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Helicon
Plasma |
Plasma science (the study of ionized
gases) is critical to the development
of fusion energy (involving the fusion
of nuclei), which could be an abundant
and attractive energy source in the
future. An important parameter in
plasma science is the current density
profile, which is fundamental to the
equilibrium, stability, and transport
of particles and heat in plasma. Fusion
Physics & Technology, Inc., a small
business, used DOE funding to develop
a technique for measuring the internal
magnetic field in fusion plasmas,
thus making it possible to determine
the current distribution. This technique
uses a beam of neutral atoms that
propagates across the magnetic field
in fusion plasma. The resulting electric
field causes a wavelength splitting
and linear polarization of the radiation
emitted by the beam atoms that are
excited by collisions with background
gas. The direction of polarization
indicates the magnetic field pitch
angle, from which scientists can compute
the plasma current density profile.
This measurement technique was first
implemented at the Princeton Plasma
Physics Laboratory. The principal
investigator, Fred Levinton, received
the American Physics Society Award
for Excellence in Plasma Physics Research
in 1997 for this pioneering work.
Scientific Impact:
Results of measurements made with
this technique have made important
contributions to understanding of
the physics of plasmas, especially
heat and particle transport, and have
provided a basis for comparison with
theory. The technique has become widely
accepted, and similar instruments
are operating on many fusion experiments
around the world.
Social Impact: This
innovation will help promote the availability
of fusion as an inexhaustible, safe,
and environmentally attractive energy
source. In addition to the general
public, beneficiaries may include
industries that use plasma science
and technology, including makers of
semiconductors and space propulsion
systems.
Reference: "Magnetic
Field Pitch-Angle Measurements in
the PBX.M Tokamak Using the Motional
Stark Effect," F. M. Levinton, R.
J. Fonck, G. M. Gammel, R. Kaita,
..., Phys. Rev. Lett. 63,
2060 (1989)
URL:
http://w3.pppl.gov/tftr/overview/mse.html
Technical Contact:
Darlene Markevich, Research Division,
301-903-4920
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Fusion Energy Sciences |