E.A. Kornilov

Theoretical and experimental investigations of a neutralized ion induction linac for inertial confinement fusion

Abstract Studies of an induction linac for space-charge-neutralized beams, comprising an injector and two induction stages with magnetoinsulating cusps in the a

Stabilization of beam instability by a local instability developing due to a wave-wave interaction

A new mechanism for stabilization and suppression of beam instabilities is proposed. This mechanism, which is based on the stochastic instability of a wave-wave interaction process, plays a particularly important role in plasma systems with a small region of interaction between the beam particles and the excited waves.

Investigation of low-frequency waves in plasma-filled microwave oscillators

The excitation of microwave oscillations by an electron beam in a hybrid plasma waveguide—a slow-wave structure (a sequence of inductively coupled resonators) with a plasma-filled transport channel—is studied both experimentally and theoretically. It is shown that the governing role in the generation of microwaves and their transmission to a feeder line is played by the spatial and temporal plasma-density variations associated with low-frequency ion plasma oscillations. The microwave pressure gives rise to low-frequency plasma oscillations with a rise time shorter than their period. This nonlinear mechanism for the excitation of low-frequency oscillations has a threshold in terms of the microwave power. The unsteady character of the spatial distribution of the plasma density results in intermittent microwave generation and shortens the duration of microwave pulses.

Excitation of broadband oscillations by electron beam in coaxial disk loaded transmission line

The excitation by an electron beam of UHF oscillations in coaxial slowing down transmission line with comb on internal and external cylinders is considered. The analytical and numerical analysis of the received dispersion equation is carried out. The dependence of the gain on energy of an electron beam is investigated. It is shown, that the dependence of the gain on frequency has a maximum nearby Cherenkov resonance of a beam with an eigenwave of structure, outside of a resonance the gain falls down under the linear law at reduction of frequency. The nonlinear theory of the UHF amplifier is constructed on the basis of the chosen slowing down structure. The maximal amplitude of a longitudinal electrical field, efficiency of interaction, optimum length of structure are determined.

Obtainment of electromagnetic radiation at interaction of electron beam with ring plasma waveguide

One of the principle purposes is the research of the most effective method of extraction of energy of the oscillations excited by an electron beam from plasma into the outer space or high frequency (HF) tracks. The most attractive solution of this problem, is presented with hybrid plasma waveguides that combine advantages of the both plasma waveguides and the standard slow wave structures.

Acceleration of high-current ion beams in the induction linac

Abstract It is shown that 3–4 kA ion beams may be effectively postaccelerated by a linear induction accelerator comprising insulating magnetic cusps in its ga

Excitation of RF Oscillations in a Discharge with Negative Differential Conductivity

The excitation of oscillations in a discharge with negative differential conductivity is studied experimentally. The possibility is demonstrated of amplifying oscillations in the cathode dark space at frequencies close to the electron plasma frequency of the positive-column plasma. The phase velocities of waves at these frequencies are determined. When the waves pass from the cathode dark space to the discharge positive column, their phase velocities decrease; the closer the frequency is to the electron plasma frequency, the more pronounced the decrease in the phase velocity. As the intensity of oscillations increases, the discharge becomes non-steady-state. This is confirmed by the time evolution of the current-voltage characteristic. The shape of the current-voltage characteristic, its splitting, and the rate at which it varies depend on the input RF power. The decrease in the cathode dark space indicates that the ionization processes in the discharge are strongly influenced by electron plasma oscillations excited due to the collective interaction of the electron beam formed at the cathode with the discharge plasma. It is these processes that determine the maximum values of both the frequency of the excited oscillations and the power that can be withdrawn from the discharge.

Beam-Plasma Interaction in a Hybrid Plasma Waveguide in the Pulsed Mode of Microwave Generation

Results are presented from experimental studies of the energy spectra of an electron beam in a model beam-plasma oscillator based on a hybrid plasma waveguide in the pulsed mode of microwave generation with a pulse duration of 1 µs or shorter. The beam energy spent on sustaining the beam-plasma discharge in a slow-wave structure is measured. A correlation between the type of excited waves and the generation of a group of accelerated beam electrons with energies exceeding the injection energy is revealed. It is shown that the pulsed mode of microwave generation is related to the time variations in the plasma density profile in the waveguide and the trapping of beam electrons by the excited microwave field.

Effect of plasma nonlinearity on the beam-plasma interaction in a hybrid plasma waveguide

A study is made of the characteristic features of the effect of plasma nonlinearity in a slow-wave structure on microwave generation by an electron beam and on electron beam energy losses. Theoretical results on the plasma density variation, the amplitude of the excited microwaves, and the velocity distribution function of the beam electrons are compared with the experimental data. It is shown that the self-consistency between the decreasing plasma density gradient and the spatial variation of the amplitude of an amplified wave in a slowwave structure leads to a significant (severalfold) increase in the efficiency with which the electron beam energy is converted into microwave energy in short pulses. The predictions of the theoretical model developed to describe the non-steady-state beam-plasma interaction agree well with the experimental data.

Parametric excitation of electromagnetic radiation by electron beam in layer plasma waveguide

In this work, the process of electromagnetic radiation (EMR) excitation by an electron beam is also investigated in the case of plasma waveguides where the plasma density varies along the system according to the periodic (harmonic) law. In the examined system, the plasma wave is synchronous with the beam. The plasma wave is parametrically coupled with the fast electromagnetic wave (EMW) propagating in the vacuum gap between the plasma boundary and the conductive jacket. The coupling is stimulated by the plasma density periodic inhomogeneity. It is demonstrated that in this system the process of the plasma wave parametric transformation into EMR stimulates increase of efficiency of the power pumpover from the electron beam.