Restructuring of rotating spokes in response to changes in the radial electric field and the neutral pressure of a cylindrical magnetron plasma

Nonlinear plasma structures in the partially magnetized E×B of a cylindrical magnetron are investigated using 2D3V particle-in-cell Monte Carlo collision simulations. In early phase discharge, gradients and radial electric fields excite lower hybrid type instability that forms long wavelength rotating density spokes. As discharge grows by ionization cathode gets shielded formation an ion sheath, diminish quasineutral region discharge. This induces transition spokes into short-scale spoke-on-spoke modes. The short can be reversed back spiral spoke lowering neutral pressure, which revives via turbulent expansion. Plasma phenomena connected to include anomalous transport loss electrons through spoke, azimuthal dragging ions spoke’s field, temperature modulations structure, electron vortices around equipotential islands, some cases with opposing rotations underlying drift. Electron scattering from non-ionizing collisions neutrals also has minor influence on instability.