Ion Loss by Collisions Outside the Core

In this note, we extend the calculation of ion loss due to collisional upscattering in the core of the Polywell/SCIF device to include effects of ion-ion scattering in the rest of the device. As the ions transit through the device, collisional processes, such as upscatter or deflection, can alter their velocity distributions, leading to Maxwellization of initially monoenergetic distributions, or isotropization of initially anisotropic distributions. These effects can contribute to ion loss mechanisms. We consider the effects of ion-ion collisions outside the core and estimate the loss rates due to associated loss mechanisms. We consider the scattering in azimuthal velocity of ions in the bulk of the device, where the radial ion energies are much larger than the azimuthal energies. Perpendicular deflection and conversion of radial to azimuthal velocity by collisions could lead to a degradation of the ion focus. We also consider the effects of thermalization in the edge region of the device, where the ion energy is low and of the order of the ion birth energy.