Development of Coulomb Collision Operator for Multi-Ion Species Plasmas

Understanding the interactions of multi-ion species is essential for analyzing particle transport in divertor plasmas. This study focuses on the development of a Coulomb collision operator utilizing the Nanbu collision algorithm for modeling Coulomb interactions among multi-ion plasmas composed of hydrogen isotope ions and electrons. Simulations initialized with a Maxwellian velocity distribution examine the energy relaxations and momentum exchanges among particle species. The simulation results confirm energy conservation and reveal energy relaxation patterns, with equilibrium timescales influenced by interspecies mass differences. Incorporating particles with unequal statistical weights improves computational efficiency, reducing simulation time while maintaining the accuracy of these relaxation dynamics. This approach accelerates the Coulomb interactions in multi-ion species plasmas, making it an effective tool in fusion plasma research.