Effect of charge fluctuations and collisions on the energy loss of NxM projectiles for a generalized Lorentzian dusty plasma

The shielded potential and the energy loss by NxM projectiles passing through a collisional dust-contaminated plasma with dust-charge fluctuations and grain-size distribution are presented. Analytical general expressions are obtained for the shielded potential and for the energy loss by considering two-body correlation effects. An interference contribution of these projectiles to the potential and energy loss is observed which depends upon their orientation and separation distance. The dust-charge fluctuation produces a potential well instead of Coulomb-type potential for a slowly moving test charge with slow charge relaxation rate and energy is gained by the charged projectiles. However, fast charge relaxation enhances the energy loss and some peaks are observed showing the excitation of some electrostatic modes. On the other hand, the dust neutral collisions also enhance the energy loss for projectile velocities greater than the dust acoustic speed for a Maxwellian plasma (for a large value of the spectral index κ)