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Detection of bump‐on‐tail reduced electron velocity distributions at the electron foreshock boundary
Journal article   Peer reviewed

Detection of bump‐on‐tail reduced electron velocity distributions at the electron foreshock boundary

Richard J Fitzenreiter, Alexander J Klimas and Jack D Scudder
Geophysical research letters, Vol.11(5), pp.496-499
05/1984
DOI: 10.1029/GL011i005p00496

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Abstract

Reduced velocity distributions are derived from three‐dimensional measurements of the velocity distribution of electrons in the 7‐500 eV range in the electron foreshock. Bump‐on‐tail reduced distributions are presented for the first time at the foreshock boundary consistent with Filbert and Kellogg's proposed time‐of‐flight mechanism for generating the electron beams. In a significant number of boundary crossings, bump‐on‐tail reduced distributions were found in consecutive 3 sec measurements made 9 sec apart. We conclude that, although the beams are linearly unstable to plasma waves according to the Penrose criterion, they persist on a time scale of 3‐15 sec.

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