Nonlinear fluctuation-dissipation theorem for plasma in case of nonpotential field

Considered are linear and nonlinear responses to the external exciting nonpotential field in plasma. It is shown that additional correlations exist which bind correlation functions for current fluctuations of a higher order with nonlinear susceptibilities, apart from the ordinary fluctuation-dissipation correlation which binds the quadratic correlation function for the fluctuations of current density with the tensor of linear electric susceptibility