The authors investigate Cerenkov heating in a radially non-uniform plasma cylinder, taking into account the effect of oscillations on the ‘background’ charged particle distribution function. They derive equations for particle diffusion in velocity space which are valid for both ‘narrow’ and ‘broad’ wave packets, and also expressions for the energy absorbed by the plasma. The effect of collisions is taken into account. The energy gained per unit time by an ion is estimated for the case of ‘broad’ wave packets, when the ‘background’ distribution function is non-Maxwellian to an insignificant extent. It is shown that in the case of ‘narrow’ wave packets, when the coefficient of diffusion in velocity space (characterizing the effect of oscillations on the ‘background’ distribution function) exceeds the coefficient of diffusion due to collisions, ‘absorption saturation’ ensues and an increase in the amplitude of the electromagnetic field does not lead to an increase in absorbed energy. It is also shown that heating with ‘narrow’ wave packets is no less effective than heating with ‘broad’ wave packets, provided that the ‘background’ distribution function in the latter case is not significantly non-Maxwellian.

On the basis of the theory of weak turbulence it is shown that the principal mechanism limiting the development of ion-acoustic instability in a current-carrying plasma in an electric field can be the non-linear scattering of oscillations by electrons. The energy density of turbulent ion-acoustic pulsations is of the order W∼(2me/mi)n0 Te, where n0 is the plasma density, Te the electron temperature and m6ij the electron and ion mass.Electron scattering by turbulent pulsations occurs with an effective frequency νs ∼ (2me/mi) ωpe and leads to an anomalous effective plasma conductivity , where ωpe is the electron Langmuir frequency.Ion-acoustic instability develops in a plasma in weak electric fields (E

The authors investigate the stability of a collisionless plasma in which the ions are moving relative to the electrons at right angles to the applied magnetic field, under the influence of the electric field of an ion-cyclotron wave, with a velocity u⃗⊥ that is less than or commensurate with the thermal velocity of the ions vi. They study the excitation of longitudinal electrostatic oscillations with frequency and growth rate significantly greater than the gyrofrequency of the ions, but significantly less than that of the electrons, and with a wavelength significantly less than that of the ion-cyclotron wave. It is shown that, when the ion temperature Ti is significantly higher than the electron temperature Te. electron-acousticoscillations are excited in the plasma. The excitation of these oscillations by resonance ions is possible even when u⊥ ≪ vi. When Te ≫ Ti ion-acoustic oscillations are excited in the plasma, the build-up of these oscillations by the ions being the result of absorption by resonance electrons. When Te ⪆ Ti oscillations are excited if the velocity of the ion beam u⊥ is somewhat greater than the thermal velocity of the ions. When Ti ≫ Te. the reactive effect of the oscillations causes the function representing resonance ion distribution in the beam direction to level off and form a plateau. When Te ≫ Ti the unstable ion-acoustic oscillations spread the resonance electron distribution function, which is equivalent to electron heating, and slow down the ion beam.

The authors consider a number of methods of determining the density and temperature distributions along the radius of a plasma cylinder. Determination of the electron density and temperature distributions by measuring the electron cyclotron damping or the phase of an electromagnetic wave passing in a straight line through a plasma cylinder as a function of the “sighting” distance. If the electron velocity distribution is not Maxwellian, additional measurements of the absorption or the phase as a function of the magnetic field or of the angle between the direction of the ray and the magnetic field enable one to find the electron velocity distribution function along the magnetic field at each point in the plasma cylinder. Determination of the plasma density distribution from the fraction of a microwave ray passing through a plasma in a direction perpendicular to the magnetic field, and determination of the effective collision frequency distribution from damping of the intensity of the refracted ray. Determination of the temperature of a plasma in a strong magnetic field from the measured frequency-dependence of the absorption of low-frequency electromagnetic waves under conditions of acoustic resonance.

The development of Buneman's kinetic-type instability in plasma with hot ions and cold electrons is investigated. Expressions for the frequencies and growth rates of oscillations when the current velocity slightly exceeds the instability threshold velocity have been derived in the linear approximation. The quasilinear theory of instabilities has been developed, and it has been shown that the quasi-linear effects lead to the amplification of the instability.