12 research outputs found
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Mirror machine program in the USA
As the result of recent experimental progress, theoretical advances, and the emergence of new approaches to the improvement of mirror confinement, the mirror approach has become the principal alternative to the tokamak in the USA magnetic fusion program. Emphasis is now centered on the Tandem Mirror and Field-reversed Mirror Concepts, which theoretically can obtain Q values of five or more. Recent progress in the mirror fusion program includes a series of favorable advances in the 2XIIB experiment and the development of a theoretical model that accounts for observed plasma behavior in 2XIIB and other mirror experiments. This theory provides scaling laws for extrapolating of present experiments to larger devices. These advances, together with the emergence of new approaches to the improvement of mirror confinement, have led to increased planning and construction of magnetic mirror systems in the USA. The USA mirror program is shown including several university experiments
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2XIIB plasma confinement experiments
This paper discusses results of plasma-confinement experiments in the 2XIIB magnetic mirror device. We report experiments attempting to achieve field-reversal using neutral-beam injection in which the central magnetic field is reduced by 90% but field lines are not closed. Experiments with different neutral-beam aiming show that at constant beta both electron temperature and the energy-confinement parameter (n tau) increase at larger radius. Finally, we discuss recent improvements in electron temperature and microinstability measurements
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Directions for possible upgrades of the Mirror Fusion Test Facility (MFTF)
The Mirror Fusion Test Facility (MFTF) may be upgraded by extending the time of plasma sustenance in an approach to steady-state operation and/or by increasing the neutral-beam injection energy. Some parameter bounds for these upgrades are discussed as they relate to a definition of the required neutral-beam development
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A high-fluence fusion neutron source
A conceptual design of a D-T fusion facility for continuous production of 14-MeV neutron wall loading from 5 to 10 MW/m/sup 2/ at the plasma surface is presented. In this design, D-T neutrons are produced in a linear, two-component plasma formed by neutral beam irradiation of a fully ionized warm plasma target. The beam energy, which is deposited in the center, is transferred to the warm plasma mainly by electron drag and is conducted along the target plasma column to end regions where it is absorbed in neutral gas at high pressure. The target plasma is operated in a regime where electron thermal conduction along the column is the controlling energy-loss process. The loss rate is minimized by adjusting the diameter and length of the plasma column. A substantial gradient in T/sub e/ along the column results in recombination of the plasma to gas in the end-regions before impact on the end walls. The resultant hot gas is cooled by contact with large-area heat exchangers. In this way, the large steady-state heat load from the injected neutral beams is diffused and removed at tolerable heat flux levels. The reacting plasma is essentially an extrapolation of the 2XIIB high-..beta.. plasma to higher magnetic field, ion energy, and density. 12 refs., 4 figs
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Microwave measurements of 2XII radial and longitudinal electron density profiles.
Initial TMX-U thermal-barrier experiments
This paper describes results from the initial thermal barrier experiments in the Tandem Mirror Experiment-Upgrade (TMX-U). Strong end plugging has been produced using a combination of ECRH gyrotrons with sloshing ion beam injection. Plugging has been achieved with a central cell higher than that of the end plugs. In these low-density central cell experiments (7 x 10/sup 11/ cm/sup -3/) the axial losses (tau/sub parallel to/ = 20 to 80 ms) are smaller than the radial losses (tau/sub perpendicular to/ = 4 to 8 ms). Although no direct measurements are yet available to determine if a thermal barrier potential dip is generated, these experiments support many theoretical features of the thermal barrier concept