$\alpha$ Channeling in a Rotating Plasma

The wave-particle $\alpha$-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with $\alpha$ particles in a mirror machine with $E\times B$ rotation to diffuse the $\alpha$ particles along constrained paths in phase space. Of major interest is that the $\alpha$-particle energy, in addition to amplifying the rf waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity.

Figure 1

The loss cone in (rotating) midplane energy coordinates for a rotating plasma, including centrifugal confinement.

Figure 2

The shaded region indicates the wave resonance, dependent on radius. The dashed lines depict diffusion paths that would eject particles using only perpendicular diffusion. Path (a) reduces both the kinetic and potential energy of the particle, path (b) increases potential energy but decreases kinetic energy, and path (c) increases both kinetic and potential energy. The energy balance is assumed by the wave.

Figure 3

Channeled energy (blue circles) and extraction time (purple squares) versus birth pitch angle.