Molecule Assisted Recombination (MAR): Mechanisms and Plasma Conditions for Effective Operation

The main features of plasma and neutral gas recycling at the edge of magnetic confinement devices are discussed and the crucial impact of plasma volumetric recombination on power load on material surfaces is demonstrated. The physics of molecular assisted recombination (MAR) involving ro-vibrationally excited molecular hydrogen is discussed. It is shown that although conventional electron-ion recombination (EIR) alone can strongly alter edge plasma parameters, MAR may even exceed the impact of EIR for magnetic confinement devices. However, unlike EIR, the MAR crucially depends on recycling of the molecules on the wall surface and, therefore, the MAR efficiency can be sensitive to geometrical effects.