Quenching of plasma oscillation by a low-frequency externally applied wave

It is shown that the electron plasma oscillation is also quenched by a low-frequency externally applied wave, with generation of plural side bands. The phenomenon is described by a coupled Van der Pol-Mathieu equation.     

Interaction of electromagnetic waves with a magnetized nonuniform plasma slab

The absorption, reflection, and transmission of electromagnetic waves by a nonuniform plasma slab immersed in an ambient uniform magnetic field of various strengths are studied in this paper. The effects of the plasma parameters and magnetic field strength on the absorbed, reflected, and transmitted power are discussed. The magnetized nonuniform plasma slab is modeled by a series of magnetized uniform plasma subslabs. The calculation results show that the effects of the magnetic field strength and density gradient on the absorbed power, as well as the frequency band of resonant absorption, are significant. A complete analysis utilizing the scattering matrix method is also used to compare the above calculation results which neglect multiple reflections between subslab interfaces. Broadband absorption of electromagnetic waves can be achieved by changing the magnetic field strength and plasma density. More than 90% of the electromagnetic wave power can be absorbed in a magnetized nonuniform plasma slab with width of 12 cm and the absorption bandwidth can range from 1 to 20 GHz with different plasma parameters and external magnetic field strengths.     

Total absorption of an electromagnetic wave by an overdense plasma

We show both theoretically and experimentally that an electromagnetic wave can be totally absorbed by an overdense plasma when a subwavelength diffraction grating is placed in front of the plasma surface. The absorption is due to dissipation of surface plasma waves (plasmons polaritons) that have been resonantly excited by the evanescent component of the diffracted electromagnetic wave. The developed theoretical model allows one to determine the conditions for the total absorption.     

Generation of electromagnetic waves by a rotating plasma

Generation of electromagnetic waves by an annular shell of plasma rotating in crossed radial electrostatic and axial magnetic fields in a cylindrical resonator is investigated theoretically. Dispersion relations are obtained describing the interaction of the waves with the plasma. It is shown that generation of waves by a narrow plasma shell is possible due to a cyclotron resonance, Čerenkov resonance, or plasma resonance. Here we consider a Čerenkov resonance, where the velocities of the plasma components and the phase velocities of the waves are perpendicular to the constant magnetic field. The frequencies and growth rates of the waves are found under conditions of the above-mentioned resonances in a uniform and in a nonuniform plasma shell. Advantages and disadvantages of wave generation under various conditions are noted. Zh. Tekh. Fiz. 69, 16–21 (February 1999)     

Current drive by an HF electromagnetic wave in a magnetized plasma

The problem of current drive by an HF wave is analyzed in a one-particle model of a magnetized plasma. A general expression for the current drive is derived by an averaging method in the nonrelativistic case, in second order in the expansion parameter. The presence of a constant and strong magnetic field, the presence of a constant electric field, and the dynamic friction effect are all taken into account. For a monochromatic wave with an amplitude which varies slowly in time and space, expressions for the current drive are derived in closed form. The mechanism for the current drive is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 87–91, March, 1989.     

Vacuum pair-production in a classical electric field and an electromagnetic wave

Using semiclassical WKB-methods, we calculate the rate of electron–positron pair-production from the vacuum in the presence of two external fields, a strong (space- or time-dependent) classical field and a monochromatic electromagnetic wave. We discuss the possible medium effects on the rate in the presence of thermal electrons, bosons, and neutral plasma of electrons and protons at a given temperature and chemical potential. Using our rate formula, we calculate the rate enhancement due to a laser beam, and discuss the possibility that a significant enhancement may appear in a plasma of electrons and protons with self-focusing properties.     

Excitation of an ionospheric Alfvén resonator by a plasma wave discharge

We present a theoretical interpretation of the excitation of an ionospheric Alfvén resonator (IAR) by an electron beam propagated along the external magnetic field. The growth rate of generated Alfvén waves is found and the IAR excitation efficiency is estimated. The theoretical results are in qualitative agreement with the experimental data.Lobachevsky State University, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 3-4, pp. 312–317, March–April, 1995.     

Excitation of wake-field waves in plasma by a microtron beam

The experimental study of excitation of wake-field waves in plasma by a sequence of electron bunches of a microtron beam has been carried out. Results of measurement of the spectrum of electrons after their passage through plasma confirm the effect of adding of waves from a sequence of about 100 bunches which leads to the increase in the amplitude from 1 V/cm up to 100 V/cm.