Parametric Decay of "Kinetic Alfvén Wave" and Its Application to Plasma Heating

Abstract

Because of its electrostatic properties, the rate of the parametric growth of the kinetic Alfv\'en wave [Alfv\'en wave with $\ensuremath{\lambda}\ensuremath{\equiv}\frac{{{k}_{\ensuremath{\perp}}}^{2}{{c}_{s}}^{2}}{{{\ensuremath{\omega}}_{\mathrm{ci}}}^{2}}\ensuremath{\sim}O(1)$] is shown to be larger than that of the classic result by a factor of $\frac{\ensuremath{\lambda}{\ensuremath{\omega}}_{\mathrm{ci}}}{{\ensuremath{\omega}}_{\mathrm{A}}}$, where ${\ensuremath{\omega}}_{\mathrm{ci}}$ and ${\ensuremath{\omega}}_{\mathrm{A}}$ are the ion-cyclotron and the Alfv\'en frequencies, ${k}_{\ensuremath{\perp}}$ is the perpendicular wave number, and ${c}_{s}$ is the ion sound speed. This fact can be utilized to heat a plasma with typical tokamak parameters.