Plasma confinement by circularly polarized electromagnetic field in toroidal geometry

Abstract

A novel plasma confinement concept based on plasma confinement by electromagnetic pressure of circularly polarized electromagnetic fields is proposed. Practical implementation of this concept in a toroidal device is suggested. In this concept the confining field frequency is in the lower range such that the size of the device is much smaller than the vacuum wavelength. Most of the previous radio-frequency (rf) confinement concepts of unmagnetized plasma were related to confinement in rf cavities which operated at high frequency for which the size of the cavity is comparable to the wavelength. Operation at lower frequencies simplifies rf design, reduces Ohmic losses in the conducting walls and probably makes application of superconductors for wall materials more feasible. It is demonstrated that circular (or nearly circular) polarization of the electromagnetic field is required for confinement from both the equilibrium and stability considerations. Numerical analysis of plasma confinement for magnetohydrodynamic plasma model in two-dimensional toroidal geometry is performed. Within this model plasma is confined by the applied rf fields and its equilibrium is stable. Technically feasible compact and medium size toroidal plasma confinement devices based on this concept are proposed. Application of this approach to the fusion reactor requires use of superconducting materials for the toroidal shell to reduce the Ohmic losses. Further theoretical and experimental studies are required for a more reliable conclusion about the attractiveness of this plasma confinement concept.