Observation of an ionospheric acceleration mechanism producing energetic (keV) ions primarily normal to the geomagnetic field direction

Sharp, R. D.; Johnson, R. G.; Shelley, E. G.

doi:10.1029/ja082i022p03324

Cited by 356 publications

(150 citation statements)

References 3 publications

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“…Acceleration from magnetic field-aligned potential drops is known to occur at several 1000 km altitudes above auroral arcs (e.g., Mozer et al 1977;Sharp, Johnson, & Shelley 1977;Gorney et al 1981). It is thus the closest realization of a powerful cosmic acceleration process, easy to probe, and, indeed, documented by a wealth of data (a good collection of papers with data from the Swedish Viking satellite can be found in the May issue [no.…”

Section: Introductionmentioning

confidence: 99%

Acceleration from Field-Aligned Potential Drops

Haerendel

1994

International Astronomical Union Colloquium

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Unstable field-aligned currents are seen as the origin of field-aligned potential drops. They convert energy stored in magnetic shear stresses into kinetic energy. A good fraction of this energy is carried by runaway electrons and ions out of the acceleration region. The paper emphasizes the analogy with mechanical fractures. Simple expressions for the energy conversion rate and the parallel potential drop are derived, the two being linked by the critical current density needed for instability. The origin of the currents (generator) lies mostly in a region remote from that of energy conversion (fracture zone). The transmission of shear stresses and energy from the generator plasma, where the primary forces are applied to the fracture zone is also considered. A closed set of relations allows quantitative evaluation of the energetic particle production efficiency. The decoupling of the plasma on either side of the fracture zone which allows fast stress relief is described in detail, as well as a stationary model for the Alfven wave interaction between fracture zone and generator plasma. A simple concept of the nature of the anomalous resistivity generated by the unstable current leads to an expression for the magnetic diffusivity inside the fracture zone and an estimate of the latter's extent parallel to the magnetic field, whereas its width and length transverse to B follow from the macroscopic relations. Finally and as an example, the theory is applied to the problem of fast electron (and ion) acceleration well above 1 MeV seen to occur in many solar flares. It is obvious that this process belongs to the most powerful production processes of high-energy particles in stellar magnetic fields.

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Section: Introductionmentioning

confidence: 99%

Acceleration from Field-Aligned Potential Drops

Haerendel

1994

International Astronomical Union Colloquium

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“…Experimental evidence for perpendicular ion acceleration (ion conics) has been accumulated from at least four magnetospheric satellites and two sounding rockets (Shelley et al, 1976;Sharp et al, 1977;Klumpar, 1979;Horwitz, 1980;Whalen et al, 1978, Yau et al, 1982. In contrast there exists scant evidence for the mechanism that produces perpendicular ion acceleration.…”

Section: Introductionmentioning

confidence: 99%

A search for the plasma processes associated with perpendicular ion heating

Kintner¹,

Gorney²

1984

J. Geophys. Res.

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“…It has also been suggested that electrostatic ion-cyclotron waves may be responsible for the production of ion conics [Sharp, 1977], energetic (keV) HI and 0* ions having pitch-angle distributions peaked at an angle to the magnetic field. Ions may be heated in the direction perpendicular to the magnetic field (transverse acceleration) [Ungstrup et al, 19791 in the presence of ion-cyclotron waves, and subsequently flow upward under the magnetic mirror force producing ion beams or conics.…”

Section: [-mentioning

confidence: 99%

Laboratory observations of ion cyclotron waves associated with a double layer in an inhomogeneous magnetic field

Alport¹,

Cartier²,

Merlino³

1986

J. Geophys. Res.

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Observations of coherent electrostatic ion cyclotron (EIC) waves associated with a strong, magnetized double layer are presented. The double layers are produced in a weakly ionized argon plasma by applying a positive potential to an electrode plate located in the diverging magnetic field region of a cylindrical plasma column. Ionization within the electrode sheath is essential to the formation of these double layers. The resulting V‐shaped potential structures have extended parallel, oblique and perpendicular (to B) electric field components. The frequency of the ion cyclotron instability is dependent upon the magnetic field strength at the position of the parallel potential structure. The properties of EIC waves in the presence of the double layer are discussed in relation to the possible excitation mechanisms (field‐aligned currents, ion and electron beams, and perpendicular E fields).

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Observation of an ionospheric acceleration mechanism producing energetic (keV) ions primarily normal to the geomagnetic field direction

Cited by 356 publications

References 3 publications

Acceleration from Field-Aligned Potential Drops

Acceleration from Field-Aligned Potential Drops

A search for the plasma processes associated with perpendicular ion heating

Laboratory observations of ion cyclotron waves associated with a double layer in an inhomogeneous magnetic field

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