Paper detail

Coherent effects in the stochastic electrodynamics of two-fluid plasma

Random electromagnetic fields are ubiquitous in plasmas, the most common example being electromagnetic radiation of thermal origin. They should exert a random force on electrons and ions in a plasma, adding a random component to their motion. Products of randomly fluctuating quantities, such as velocity and magnetic field, which are correlated through the dynamical equations of the two-fluid model of plasma, should then exhibit non-zero average values. Investigation of such effects requires spatial-spectral representation of the non-linear equations of the two-fluid model. Chandrasekhar-Kendall (CK) functions, their generating function and its gradient defined over an infinite domain are shown to simultaneously provide orthogonal basis for solenoidal, scalar and irrotational fields respectively, facilitating transformation from coordinate space to mode number space and back. This paper constructs a theoretical framework for studying coherent effects of random forces due to random electromagnetic fields in a two-fluid plasma and discusses some results which follow from its structure. Azimuthally symmetric modes are shown to be the sole beneficiaries of the cooperation of random modes in generating non-random effects. The formalism also facilitates investigation of the interaction between compressible dynamics, which plays a central role in plasma compression, heating and confinement and incompressible dynamics, which is involved in phenomena like turbulence and self-organization.