Trace impurity transport in tokamaks is studied using an electrostatic, collisionless fluid model for ion-temperature-gradient and trapped-electron mode driven turbulence in the presence of radio frequency (rf) fields, and the results are compared with neoclassical predictions. It is shown that the inward impurity convective velocity (pinch) that is usually obtained can be reduced by the rf fields, in particular close to the wave resonance location where the rf ponderomotive force may be significant. However, the impurity diffusivity and convective velocity are usually similarly affected by the ponderomotive force, and hence the steady-state impurity density peaking factor −∇nz∕nz is only moderately affected by the rf fields.
The field emission from negatively charged spherical solid particles has been studied analytically, and some numerical results depicting the variation in the number of emitted electrons with the charge, radius and work function of the particle are presented.
We investigate the effect of self-consistent dust charge fluctuations on collective modes in an inhomogeneous magnetized dusty plasma. A fluid model is developed where the dust dynamics and the charge fluctuations are taken into account. It is shown that for the Rayleigh-Taylor mode both dust dynamics and charge fluctuations lead to a rapid increase of the stable regime. It is also shown that charge fluctuations can drive the drift wave unstable under certain conditions that are relevant to some astrophysical situations.
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