Impact of azimuthal forcing on the Brillouin limit in a collisional two-species Ohkawa filter
Impact d'un forçage azimuthal sur la limite de Brillouin dans un filtre d'Ohkawa à deux espèces
Résumé
This paper investigates the Brillouin limit in a two species rotating collisional plasma, when the source of rotation is an orbital angular momentum carrying wave. The electric field is treated self-consistently with ion and electron radial motion. The injection of angular momentum causes radial currents leading to charge penetration and electric field build up. The electric field varies until an equilibrium with the friction forces is reached. Both collisions with neutrals and Coulomb collisions are considered. In this context, there is no collisional breakdown of the Brillouin limit, on the contrary the maximum achievable electric field decreases when the collision frequency is increased. When two species are present, one that undergoes the forcing while the second is passive, the first species is confined, while the second species can be expelled or confined depending on the charge to mass ratio and the collisionalities. Assuming equal charge numbers, if the second species is the heavy one, it is always expelled, which is a standard result. When the second species is the light one, it can also be expelled in the common case where neutral collisions dominate over Coulomb collisions, which constitutes a new result.
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