Magneto-hydrodynamically stable axisymmetric mirrors

Abstract

Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.

Global sound modes in mirror traps with anisotropic pressure

“…Typical plasma parameters in relevant regimes range from n ¼ 1 À 5 Â 10 21 m À3 ; T i ¼ 1 À 2 keV; T e ¼ 150 eV in GOL-3, to n ¼ 1 À 3 Â 10 19 m À3 ; T i $ 5 keV; T e ¼ 150 À250 eV in GDT. 2,3 The frequency spectrum is sharply peaked, essentially discreet. Wave phases at ends of mirror cells are opposite, while the angular wave-numbers may vary, but the zero mode is most common.…”

A phenomenological model on the kink mode threshold varying with the inclination of sheath boundary

“…Similarly, a LT BC is also taken for granted in a linear fusion device such as tandem mirror with kinetic stabilizer, in which the field lines flare out to make favorable magnetic curvature. 26 It is worth pointing out different curvature may also change the angle of flared-out field lines to the endplate and thus change the plasma stability.…”

Plasma Mass Filters For Nuclear Waste Reprocessing

“…Sheared rotation is the most common way of stabilizing a rotating plasma [29,30]. On the other hand, the plasma may be stabilized by other effects like the large orbits of heavy particles or by escaping particles, or it may be possible to use newly proposed stabilization methods [31,32].…”