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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
energy source in the future. A key
to developing a fusion energy source
is the formation and maintenance of
the complex magnetic fields that confine
the plasma. In a tokamak device, a
toroidal current in the plasma is
a critical component of the magnetic
field. In the 1970s, physicists proposed
that the pressure gradient in fusion
plasma gives rise to a powerful "bootstrap
current." This prediction was confirmed
in the 1980s, and the bootstrap current
was demonstrated at fusion-relevant
temperatures in excess of 100,000,000
°C at Princeton Plasma Physics Laboratory.
In addition, with Office of Science
support, theorists at the Massachusetts
Institute of Technology predicted
that radio-frequency electromagnetic
waves could produce a net flow of
electrons in a tokamak—similar
to surfers being moved by a wave—thereby
generating a strong current efficiently
enough to be useful in a fusion power
plant. This research was verified
by experiments in Japan and the United
States. For this work, researchers
from both countries, including scientists
from MIT and PPPL, won the American
Physical Society Excellence in Plasma
Physics Research Award in 1984.
Scientific Impact:
This work extended earlier pioneering
research on the natural symmetry between
thermodynamic forces and the particle
fluxes they support, and on wave-particle
interactions. It is now possible to
maintain and control the magnetic
field profile in an advanced tokamak
configuration with a combination of
bootstrap and radio-frequency wave
drive currents.
Social Impact: These
advances 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: "Theory
of Current Drive in Plasmas," Nathaniel
J. Fisch, Rev. Mod. Phys.
59, 175 (1987)
"Bootstrap Current in TFTR," M. C.
Zarnstorff, M. G. Bell, M. Bitter,
..., Phys. Rev. Lett. 60,
1306 (1988)
URL:
http://www.pppl.gov/projects/pages/tftr_achievements.html
Technical Contact:
Curt Bolton, Research Division, 301-903-4914
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Fusion Energy Sciences |
