Theory and observations of ion energization in the presence of large amplitude ion cyclotron waves and a DC electric field in a weakly ionized plasma

Summary form only given, as follows. Recently, a series of experiments conducted in the Naval Research Laboratory´s Space Physics Simulation Chamber (SPSC) have shown ion energization in a weakly ionized argon plasma in the presence of large amplitude ion cyclotron waves and a DC electric field. The SPSC is a 1.8 m diameter by 5 m long cylinder equipped with a microwave discharge plasma source, an external magnetic field, and a variable background pressure. Wave and bulk parameters are measured with heatable Langmuir probes, emissive probes, and a perpendicular ion energy analyzer. DC electric fields are created within the SPSC plasma column by modifying the plasma potential tranverse to the external magnetic field. The experimental observations indicate that the argon ion perpendicular temperature can be increased at least by a factor of 2 in the presence of 1-10% plasma density fluctuations, a inhomogeneous DC electric field, and large amplitude ion cyclotron fluctuations. The ion collision frequency is composed of both ion-neutral and ion-electron contributions and can be varied to be much less than or greater than the ambient ion cyclotron frequency. We have computed the expected ion energization in the SPSC using several approaches, i.e., particle-in-cell simulations, quasilinear heating, large amplitude trapping, and ion collisional heating. We will present the results of these analyses and compare with the experimental observations.