Measurements with the SPE‐1 instrumentation on board the low‐altitude satellite, Active, provide energy spectra of electrons in three directions and in 7, 15, or 31 energy channels quasi‐logarithmically distributed approximately within the interval from 20 to 400 keV. The orbit allowed measurement of electrons in the altitude range from 500 to 2500 km and in all local time sectors within any 3‐month interval. In the inner zone, multiple peaks, with the lowest one at 30 keV, are found in the trapped population at L<1.30 and at altitudes above 800 km. The long drift period of such electrons indicates that the drift acceleration resonance model proposed to explain peaks at higher energies is inappropriate here.

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Abstract. A new phenomenon was found at the polar edge of the auroral oval in the postmidnight±morning sectors: ®eld-aligned (FA) high-energy upward electron beams in the energy range 20±40 keV at altitudes about 3 R E , accompanied by bidirectional electron FA beams of keV energy. The beam intensity often reaches more than 0X5 Á 10 3 electronsas Á sr Á keV Á cm 2 , and the beams are observed for a relatively long time $3 Á 10 2 ±10 3 s, when the satellite at the apogee moves slowly in the ILAT-MLT frame. A qualitative scenario of the acceleration mechanism is proposed, according to which the satellite is within a region of bidirectional acceleration where a stochastic FA acceleration is accomplished by waves with¯uctuating FA electric ®eld components in both directions.

No abstract

A new phenomenon was found at the polar edge of the auroral oval in the postmidnight±morning sectors: ®eld-aligned (FA) high-energy upward electron beams in the energy range 20±40 keV at altitudes about 3 R E , accompanied by bidirectional electron FA beams of keV energy. The beam intensity often reaches more than 0X5 Á 10 3 electronsas Á sr Á keV Á cm 2 , and the beams are observed for a relatively long time $3 Á 10 2 ±10 3 s, when the satellite at the apogee moves slowly in the ILAT-MLT frame. A qualitative scenario of the acceleration mechanism is proposed, according to which the satellite is within a region of bidirectional acceleration where a stochastic FA acceleration is accomplished by waves with¯uctuating FA electric ®eld components in both directions.