Freshly created ions can be picked up by a moving plasma without relying on collisions. It is well known that such an ion pickup process can be accomplished via the interaction with Alfvén waves. However, it should be stressed that in general ion pickup is attributed to two distinctly different sub-processes, namely, pitch-angle diffusion and pitch-angle scattering. In this article their difference is discussed and furthermore, some new results from a recent theoretical study are reported. It is found that under some conditions the usual quasilinear theory which describes the pitch-angle diffusion process cannot be justified even when the turbulence level is low. Another significant finding is that in the presence of strong Alfvén turbulence, thermal ions can be intensely heated by a nonlinear damping of the waves, which does not depend upon the usual ion cyclotron resonance.

The online version of the original article can be found at http:// dx

The online version of the original article can be found at http:// dx.

Abstract. This paper discusses an instability of extraordinary Bernstein waves, driven by a beam of energetic electrons. The present research is motivated by the study of solar radio emission processes, and its findings may have interesting implications. Specifically, the extraordinary Bernstein waves excited both below and above the plasma frequency by the present instability can, in principle, mode convert to either of the free-space propagating modes in the presence of magnetic field and/or density inhomogeneities. This paper is devoted to an analysis of the basic properties associated with the present instability over a wide range of various physical parameters.

Various gyrokinetic simulations suggest that the kinetic ballooning mode (KBM) instability is sensitive to the numerical implementation of equilibrium magnetic configuration in tokamaks. In this work, the gyrokinetic code GTC is employed to investigate the KBM's sensitivity to equilibrium plasma profiles. An outward radial shift of the radial mode is found for the normal magnetic shear case, but there is no shift if the shear is negative. The simulation results are explained by a linear eigenmode theory. It is found that the observed phenomenon is an effect of the parallel ion compressibility.

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