Ponderomotive manipulation of cold subwavelength plasmas

Abstract

Ponderomotive forces (PFs) induced in cold subwavelength plasmas by an externally applied electromagnetic wave are studied analytically. To this end, the plasma is modeled as a sphere with a radially varying permittivity, and the internal electric fields are calculated by solving the macroscopic Maxwell equations using an expansion in Debye potentials. It is found that the PF is directed opposite to the plasma density gradient, similarly to large-scale plasmas. In the case of a uniform density profile, a residual spherically symmetric compressive PF is found, suggesting possibilities for contactless ponderomotive manipulation of homogeneous subwavelength objects. The presence of a surface PF on discontinuous plasma boundaries is derived. This force is essential for a microscopic description of the radiation-plasma interaction consistent with momentum conservation. It is shown that the PF integrated over the plasma volume is equivalent to the radiation pressure exerted on the plasma by the incident wave. The concept of radiative acceleration of subwavelength plasmas, proposed earlier, is applied to ultracold plasmas. It is estimated that these plasmas may be accelerated to keV ion energies, resulting in a neutralized beam with a brightness comparable to that of current high-performance ion sources.

On the Thrust of a Single Electrode Electrohydrodynamic Thruster

“…where e is particle charge, m particle weight, ω oscillation frequency of the field and E field strength, becomes the dominant mechanism of thrust creation. Ponderomotive force is present in inhomogeneous oscillating fields and acts on both positive and negative charges in the direction opposite to the gradient of the field [6]. If the field gradient around emitter was symmetrical, the ponderomotive force would have the same value in every direction, thus cancelling out and producing no net thrust.…”

Classical formulations of the electromagnetic self-force of extended charged bodies

“…Therefore alternative postulates, such as the Abraham model or other non-rigid models [27], may continue to prove their value. What is more, the current state of technology is starting to enable experimental conditions in which the electromagnetic self-force of macroscopic charged systems, such as high-density electron bunches [55] and ultracold plasma bunches [56], becomes significant. It would be interesting to see to what extent the self-force formulations in this paper can model these evidently non-rigid systems.…”