Beam production at plasma boundaries by kinetic Alfvén waves

Wave‐induced transport can produce diffusion both in coordinate space and in velocity space with transport rates which are much closer than the corresponding rates for classical transport. In such a case the quasi‐linear diffusion in velocity space should be solved in conjunction with the diffusion in coordinate space. This leads to processes hitherto unknown, such as the generation of a large number of accelerated particles near the plasma‐vacuum boundary. As an example, the theory of a double diffusion caused by kinetic Alfvén wave turbulence is presented, and generation of ion beams is discussed.