2025/08/12 by Alessandro Geraldini, Robert J. Ewart, Geraldini, Alessandro +4
Physics and Astronomy · Materials Science · #Magnetic confinement fusion research #Fusion materials and technologies #Fusion and Plasma Physics Studies
paper · pdf · doi:10.48550/arxiv.2508.09067
We consider a magnetised plasma in contact with an absorbing planar wall, where the angle α between the magnetic field and the wall is small, α≪ 1 (in radians) and the system is symmetric tangential to the wall. The finite ratio γ of the characteristic electron gyroradius ρ\rm e to the Debye length λ\rm D, γ= ρ\rm e / λ\rm D, is retained via a grazing-incidence (α≪ 1) gyrokinetic treatment [1,2]. Building on a previously developed iterative scheme [2,3] to solve for the steady-state electrostatic potential in the quasineutral magnetic presheath of width ∼ ρ\rm S, we developed a scheme that simultaneously solves for both the presheath and the non-neutral Debye sheath of width ∼ λ\rm D in the limit λ\rm D / ρ\rm S → 0. The code, called GYRAZE, thus provides the energy-angle distribution of ions at the wall and the velocity distributions of electrons reflected by the wall for different values of wall potential. A monotonic electrostatic potential profile, assumed in this work, can only exist for magnetic field angles larger than a critical value [3]. While the critical angle is shown here to significantly increase with γ, it is still typically smaller than the magnetic field angle at divertor targets of a fusion device.