Electrostatic Double Layers
Location
Yosemite National Park
Start Date
2-8-1974 8:45 AM
End Date
2-8-1974 9:15 AM
Description
An efficient mechanism for acceleration of auroral particles may be through electrostatic double layers. Birkeland-currents can create favorable conditions for double layers by reduction of the electron density at high altitudes. When double layers appear, a reduction of the current density will occur due to broadening of the current-carrying region in response to the increased resistivity associated with the double layers. However, the double layers will persist, and a balance can be established between the current-broadening and concentrating effects operative in the low ionosphere. Methods to observe double layers with rockets and satellites include measurements of pitch-angle distributions with high resolution, three-axis electric double probes, and topside sounders. Due to the small field-aligned extent (10-100 Debye-lengths) of double layers, they will only show up as spikes of short duration in the output signal of a double probe. Such signals should therefore not be discarded as spurious, but analyzed carefully. Simultaneous measurements of Birkeland-currents, electron density, ion composition, and fluxes and energies of precipitating and upgoing particles are also very desirable, but they cannot alone discriminate between double layers and other anomalous resistivity effects.
Electrostatic Double Layers
Yosemite National Park
An efficient mechanism for acceleration of auroral particles may be through electrostatic double layers. Birkeland-currents can create favorable conditions for double layers by reduction of the electron density at high altitudes. When double layers appear, a reduction of the current density will occur due to broadening of the current-carrying region in response to the increased resistivity associated with the double layers. However, the double layers will persist, and a balance can be established between the current-broadening and concentrating effects operative in the low ionosphere. Methods to observe double layers with rockets and satellites include measurements of pitch-angle distributions with high resolution, three-axis electric double probes, and topside sounders. Due to the small field-aligned extent (10-100 Debye-lengths) of double layers, they will only show up as spikes of short duration in the output signal of a double probe. Such signals should therefore not be discarded as spurious, but analyzed carefully. Simultaneous measurements of Birkeland-currents, electron density, ion composition, and fluxes and energies of precipitating and upgoing particles are also very desirable, but they cannot alone discriminate between double layers and other anomalous resistivity effects.