Electrostatic fluctuations in plasmas containing suprathermal particles

The spectral density of electrostatic fluctuations is investigated in a plasma containing an excess of suprathermal particles. As a model for the statistical distribution of the suprathermal particles, the kappa velocity distribution is used. It is found that the Debye length lambda(D) for such a plasma depends strongly on the spectral index kappa of the velocity distribution, and can be much smaller than is commonly found for Maxwellian plasmas. Consequently the plasma parameter g = 1/n lambda(D)(3) call be larger, and plasma effects that depend on particle discreteness more important. than for a Maxwellian plasma. Consequently levels of fluctuation are higher, and their extent in wavenumber and frequency greater, in plasmas containing suprathermals. Results for a number of different 'concentrations' of suprathermal particles are discussed and interpreted in terms of the normal- as well as transient-mode behaviour of the plasma. Both the cases T-e much greater than T-i and T-e = T-i, as well as kappa(e) much less than kappa(i) and kappa(e) much greater than kappa(i), are investigated.