Brazing of High Performance, Passively Cooled, Heat Absorbing Mirrors for Electron Cyclotron Heating Launchers
Authors: S.Z. Jurczynski, R.A. Ellis, J.C. Hosea, H. Grunloh and J. Lohr
Abstract:
Electron Cyclotron Heating is essential for the operation of
high performance plasma fusion experiments. A 6 cm diameter, 1 MW, 110GHz beam is typically guided to a
specific location by a steerable mirror. This mirror is subject
to design requirements that work against each other. High heat
loads, and absence of convective cooling dictate a mirror
made from conductive material with a significant heat
capacity and mass. These qualities tend to increase
electromagnetic forces on the mirrors, complicating the design
of the mirror supports.
A successful design compromise has been to make the mirror
as a brazed assembly with stainless steel bars inlaid into a
copper block. As power levels and pulse lengths increase, the
use of higher strength copper alloys has been explored.
Chrome Zirconium Copper, [C18150] has emerged as an
attractive candidate for mirror construction. The zirconium,
however, causes difficulties in brazing. We have developed a
process that overcomes these difficulties, and also includes
heat treatment as part of the braze cycle, so that the strength of
the copper alloy is partially recovered after the high
temperature braze.
This paper describes the design challenges associated with
ECH launcher mirrors, the development of a high temperature
braze technique for C18150, and the latest mirror design.
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Submitted to: Proceedings for IBSC 2012 5th Annual Brazing and Soldering Conference, Las Vegas, NV April 22-25, 2012
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