse. The transmission line parts should
combine low heat conductivity and high electrical surface conductivity.
Therefore stain less steel pipes or bellows are plated by a thin copper
layer (10-20 um) at the RF surface. Such parts are exposed to high
temperatures in a UHV furnace during fabrication and treatment.
Influence of copper thickness, coating technique and annealing
parameters on the microstructure, RRR, electrical and thermal
conductivity is investigated. Two processes take place during heat
treatment. On one hand occurs the recrystallization of copper that
positively influenced the required parameters, on the other hand the
diffusion of elements from stain less steel at high temperatures can
significantly pollute the copper and reduce the electrical properties
of the layer. Reasonable parameters of the heat treatment for
electrodeposited copper layers are defined.