Screening and electric double layer in strongly coupled plasmas

Summary form only given. The screening in strongly coupled (nonideal) plasmas is studied using the molecular dynamics simulations. The length and settling time of the electric double layer in a plasma-vacuum interface are obtained. Interaction of strong microwave or laser irradiation with metal surfaces leads to ionization and creation of plasmas. In the case of high plasma density (n_e ~ 10¹⁹-10²¹cm^-3) and relatively low temperature (T~1eV) the plasma becomes strongly coupled and cannot be treated using the classical plasma theory. Such plasma plays essential role in the near cathode processes of high electric gradient vacuum devices. It is also responsible for laser energy deposition and initial relaxation processes in the experiments with femtosecond laser pulses irradiating cluster or bulk materials. The screening length is one of the major plasma proper ties which determines the dynamical response function, plasma microfields, external field penetration, the electric double layer structure, etc. However, the Debye approximation which comes from the ideal plasma theory is not applicable for the plasmas mentioned above. In this work the nonequilibrium molecular dynamics simulations are applied to study both the relaxation rate and the steady state of the double layer structures at plasma nonuniformities. Moreover the screening length in the bulk equilibrium plasma is obtained as a dependence on the plasma nonideality parameter.