From the Director - Plasma Science and Fusion Center - MIT

with the depressed collector agree with this
theory. The observed efficiency of gyrotrons
built and tested at many laboratories
around the world is now being investigated
to see whether the same efficiency-reducing
effect is present in those gyrotrons. An
intensive program of theoretical research is
being undertaken to design a new gyrotron
that will have substantially higher
efficiency. The goal is to achieve at least
60% overall efficiency in the near term.
This research is funded by the US DOE
Office of Fusion Energy Sciences and is a
collaborative effort with General Atomics,
CPI, Calabazas Creek Research, University
Maryland and University Wisconsin.
ITER Transmission Line Research
The US is responsible for designing, building
and fabricating the transmission line system
for electron cyclotron heating and current
drive on ITER. MIT is conducting research
on the losses in transmission line components
in collaboration with the US ITER Project
Office, Oak Ridge National Lab; General
Atomics; and the JAEA Laboratory in Japan.
The transmission lines will be carrying 24 MW
Graduate student Eunmi Choi in the Gyrotron Research Laboratory.
of power over more than 100 meters of path
length, so that losses in the lines must be kept
to the absolute minimum. The largest loss in
the line occurs at the 90 degree miter bends,
where 0.6% loss is expected theoretically.
This is a small fractional loss, but represents
144 kW of power lost from a 24 MW microwave
heating system! MIT is now attempting
to measure this loss in individual miter
bends and to derive theoretically the nature
of conversion to high order waveguide modes
Postdoctoral Associate Seong Tae Han and the 170 GHz Microwave Test Laboratory.
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