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Background
The Waves and Beams Division, headed by
PSFC Associate Director Dr. Richard Temkin,
conducts research on novel sources of electromagnetic
radiation, and on the generation
and acceleration of charged particle beams. All
research programs within the Division emphasize
substantial graduate student and postdoctoral
associate involvement. High-power microwaves
are needed for scientific, industrial, military and
medical applications, including: heating hightemperature
plasmas in nuclear fusion energy
research; accelerating high-power beams of electrons;
processing materials in the semiconductor
and ceramics industries; advanced radar systems;
and electron and nuclear magnetic resonance
spectroscopy. Intense beams of charged particles
have scientific, industrial and medical applications,
such as high-energy and nuclear physics
research, heavy ion fusion, cancer therapy and
homeland security.
Recent Research Activities
Gyrotron Research
Gyrotrons are under development for electron-cyclotron
heating of present day and future plasma
devices, including the ITER and DIII-D tokamaks;
for high-frequency radar; and for spectroscopy.
These applications require gyrotron tubes operating
at frequencies in the range 90-500 GHz
at power levels of up to several megawatts. In
recent research, the Gyrotron Group has been
investigating the operating characteristics of a
1.5 MW, 110 GHz gyrotron with an internal mode
converter and a depressed collector. The goal
is to improve the efficiency of these gyrotrons
and to extend their performance to frequencytunable
operation.
A novel internal mode converter has been designed,
built and tested for improvement of the gyrotron
output beam quality. The new mode converter
uses smoothly varying mirror surfaces, which are
easier to fabricate and less sensitive to alignment.
Testing showed excellent agreement between the
theoretical predictions and experimental results.
Research is now underway on understanding in
far greater detail the mode competition that
occurs in gyrotrons utilizing highly overmoded
resonators. The sequence of modes
excited during the turn-on of the MIT gyrotron
has been m e asure d o n a nanosecond time
scale, and is being compared with theory. The
modes excited during the voltage rise of the gyrotron
have been predicted by the multi-mode,
time-dependent code MAGY written by
scientists at the University of Maryland and the
Naval Research Lab. Our results show that the
code may need to be refined to properly predict
the results observed in the experiments. Future
research will concentrate on increasing the
power level of gyrotrons to the multi-megawatt
range and to demonstrating frequency tuning
over a wide range. This research is funded by the
US DOE Office of Fusion Energy Sciences and is a
collaborative effort with General Atomics, Communications
Power Industries (CPI), Calabazas
Creek Research, Tech-X Corp., University Maryland
and University Wisconsin.
Accelerator Physics Research
The research effort on high-gradient accelerators is
focused on high-frequency linear accelerators for
application to future
electron colliders. In
recent research, the
Accelerator Research
Group continued operation
and improvement
of the Haimson
Research Corporation
25 MeV, 17 GHz electron
accelerator. This
is the highest power
accelerator on the MIT
campus and the highest
frequency standalone
accelerator in the
world. The accelerator
laboratory has been
upgraded for operation
of a novel highpower
17 GHz source,
a Choppertron, built
by Haimson Research.
We have also installed
a dedicated test line
for measuring high-
Graduate student David Tax works with the 1.5 MW, 110 GHz
gyrotron and superconducting magnet.
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