Showing papers by "Mary K. Hudson published in 1986"
TL;DR: In this article, the main modes excited include the upper hybrid oscillation for nearly perpendicular propagation, the whistler mode at oblique angles, which becomes the plasma two-stream oscillations for parallel propagation, and the electron acoustic mode for nearly parallel propagation.
Abstract: Excitation of waves by electron distributions consisting of hot, beam, and cold populations is investigated theoretically and with the help of particle simulations. The main modes excited include the upper hybrid oscillation for nearly perpendicular propagation; the whistler mode at oblique angles, which becomes the plasma two-stream oscillation for parallel propagation; and the electron acoustic mode for nearly parallel propagation. The whistler mode, excited by thermal fluctuation enhancement, has a broad range of wave numbers and quasi-linearly decreases the beam slope, while the electron acoustic mode, which is linearly unstable, has a narrow spread in phase velocities and traps the beam and the warm electrons forming a double humped distribution. Both modes contribute to forming a tail in the cold electron distribution. The resulting wave spectrum is discussed in the context of DE 1 observations.
31 citations
TL;DR: In this paper, a cold fluid approach is presented which yields exact double-layer solutions that can be used to model electrostatic S-type shocks, and the dependence of various double layer quantities on plasma composition is then considered for the cold electron beam model.
Abstract: A cold fluid approach is presented which yields exact double-layer solutions that can be used to model electrostatic S-type shocks. Solutions derived from the two-temperature electron model are presented in order to show the range of amplitudes and scale lengths possible for this plasma model and to examine how shock properties depend on orientation of the shock. The dependence of various double-layer quantities on plasma composition is then considered for the cold electron beam model. Double-layer solutions pertinent to describing electrostatic shocks are pointed out.
10 citations
01 Jan 1986
TL;DR: In this paper, it was shown that there is little difference between having a finite temperature in the electron beam and leaving the beam cold, which implies a greater utility for a cold electron beam model and adds weight to the idea that the smaller amplitude electrostatic shocks seen in conjunction with ion beams are nonlinear ion acoustic modes.
Abstract: A plasma model consisting of warm downward streaming electrons, cool Boltzmann electrons, cold upward streaming ions, and hot Boltzmann ions is considered. It is shown that there is little difference between having a finite temperature in the electron beam and leaving the beam cold. This implies a greater utility for a cold electron beam model, and adds weight to the idea that the smaller amplitude electrostatic shocks seen in conjunction with ion beams are nonlinear ion acoustic modes.
1 citations