Excitation of lower hybrid waves by electron beams in finite geometry plasmas. Part 2. Surface waves

1978 ◽  
Vol 19 (2) ◽  
pp. 295-299
Author(s):  
Réal R. J. Gagné ◽  
Magdi M. Shoucri
Keyword(s):  
Electron Beam ◽  
Surface Waves ◽  
Electron Beams ◽  
Low Frequency ◽  
Finite Geometry ◽  
Dispersion Relations ◽  
Lower Hybrid ◽  
Small Density ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

The dispersion relations for the quasi-static lower hybrid surface waves are derived. Conditions for their existence and their linear excitation by a small density electron beam are discussed. Instabilities appearing in low-frequency surface waves are also discussed.

Excitation of lower hybrid waves by electron beams in finite geometry plasmas. Part 1. Body waves

1978 ◽  
Vol 19 (2) ◽  
pp. 281-294 ◽  
Author(s):  
Magdi M. Shoucri ◽  
Réal R. J. Gagné
Keyword(s):  
Electron Beam ◽  
Electron Beams ◽  
Finite Geometry ◽  
Body Waves ◽  
Lower Hybrid ◽  
Hot Electron ◽  
Cold Electron ◽  
Small Density ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

The quasi-static lower hybrid eigenmodes of a plasma column in a cylindrical waveguide are determined, and their linear excitation by a small density electron beam is discussed for the cases of a hot electron beam as well as for a cold electron beam. It is shown that under certain conditions, finite geometry effects introduce important quantitative and qualitative differences with respect to the results obtained in an infinite geometry.

Lower-hybrid wave generation in an electron beam of finite transverse dimension

1989 ◽  
Vol 41 (1) ◽  
pp. 119-137 ◽  
Author(s):  
G. B. Crew
Keyword(s):  
Electron Beam ◽  
Transverse Dimension ◽  
Beam Current ◽  
Lower Hybrid ◽  
Lower Hybrid Wave ◽  
Field Geometry ◽  
Hybrid Waves ◽  
Limiting Case ◽  
Lower Hybrid Waves

The generation of lower-hybrid waves in an inhomogeneous electron beam is examined. Wave amplitudes are invariably limited by the convective nature of the instability. The self-consistent shear of the magnetic-field geometry due to the beam current is limited to the role of dividing the general problem into separate cases according to the relative orientation of the wave vector and direction of inhomogeneity. Moreover, the limiting case of small shear is smoothly connected to the case where shear is altogether negligible. Estimates of the amplification of lower-hybrid waves propagating across the electron beam are made for the various cases.

On the filamentation of large amplitude lower-hybrid waves

1977 ◽  
Vol 18 (1) ◽  
pp. 165-172 ◽  
Author(s):  
K. H. Spatschek ◽  
P. K. Shukla ◽  
M. Y. Yu
Keyword(s):  
Large Amplitude ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Convective Instabilities ◽  
Modulational Instabilities ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

We consider the propagation of a large-amplitude lower-hybrid wave. Modulational instabilities arising from its interaction with low-frequency electrostatic perturbations are investigated. The growth lengths of the convective instabilities are obtained and compared with previous results for adiabatic perturbations.

Nonlinear propagation of lower-hybrid waves in an inhomogeneous plasma

1978 ◽  
Vol 20 (2) ◽  
pp. 189-203 ◽  
Author(s):  
M. Y. Yu ◽  
P. K. Shukla ◽  
K. H. Spatschek
Keyword(s):  
Nonlinear Evolution ◽  
Inhomogeneous Plasma ◽  
Three Dimensional ◽  
Low Frequency ◽  
Nonlinear Propagation ◽  
Lower Hybrid ◽  
Density Perturbations ◽  
Hybrid Waves ◽  
Lower Hybrid Waves ◽  
Pump Depletion

We investigate the problem of spatial depletion of propagating lower-hybrid waves in an inhomogeneous plasma. In particular, we consider the nonlinear evolution of a lower-hybrid pump which is coupled to a daughter lower-hybrid decay wave excited by low-frequency density perturbations. Our results show that pump depletion occurs when three-dimensional effects are included. This phenomenon competes with the filamentation of the pump caused by self- interaction. Implications to lower-hybrid heating experiments are discussed.

Excitation of lower hybrid waves in a plasma by electron beams

1976 ◽  
Vol 19 (4) ◽  
pp. 605 ◽  
Author(s):  
K. Papadopoulos ◽  
P. Palmadesso
Keyword(s):  
Electron Beams ◽  
Lower Hybrid ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

Spectroscopic investigation of plasma turbulence

1979 ◽  
Vol 57 (6) ◽  
pp. 845-850 ◽  
Author(s):  
Y. S. Al-Shiraida ◽  
A. Hirose ◽  
H. M. Skarsgard
Keyword(s):  
Acoustic Waves ◽  
Energy Transport ◽  
Low Frequency ◽  
Skin Layer ◽  
Lower Hybrid ◽  
Direct Energy ◽  
Main Discharge ◽  
Hybrid Waves ◽  
The University ◽  
Lower Hybrid Waves

Optical studies of plasma fluctuations have been carried out in a toroidal, high-voltage discharge—the Plasma Betatron experiment at the University of Saskatchewan. Following the formation of the helium plasma, of density 1019–1020 m−3, by rf preionization and a preheating field, the electric field (≤ 8 kV/m) of the main discharge is applied parallel to the steady toroidal magnetic field of 0.3 T. Forbidden lines and satellites observed near the He I 21P–41D (4922 Å) and 23P–43D (4471 Å) lines show that low [Formula: see text] and high (ω ~ ωpe) frequency fluctuations are present at early times (t < 2 μs). The rms field strengths are comparable, at [Formula: see text]. An analysis is given of the possible role of these fluctuations in the rapid thermal transport previously observed from the current skin layer to the interior of the plasma. Direct energy transport by propagating electron plasma or ion acoustic waves is shown to be insignificant. However, the low frequency field strength is sufficient to allow for an explanation in terms of enhanced thermal diffusion due to lower hybrid waves.

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