Lower hybrid current drive accessibility study with reconstructed magnetic equilibria in PBX-M

Ray tracing simulations based on experimental PBX-M equilibria show a limited range of the parallel wavenumber (n_||=k_||c/ ω) along a ray trajectory. The range of n_|| accessible to the excited wave is shown to have both a lower and an upper bound. The ray's phase volume is projected into (n_||, R, Z) space to define a domain of wave accessibility for each toroidal mode number excited by the launcher. A comparison of circular and bean shaped plasmas with a high aspect ratio (A ∼ 5.5) shows that the rays fill a substantially larger portion of the accessible domain in bean shaped plasmas. Furthermore, in the bean shaped case the accessible domain tends to extend to higher n_||.