The Effects of a D.C. Electric Field on the Current Driven Ion Cyclotron Instability.

A nonlocal kinetic formalism will study the electrostatic ion waves that can be excited in a magnetised plasma including a d.c. electric field such as a double layer. The d.c. electric field can have components parallel and perpendicular to the uniform ambient magnetic field. In a collisional plasma, E parallel can give rise to a magnetic field aligned drift V sub d of the electrons with respect to the ions, while E perpendicular provides an E perpendicular X B drift to both the species. For V sub d 0, our formalism recovers the ion cyclotron like modes, while for E perpendicular 0, the ion cyclotron modes . The electrostatic ion modes are studied for arbitrary values of V sub d and E perpendicular. It is found the the real frequency is strongly affected by the transverse component of the d.c. electric field and can assume values much different from the harmonics and may even get below the first harmonic. The growth rate is influenced by the field aligned electron drift. Keywords Ion waves Instability Nonlocal Electric field.