On the nature of large auroral zone electric fields at 1‐R_E altitude

Abstract

Mechanisms that may support magnetic‐field‐aligned electric fields in collisionless plasma are discussed in the light of recent magnetospheric observations, which for the first time allow a quantitative test of the theoretical models. Data from barium ion releases which indicate large field‐aligned potential drops and direct electric field probe measurements at high altitude which reveal electric fields of several hundred millivolts per meter are discussed. It is concluded that the large field strengths observed (1) cannot be explained by anomalous resistivity or thermoelectric effects based on wave‐particle interaction, (2) are much larger than required merely to balance the local mirror forces, and (3) are compatible with electric double layers of the same nature as those observed in the laboratory.

On the estimation of the inductive electric field in the magnetosphere.

“…However, such an assumption need not be valid in the region of intense field aligned currents as shown by the detection of field aligned electric fields of the order of 0.1-1V/ meter along the auroral field lines (MOZER et al, 1977). These electric field have been found to occur within field aligned sheet of approximately 1 km thickness and have been attributed to double layers (SHAWHAN et al, 1978). Apart from this it is possible that anomalous resistivity on the auroral field lines can generate a several KV potential drop along the field line resulting from a parallel electric field of the order of 1mV/meter extending to a length of thousands of kilometers (HUDSON et al, 1978).…”

Double layers and plasma-wave resistivity in extragalactic jets: cavity formation and radio-wave emission

“…The double layers envisioned here have many features in common with auroral zone double layers (Shawhan, 1978;Borovsky, 1984). Auroral double layers accelerate electrons to energies of 1-10 keV, the electrons following the terrestrial magnetic field lines to the upper atmosphere where they produce visible auroral arcs.…”

Recent advances in the study of electric and magnetic fields in the ionosphere and magnetosphere.

“…and CARLQVIST (1978) have both written major reviews of double layer focussing on both the observational and theoretical aspects of the topic. Both the studies of SHAWHAN et al (1978) and HUDSON and MOZER (1978) focus on the nature of the observations of MOZER et al (1977) and how they fit the expectations of any of the proposed auroral acceleration mechanisms. Shawhan et al find that only the double layer is capable of producing the parallel electric fields detected by MOZER et al (1977) (see Table 1).…”

“…The double layer continues to be the subject of active study by the plasma physics group at the Royal Institute of Technology in Stockholm, Sweden. They continue their laboratory studies of double layers (TORVEN, 1978;TORVEN and ANDERSSON, 1979) as well as the investigation of the applicability of this phenomenon to auroral particle acceleration (SHAWHAN et al, 1978). and CARLQVIST (1978) have both written major reviews of double layer focussing on both the observational and theoretical aspects of the topic.…”