Two-stream instability

Abstract: ELECTRONS in a plasma undergo collective wave-like oscillations near the plasma frequency. These plasma waves can have a range of wavelengths and hence a range of phase velocities1. Of particular note are relativistic plasma waves2,3, for which the phase velocity approaches the speed of light; the longitudinal electric field associated with such waves can be extremely large, and can be used to accelerate electrons (either injected externally or supplied by the plasma) to high energies over very short distances2a¤-4. The maximum electric field, and hence maximum acceleration rate, that can be obtained in this way is determined by the maximum amplitude of oscillation that can be supported by the plasma5a¤-8. When this limit is reached, the plasma wave is said to a¤˜breaka¤™. Here we report observations of relativistic plasma waves driven to breaking point by the Raman forward-scattering instability9,10 induced by short, high-intensity laser pulses. The onset of wave-breaking is indicated by a sudden increase in both the number and maximum energy (up to 44 MeV) of accelerated plasma electrons, as well as by the loss of coherence of laser light scattered from the plasma wave.

Abstract: A new theory of the mirror instability is developed which includes the effects of ∇B and ∇n, finite Larmor radius, and a coexisting cold plasma It is shown that the instability becomes overstable with a frequency equal to the drift wave frequency, which may be determined by the wave‐number that gives the maximum growth rate The theory is applied to explain the sudden kink in the increase (decrease) of proton flux (magnetic field) and the subsequent oscillations observed during a storm time on 18 April 1965 by detectors on the Explorer 26 satellite

Abstract: It is shown that, for a large class of statistical mixtures, the Wigner-Poisson (or Hartree) system can be reduced to an effective Schroedinger-Poisson system, in which the Schroedinger equation contains a new nonlinearity. For the case of a zero-temperature one-dimensional electron gas, this additional nonlinearity is of the form vertical bar {Psi} vertical bar{sup 4}. In the long-wavelength limit, the results obtained from the effective Schroedinger-Poisson system are in agreement with those of the Wigner-Poisson system. The reduced model is further used to describe the stationary states of a quantum electron gas and the two-stream instability.