Applying a novel adaptive mesh integration technique to calculate incoherent scatter spectra of non-Maxwellian plasmas

Incoherent scatter (IS) spectra fitting routines typically assume a Maxwellian ion velocity distribution to obtain estimates of plasma parameters. This is not always a valid assumption. For example, when an F-region plasma is in the presence of a strong electric field (greater than 25 mV/m), the increase in resonant charge exchange (RCE) reactions between the dominant O+ and O species can result in a non-Maxwellian ion velocity distribution that is distorted towards a toroidal shape. For such a plasma, the standard paradigm does not capture the ion temperature anisotropy. To better understand non-Maxwellian plasmas in the ionosphere from a more general sense, we develop a novel algorithm that performs adaptive mesh refinement to account for the poles in the integrals used to calculate IS spectra. The parallel velocity mesh is refined symmetrically about each pole and the distribution function is linearly interpolated onto the refined mesh before using trapezoidal integration to perform the calculations. This algorithm is well benchmarked to known analytical solutions for Maxwellian ions and electrons. Initial results are provided for a plasma with toroidal ions and Maxwellian electrons. These results will help in obtaining better estimates of the O+-O RCE collision cross-section as well as provide an understanding of the error associated with assuming a fully Maxwellian plasma in traditional IS spectra calculations.