MIT
Reports to the President 1994-95
The Plasma Technology and Systems Division, headed by Dr. Daniel R. Cohn,
investigates plasma processing for environmental and industrial applications;
develops new diagnostic technology for environmental and fusion applications;
and investigates advanced fusion reactor systems designs and magnet concepts.
Current research areas include arc plasma treatment of solid waste (Daniel R.
Cohn, Paul P. Woskov, Charles H. Titus, and Jeffrey E. Surma); process
diagnostic development (Paul P. Woskov and Daniel R. Cohn); cold plasma
processing of gaseous waste (Daniel R. Cohn and Leslie Bromberg); plasma
manufacturing of hydrogen (Daniel R. Cohn and Leslie Bromberg); millimeter wave
and infrared diagnostic development (Paul P. Woskov); system studies (Leslie
Bromberg); high temperature superconducting magnet development (Leslie
Bromberg); and fusion safety and environmental studies (Mujid S. Kazimi). Some
highlights of our research in the past year are listed below.
A pilot-scale arc plasma research furnace to study treatment of simulated solid
waste has been operated with continuous feed. Power levels in the 250 kW range
were used with a material feed rate of 200 pounds per hour. Soil
characteristic of the Idaho National Engineering Laboratory (INEL) has been
converted into a stable glass. The furnace has also been used for extensive
testing of process diagnostics. Future objectives include studies of
vitrification of a range of simulated wastes; development of predictive models
and their applications to control systems (with Prof. Julian Szekely of the
Materials Science and Engineering Department); and component testing.
An active millimeter-wave pyrometer has been developed to measure furnace and
material temperatures in a hostile environment. The device has been
successfully tested in the Mark 2 furnace. A 1994 R&D 100 Award was
received for this work. A microwave plasma analyzer for continuous monitoring
of metals in smoke stack emissions has also been successfully tested on the
Mark 2 furnace. A 1995 R&D 100 Award for this technology has been
announced recently. In addition to application to waste treatment in plasma
furnaces, the capability for continuous monitoring of metals emissions could be
applied to incinerators, waste to energy plants, and fossil fuel power
plants.
We have shown in the laboratory that low temperature plasmas generated by
moderate energy (100-300 keV) electron beams can be used to selectively destroy
dilute (1-1000 ppm) concentrations of volatile organic compounds (such as
carbon tetrachloride and trichloroethylene) in air streams. The high degree of
selectivity results in a highly efficient relatively low cost process. This
system is attractive to DOE for on-site treatment of solvents pumped out of the
ground in remediation activities and is also attractive for air stripping of
contaminated water. In 1995, a successful initial field test was carried out
at the DOE Hanford site. The test showed fully automated feedback controlled
operation.
Support from the DOE Hydrogen Research Program has been received in 1995 for
investigations of plasma manufacturing of hydrogen. Experiments are underway
to determine the effectiveness of arc plasma technology in converting
hydrocarbons into hydrogen-rich gas. Potential applications include use with
fuel cells. Prof. Simone Hochgreb from the Mechanical Engineering Department
is participating in this activity.
A gyrotron scattering system for alpha particle diagnostics has been tested on
the TFTR tokamak at Princeton University. Scattering from relatively high
level nonthermal fluctuations was observed, which has prevented a simple
interpretation of these results. Meanwhile, collaborative efforts in
scattering experiments are also underway with the JET tokamak in Abingdon,
England. This activity, which will use a high power Russian gyrotron operates
in a different regime, has good prospects for making the first thermal
scattering measurements from alpha particles. These measurements are important
for understanding ignition physics and could play a key role in ITER.
The Waves and Beams Division, headed by Dr. Richard Temkin, conducts research
on novel sources of electromagnetic radiation and on the generation and
acceleration of particle beams.
The gyrotron is a novel source of microwave, millimeter wave and submillimeter
wave radiation. It uses a helical electron beam in a high magnetic field to
generate radiation by stimulated emission at the electron cyclotron frequency.
Gyrotrons are under development for electron cyclotron heating (ECH) of present
day and future magnetically confined fusion plasmas as well as for high
frequency radar. These applications require tubes operating at frequencies in
the range 100-300 GHz at steady-state power levels approaching 1 MW. The
gyrotron research group is led by Dr. Kenneth Kreischer.
Research has concentrated on investigating the physics issues which affect the
efficiency of operation of high power, high frequency gyrotrons. Efficiency is
a critical issue because it determines the recirculating power needed to
sustain a practical fusion reactor and also greatly impacts the reliability and
cost of plasma heating systems. We have begun a program of research to
demonstrate a high power, high frequency gyrotron suitable for application to
the International Thermonuclear Experimental Reactor (ITER). A prototype
experiment at M. I. T. has been built and is now under first testing. The ITER
Joint Central Team has approved the research phase of this project for credit
as part of the ITER program. The objective is to demonstrate a 1 MW, 170 GHz
gyrotron with an efficiency of at least 35%. This work will be carried out in
collaboration with Varian Associates, General Atomics, Univ. Wisconsin, Univ.
Maryland and Lawrence Livermore National Lab. The MIT gyrotron group has the
lead role in this effort.
A program of research is also underway to demonstrate a coaxial cavity
gyrotron. This experiment will be carried out at 140 GHz in collaboration with
Dr. Michael Read of Physical Sciences, Inc. of Alexandria, Virginia. In
principle, the coaxial cavity gyrotron may be capable of power levels up to 3
MW, significantly higher than the 1 MW power expected from conventional cavity
gyrotrons. The experiments will begin in the summer of 1995.
The Relativistic Beam Physics Group, led by Dr. Bruce Danly, investigates the
generation of high voltage electron beams and their application to high power
microwave generation. Research programs include investigations of the
cyclotron autoresonance maser (CARM), the free electron laser (FEL), the
relativistic klystron and the induction linear accelerator (ILAC).
Research is continuing on a high power, 17 GHz klystron in collaboration with
Haimson Research Corp. of Palo Alto, CA. The klystron electron gun is a gun
that was previously built for MIT and the klystron cavities were built by
Haimson Research. The klystron has now demonstrated power levels of up to 26 MW
in 1 us pulsed operation using a 560 kV, 95 A beam. These are record power
levels for a relativistic klystron operating at such a high frequency in pulse
lengths in the us range. An efficiency as high as 51% was achieved. Work is
continuing on optimizing the klystron performance and applying it to high
gradient acceleration experiments.
The High Gradient Accelerator Experiments Group led by Dr. Shien Chi Chen is
preparing a novel, 17 GHz microwave driven, photocathode electron injector.
This device, sometimes called an RF gun, can generate a 2 ps beam of 2-3 MeV,
50-500 A electrons at high repetition rate. A 17 GHz klystron power source
will drive the electron gun. This electron beam can be directly applied to
microwave generation experiments or it can be used as an injector into a 17
GHz, high gradient accelerator. This research supports the program to build
new electron accelerators which can reach the TeV range of energies.
The RF gun experiment has been operated with a microsecond pulse length
klystron source at power levels of 5 to 10 MW at 17.145 GHz. The power coupled
into the electron gun was monitored using the forward and reflected microwave
power. A stored field equivalent to an on-axis accelerating gradient as high as
150 MeV/m was obtained, a record high value. Work is also progressing on
generating the required laser pulse for the photocathode. This pulse must be
timed to an accuracy of 1 ps in order to coincide with the 17 GHz accelerator
field at a phase accurate to within 6 degrees.
A new research program has been initiated by Dr. Chiping Chen on the topic of
theoretical and computational investigation of periodically focused intense
charged particle beams. This research will support the U. S. program to
construct advanced accelerators for such applications as nuclear waste
treatment, heavy ion fusion and free electron lasers. Research will explore
self-field-induced nonlinear resonant and chaotic phenomena in intense charged
particle beams.
This section, led by Prof. George Bekefi, is involved in exploring the physics
of novel lasers using relativistic electron beams as the lasing medium.
Free electron laser research in this division spans wavelengths ranging from
millimeters to nanometers. At millimeter wavelengths (8.6 mm) we are generating
60MW of coherent radiation, the world's largest power at that wavelength. This
device is now being actively used in a collaborative effort with CERN/CLIC in
testing novel high gradient RF accelerating structures. The goal is to achieve
accelerating gradients in excess of 100 MeV per meter length (the SLAC RF Linac
achieves about 17 MeV/m). Since these systems are physically small, such
gradients could in principle be achieved with minimal expenditure of RF
energy.
At the opposite end of the wavelength spectrum, we are aiming at generating
tens of kilowatts of coherent radiation in the X-ray regime for use in medical
and biological studies. To this purpose we have designed, built and tested a
novel 70 period magnetic microwiggler of 8.8 mm periodicity with unprecedented
uniformity ([[ordfeminine]] 0.04%). At this level of precision, wiggler errors
are sufficiently small to allow operation at X-ray wavelengths. This program is
a collaboration with the Brookhaven National Laboratory where the MIT wiggler
is being installed on the 80 MeV, Advanced Test Facility, RF Linac. Radiation
at a wavelength of 250 nm is expected within 12 months. Achievement of this
goal would be the first of its kind in which an X-ray free electron laser is
being driven by a linear RF accelerator.
The Plasma Fusion Center is committed to increasing the number of women and
minorities at those levels of the work force where there is significant under
representation. Our success in meeting this objective is dependent on the pool
of applicants available at each level. For example, 75% of both the SRS
administrative and support staff are women, while 25% are African Americans.
In these categories, we have found that our search procedures, which utilize
both internal and external resources, have turned up an excellent supply of
highly qualified candidates. On the other hand, at the SRS technical level our
success is more modest: approximately 3.1% of SRS technical staff are women,
while 14.6% are other minorities, most of whom are Asian Americans. We are
attempting to enlarge the reservoir of qualified underrepresented applicants in
the near term by more intensive dissemination of job postings to organizations
specifically concerned with opportunities for women and other minorities and,
in the long term, with a substantial K-12 and undergraduate outreach effort
which encourages women and other minorities to pursue careers as scientists and
engineers.
The Plasma Fusion Center has established an educational outreach program
primarily focused on heightening the interest of K-12 students in scientific
and technical subjects. The Mr. Magnet Program, headed by Technical Supervisor
Paul Thomas, has been particularly successful. Mr. Magnet, with the help of a
graduate student, brings a traveling demonstration on magnetism into local
elementary schools, inspiring and exciting students with the chance to take
part in hands-on experiments with magnets. He stresses that science is a valid
pursuit for boys and girls. Over the past year he has worked with over 10,000
students. The PFC also seeks to educate students and the general public by
conducting general tours of experiments being done here. Special "Outreach
Days" are held twice a year, encouraging high school and middle school students
from around Massachusetts to visit the PFC for a day of hands-on demonstrations
and tours.
The PFC has also become involved in the Contemporary Physics Education Project
(CPEP), a collaborative effort of fusion facilities around the U.S. The goal
of this group is to create a fusion-oriented curriculum, along with supporting
hands-on experiments and graphics, for use in high schools around the country.
Mr. Paul Rivenberg has worked on the "Chart Committee" of this project, which
is focusing on creating wall charts that will aid in the understanding of
fusion.
The Fusion Forum, held each year on Capitol Hill, is a community-wide effort to
show Congress the goals of the national fusion program and its gains over the
past year. Fusion fundamentals are also outlined to educate new Congressmen
and staff members. In March 1995 Miklos Porkolab, Bruce Montgomery, Dan Cohn
and Albe Dawson, together with Tobin Smith of the MIT Washington office
participated in the Forum. An exhibit was brought to Washington to show our 1)
education and educational outreach programs, 2) Alcator C-Mod and ITER
magnetics accomplishments and 3) the PFC's plasma-science-based spin-off
technologies including hazardous waste remediation, microchip manufacture, and
cutting tool plasma-spray coatings to increase surface hardness and tool life
up to 100-fold at a very small cost increase. A videotape showing plasmas in
C-Mod received considerable attention. Bruce Montgomery testified before the
House Appropriations Subcommittee on Energy and Water, and Miklos Porkolab and
Dan Cohn made visits to several members of the Massachusetts congressional
delegation to garner their support for the fusion program. The exhibit was
selected to remain on display in the Cannon House Office building for the two
weeks following the Forum. Attendance was considerably higher than in previous
years.
During the past year, there have been several important appointments and
promotions in Plasma Fusion Center program areas:
Appointments include: Vincent Bertolino (Sullivan and Cogliano) appointed
Systems Engineer in the Alcator C-Mod Division; Changheui Jang (MIT, Nuclear
Engineer) appointed Postdoctoral Research Staff and Philip Michael (Yokohama
National University) appointed Research Engineer in the Fusion Technology and
Engineering Division; Eileen Ng (Artificial Intelligence Lab) appointed
Assistant Fiscal Officer in the Fiscal Office; Rosaria Rizzo (Earth Atmospheric
and Planetary Sciences) appointed Assistant Fiscal Officer in the Fiscal
Office; Willie Smith (Provost's Office) appointed Administrative Officer;
Robert Vibert (National Magnet Lab) appointed Assistant Fiscal Officer in the
Fiscal Office; and Randy West (Diversified Technologies Inc.) appointed
Engineer-Temporary in the Fusion Technology and Engineering Division.
Internal promotions in the Plasma Fusion Center during the past year include:
Veronica DuLong, promoted to Associate Fiscal Officer in the Fiscal Office;
Chenyu Gung, promoted to Research Engineer in the Fusion Technology and
Engineering Division; Kamal Hadidi, promoted to Research Scientist in the
Plasma Technology and Systems Division; James Irby, promoted to Head of
Operations Section of the Alcator C-Mod Division; and Pei-Wen Wang, promoted to
Research Engineer in the Fusion Technology and Engineering Division.
During the past year, there was one Institute research promotion in the Plasma
Fusion Center: Prof. Miklos Porkolab, promoted to PFC Director.
The Plasma Fusion Center has also hosted 68 Visiting Scientists, Engineers and
Scholars during the past year.
During the past year, the following students graduated with theses in plasma
fusion and related areas: Monica Blank, Ph.D., Electrical Engineering and
Computer Science; Adam Brailove, Ph.D., Physics; Michael Graf, Ph.D., Nuclear
Engineering; Carsie Hall II, M.S., Mechanical Engineering; Christian Kurz,
Ph.D., Nuclear Engineering; Chia-Liang Lin, Ph.D., Electrical Engineering and
Computer Science; Thomas Luke, Ph.D., Physics; Martin Morra, Ph.D., Material
Science and Engineering; Gennady Shvets, Ph.D., Physics; Jesus Villasenor,
Ph.D., Physics; and Ali Zolfaghari, Ph.D., Nuclear Engineering. We take this
opportunity to wish these graduates success in their future professional
endeavors.
Miklos Porkolab
MIT
Reports to the President 1994-95