Electronegative plasma-sheath characteristics over a wide range of collisionality

The non-neutral sheath region of a collisional electronegative discharge is investigated. It is assumed that the colli-sion cross section have a power law dependence on the positive ion velocity. The effects of dependency of the cross section on the velocity on the profile of the positive ion velocity and electric potential are obtained. In addition, the effects of negative ion temperature and negative ion concentration on the positive ion velocity and electric potential are investigated for different values of power factor and collision amplitude of the cross section. It is shown that, the presence of the collisions leads to the diminishing the sheath thickness and the influence of the power factor is more pronounce in higher collision amplitude.