EFFICIENCY OF THE EMISSION OF ELECTROMAGNETIC-WAVES EXCITED IN THE INTERACTION OF AN ELECTRON-BEAM WITH A RADIALLY BOUNDED PLASMA IN A NONUNIFORM AXIAL MAGNETIC-FIELD
Ea. Kornilov et al., EFFICIENCY OF THE EMISSION OF ELECTROMAGNETIC-WAVES EXCITED IN THE INTERACTION OF AN ELECTRON-BEAM WITH A RADIALLY BOUNDED PLASMA IN A NONUNIFORM AXIAL MAGNETIC-FIELD, Plasma physics reports, 24(11), 1998, pp. 971-979
Results of experimental studies of the interaction of an electron beam
with a radially bounded plasma are presented. It is shown that, for t
he given beam parameters, the efficiency of the excitation of plasma o
scillations can be substantially increased through an appropriate choi
ce of the plasma radius. By adjusting the radial plasma density gradie
nt, it is possible to achieve a high efficiency of the conversion of b
eam-excited oscillations into electromagnetic waves. It is demonstrate
d that the directional diagram of the electromagnetic radiation emitte
d from the beam-plasma system can be controlled by varying the longitu
dinal plasma inhomogeneity, i.e., by varying the longitudinal profile
of the axial magnetic field. It is shown that the radial inhomogeneity
of the plasma density can suppress ion-acoustic and drift instabiliti
es. Electromagnetic radiation is observed against the background of th
e excitation of lower hybrid oscillations and acceleration of plasma i
ons in the fields of these oscillations in the direction of beam propa
gation. The level of low-frequency ion-acoustic, drift, and lower hybr
id oscillations determines the maximum power of high-frequency oscilla
tions excited in a beam-plasma system.