Simulations of the ion current to a probe in plasma with allowance for ionization and ion-neutral collisions: I. Spherical probe

Abstract

The ion current to a spherical probe is considered with allowance for volume ionization, ion-neutral collisions, and the ion orbital moment. A model based on the molecular dynamics method and applicable for a wide range of plasma parameters is proposed: rp/λD = 0.001–100, λi/λD = 0.001–100, \({{\nu _i \lambda _D } \mathord{\left/ {\vphantom {{\nu _i \lambda _D } {\sqrt {{{kT_e } \mathord{\left/ {\vphantom {{kT_e } M}} \right. \kern-\nulldelimiterspace} M}} }}} \right. \kern-\nulldelimiterspace} {\sqrt {{{kT_e } \mathord{\left/ {\vphantom {{kT_e } M}} \right. \kern-\nulldelimiterspace} M}} }} = 0.01 - 1\), and Ti/Te = 0.01. A convenient representation of the dependences of the relative ion current density on the Langmuir coefficient α2 and a technique for determining the plasma density from simulation results are offered.