Particle simulations of transport in a high-recycling divertor scrape-off layer

Summary form only given. The transport of particles and energy through a tokamak scrape-off layer (SOL,) was studied via the particle simulation code DIPSI (Direct Implicit Plasma Surface Interactions). This code combines direct-implicit particle-in-cell (PIC) techniques with Monte Carlo models for Coulomb collisions and charged/neutral atomic physics interactions. Recycled neutral particles are treated in an ad hoc manner: the density is assumed to decay exponentially with increasing distance from the divertor plate and the temperature of the neutrals is prescribed by the user. The neutral particles interact with the background plasma via charge-exchange events with ions and impact ionization events arising from electron/neutral collisions. This model is used to determine the effect of charged/neutral interactions on the transport properties of a tokamak SOL plasma. The prescribed neutral particle density will span a wide range of recycling fractions. Values of the presheath and collector sheath potential drops, plasma temperature, flow velocity, and parallel heat fluxes were obtained as a function of charged/neutral collisionality