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Background
The Physics Research Division, headed by
Professor Miklos Porkolab, seeks to improve
our theoretical and experimental understanding
of plasma physics and fusion science.
This Division develops basic plasma physics experiments,
new confinement concepts, novel
plasma diagnostics, and is the home of a strong
basic and applied plasma theory and computations
program. Members of the Physics Research
Division include theoretical and experimental
plasma physicists, faculty members, graduate and
undergraduate students and visiting collaborators,
all working together to better understand
plasmas and to extend their uses.
Recent Research Activities
Fusion Theory and Computation
The theory effort, led by Senior Research Scientist
Dr. Peter Catto, focuses on basic and applied fusion
plasma theory research. It supports Alcator C-
Mod and other tokamak experiments worldwide,
the Levitated Dipole Experiment (LDX), and the
international stellarator program. In support of
these efforts, PSFC theorists are developing improved
analytical and numerical models to better
describe plasma phenomena, both in the laboratory
and in nature. In addition to basic plasma
theory, research on radio-frequency heating and
current drive, core and edge transport and turbulence,
and magnetohydrodynamic (MHD) and
kinetic stability is also carried out. PSFC theorists
also investigate concepts to improve tokamak
performance.
One promising approach to advanced tokamak
operation uses radio-frequency waves to control
pressure and current profiles in order to heat, control
instabilities, and achieve steady state operation
in high-pressure plasmas. Recently we have
further improved our advanced kinetic codes for
simulating the resulting non-thermal particle distributions
in the lower hybrid and ion cyclotron
range of frequencies, as well as carried out validation
activities aimed at testing the predictive
capabilities of these models, in close collaboration
with experimentalists. We have improved our
ability to model the non-thermal tail part of the
ion distribution function that is generated by the
wave heating, and have also improved the electron-physics
model. Moreover, the performance of
these codes has been substantially enhanced. An
example of this enhanced simulation capability,
shown here, illustrates a three-dimensional field
reconstruction of lower-hybrid-range-of-frequency
(LHRF) waves in the Alcator C-Mod tokamak.
The wave fields can be seen emanating from four
waveguides and propagating toroidally, with the
characteristic resonance cone structure expected
for LH waves. We also performed theoretical investigations
of the scattering of radio-frequency
waves from edge-density fluctuations and density
blobs in the scrape-off layer of tokamak plasmas,
and derived a new kinetic formulation of radiofrequency-induced
current drive in high-temperature
toroidal fusion plasmas. In addition, a new
nonlinear sheath theoretical and computational
model has been developed to describe the sheath
regions associated with the antennas. (“Sheaths”
are regions of non-neutral plasmas in the vicinity
of metallic surfaces.)
Another active arc of research is nonlinear MHD
theory and its impact on stability and transport.
In the past two years we have made major prog-
Three dimensional rendering of TORLH simulations of LHRF using selfconsistent
electrons in an Alcator C-Mod plasma [T e
(0) = 2.33 keV, n e
(0) =
7×10 19 m -3 , B 0
= 5.36 T, n ||
(0) = -1.9 and 0
= 4.6 GHz].
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