Electrostatic Orbitron Fusion Reactor: Particle-in-Cell Plasma Density and Power Balance Simulations

In this paper, we explore using a fully kinetic Particle-in-Cell code WarpX [1] to model ion and electron Coulomb collisions and momentum transfer in a potential well with an axial magnetic field. This unique configuration of plasma confinement is referred to as an “Orbitron” type configuration. The Orbitron is a “crossed-field” device that attempts to achieve a useful fusion plasma triple product (confinement time, density, energy) by confining high-energy ions electrostatically for long duration orbits around a cathode, as is the case in an Orbitrap, while confining electrons in an E×B weak magnetic field, like a Magnetron. The confined electrons mitigate electrostatic ion space-charge density constraints, enabling a high density of ions orbiting with trajectories and energies sufficient for ion-ion fusion. We apply the WarpX PIC code developed by Lawrence Berkeley National Lab along with fully kinetic collision models for ion-ion, ion-electron and electron-electron collisions to assess the achievable plasma density and plasma loss mechanisms. The results of the PIC code are compared to a first-order model to assess the plasma power balance physics. We find that for deuterium-tritium fuels, taking into account Coulomb collisions and Bremsstrahlung X-ray losses, a plasma Q > 1 (Power Out / Power In) may be possible.