Ponderomotive potential in a complex plasma

A ponderomotive potential is studied theoretically for a complex plasma. Relativistic dust particles placed in an oscillating electromagnetic field in a plasma are subject to the relativistic equation of motion. Classical dynamics reveals that the ponderomotive potential for dust particles is a nonlinear potential, and the potential is found to become much stronger in the presence of a magnetic field than that in the absence of the magnetic field. Dynamics of spinning dust particles characterized by a spin parameter s (moment of inertia multiplied by the rotating frequency) is formulated by the language of quantum mechanics, where s is replaced by a spin operator. Although quantum mechanics is not required for massive dust particles and is chosen merely for methodological reasons, the formulation reveals the presence of polarization as well as the presence of magnetization in a complex plasma. Semiclassical analysis shows that polarization produces the Kelvin polarization force in a nonuniform electric field, while magnetization produces the Kelvin magnetization force in a nonuniform magnetic field in a complex plasma. Dust particles, characterized by heavy mass and various charges, could be accelerated effectively if the frequency of the applied electromagnetic fields matches with the relativistic dust plasma frequency and resonates with the relativistic dust cyclotron frequency.