The electrohydrodynamic phenomena associated with the high-velocity motion of a charged body in a plasma are investigated with a view to applications to satellite motion in the ionosphere. It is shown that the effect of the electric field due to the charge on the body in inducing collective motion leads to similar results both for high- and low-density gases. By using a linearized theory, formulas are obtained for the electrohydrodynamic drag and for the increased ionization in the Mach cone behind the body.
In this communication we have considered propagation in a weakly anisotropic dielectric waveguide. It is shown that for a positive anisotropy the fractional power carried by the guide core increases over the isotropic case and that the anisotropy has an increasing effect as cutoff is approached. For negative anisotropy the effect is reversed. The increase in the fractional power varies linearly with the value of anisotropy with slope increasing as cutoff is approached. The degeneracy between the HE(n+1,m) and EH(n+1,m) modes present in the isotropic weakly guiding approximation is broken, and it is physically significant to distinguish between EH and HE modes. The anisotropy in retinal receptors (considered as dielectric waveguides) increases the stability of modal power with variation of the wavelength, although the effect is too small to explain the observation.
The diffusion of electromagnetic energy into a cylindrical plasma column due to the discharge of the energy stored in a capacitor is formulated taking into account the effects of the capacitance and inductance of the discharge circuit. The discharge circuit reflects the linear pinch geometry in that the energy source is a charged condenser and the return lead is a perfectly conducting cylindrical shell concentric with and surrounding the plasma column. The plasma properties enter the formulation through an extended Ohm's law which includes the time rate of change of current density. Under the assumption that changes in the ionization density and collision frequency may be neglected, Maxwell's equations lead to a third-order linear partial differential equation for the diffusion current. An exact solution is obtained by Laplace transform techniques using appropriate initial and boundary conditions which take into account the finite external circuitry. The spatial and temporal behavior of the current density distribution as functions of the parameters which characterize both the circuit and the plasma are discussed and compared with that of an ordinary conductor obeying the simple Ohm's law.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.