Artificial Aurora Experiments and Application to Natural Aurora

Abstract

A review is given of the effects observed during injections of powerful electron beams from sounding rockets into the upper atmosphere. Data come from in situ particle and wave measurements near a beam-emitting rocket and ground-based optical, wideband radiowave, and radar observations. The overall data cannot be explained solely by collisional degradation of energetic electrons but require collisionless beam-plasma interactions (BPI) be taken into account. The beam-plasma discharge theory describes the features of the region near a beam-emitting rocket, where the beam-excited plasma waves energize plasma electrons, which then ignite the discharge. The observations far beneath the rocket reveal a double-peak structure of artificial auroral rays, which can be understood in terms of the beam-excited strong Langmuir turbulence being affected by collisions of ionospheric electrons. This leads to the enhanced energization of ionospheric electrons in a narrow layer termed the plasma turbulence layer (PTL), which explains the upper peak. Similar double-peak structures or a sharp upper boundary in rayed auroral arcs have been observed in the auroral ionosphere by optical, radar, and rocket observations, and called Enhanced Aurora. A striking resemblance between Enhanced and Artificial Aurora altitude profiles indicates that they are created by the above BPI process which results in the PTL.

Dayside Low Energy Electron Precipitation Driven by Hiss Waves in the Presence of Ionospheric Photoelectrons

“…The same flux ratio configuration between the upward and downward fluxes, like it is displayed in Figure 6c, forms in the Southern Hemisphere (not shown here) and creates an additional electron instability situation of two electron beams moving toward each other. All these processes, however, are out of the scope of this manuscript and require additional analysis (Mishin, 2019).…”

Beam–Plasma Discharge in Space and in a Lab

“…A detailed review of research concerning BPD in application to natural and artificial auroras can be found in [53]; therefore, we do not continue this topic here.…”

“…An example of near-missile glow and artificial radiance rays in "Zarnitsa 2." On the right is the vertical profile of the left: ray of AA with the superimposed Monte Carlo profile (from[53]).…”

Langmuir Turbulence in the Auroral Ionosphere: Origins and Effects

“…Many details and discussions from the literature are not repeated here-for which, readers are routinely guided to the referenced original papers. Furthermore, this review only includes studies related to Langmuir waves produced naturally by electron beams in space plasmas and does not cover laboratory studies, results observed during injection of artificial electron beams in the ionosphere (a review provided by Mishin (2019)), or Langmuir turbulence induced in ionospheric modification experiments.…”