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 fo r the statistical distribution of the suprathermal particles, the kapp a velocity distribution is used. It is found that the Debye length lam bda(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 part icle discreteness more important. than for a Maxwellian plasma. Conseq uently levels of fluctuation are higher, and their extent in wavenumbe r and frequency greater, in plasmas containing suprathermals. Results for a number of different 'concentrations' of suprathermal particles a re discussed and interpreted in terms of the normal- as well as transi ent-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 ka ppa(e) much greater than kappa(i), are investigated.