Effect of parallel magnetic field gradients on absorption and mode conversion in the ion-cyclotron range of frequencies

The nonlocal Vlasov-Maxwell dielectric response kernel, K(r,r’), is constructed by integration along particle orbits in a nonuniform magnetic field. The phase integrals comprising the usual plasma dispersion function are altered, and contain a parameter characterizing the parallel field gradient. We numerically solve a 1D integral wave equation, including a parallel field gradient, describing the propagation, mode conversion, and absorption physics. Significant changes in absorption are found for the small-${\mathit{k}}_{\mathrm{\parallel }}$ regime.