TFTR Plasma Discharge

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. Scientists at the Princeton Plasma Physics Laboratory recently discovered a new plasma confinement regime. By decreasing the influx of neutral gas from the walls of the vacuum chamber containing the plasma, they obtained peak plasma density profiles and high ion temperatures. This led to a reduction in energy loss by a factor of two to three and an increase in the number of thermonuclear fusion reactions by a factor of about 20. Scientists later used this enhanced confinement regime to produce 10.7 million watts of fusion power, with a total yield of 4.2 million joules, in a deuterium-tritium plasma. (A deuterium-tritium fusion reaction produces a neutron and an alpha particle [helium-4 nucleus], while mass is converted to energy. The neutron carries away 80 percent of this energy, and the rest goes to the alpha particle. In a fusion power plant, the neutron energy would be converted to heat to make steam for the generation of electricity; the alpha particle energy is transferred to the plasma and, when sufficient to sustain the plasma temperature, the plasma is "ignited.") Three scientists won the American Physical Society Award for Excellence in Plasma Physics Research in 1988.

Scientific Impact: The enhanced confinement regime was used to study the confinement of fusion-produced alpha particles. The scientists determined that alpha particle confinement and loss agreed with theoretical predictions, and they observed the first indications of alpha particle heating of the background plasma.

Social Impact: This advance helped lay the groundwork for promoting fusion as an attractive energy source. If converted to electricity, the 10.7 million watts of fusion power produced in this experiment would meet the needs of about 3,000 average-sized homes.

Reference: "High Temperature Plasmas in a Tokamak Fusion Test Reactor," J. D. Strachan, M. Bitter, A. T. Ramsey, ..., Phys. Rev. Lett. 58, 1004 (1987).

"Fusion Plasma Experiments on TFTR: A 20-year Retrospective," R. J. Hawryluk, S. Batha, W. Blanchard, M. Beer, ..., Phys. Plasmas 5, 1577 (1998).

URL: http://www.pppl.gov/projects/pages/tftr.html

Technical Contact: Steve Eckstrand, Research Division, 301-903-5546

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of Fusion Energy Sciences