Auroral particle acceleration by strong double layers: The upward current region

Particle Acceleration and Wave Phenomena in the Auroral Region

1 I n t r o d u c t i o n The auroral region of the terrestrial magnetosphere is a fascinating part of space, and also a part that can be investigated in some detail with satellites, sounding rockets and groundbased instruments. The second EGS Alfv~n conference held in Stockholm May 3-7 1999 was devoted to auroral particle acceleration and related topics. This meeting produced a variety of inte...

Particle Acceleration by Alfvén Waves in the Auroral Zone

Double layers in the downward current region of the aurora

Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields orga...

Ponderomotive Acceleration in the Auroral Region A Kinetic Simulation

Alfvtn waves with frequencies of the order of several Hertz have been observed in the auroral region. These waves are thought to be responsible for the acceleration f !0nosphen'c particles out of the ionosphere and into the magnetosphere. As an Alfvtn wave propagates into an inhomogeneous ionosphere, the amplitude of the wave decreases resulting in a gradient in the electric field and a pondero...

AKR breakup and auroral particle acceleration at substorm onset

[1] The dynamical behavior of auroral kilometric radiation (AKR) is investigated in connection with auroral particle acceleration at substorm onsets using high-time-resolution wave spectrograms provided by Polar/PWI electric field observations. AKR develops explosively at altitudes above a preexisting low-altitude AKR source at substorm onsets. This ‘‘AKR breakup’’ suggests an abrupt formation ...