Nonlinear Development of Current-driven Instabilities and 3^He Rich Events in Solar Flares (Gases, Plasmas and Electric Discharges)

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Preferential acceleration of ^3He ions by H cyclotron waves excited via nonlinear effects of strong current-driven instabilities is studied. The plasma is assumed to consist of electrons, H, ^4He and ^3He ions with the abundance of ^3He being very small. First, by means of a two-dimensional, electrostatic, particle simulation code, it is demonstrated that ^3He ions are selectively accelerated by fundamental H cyclotron waves with frequencies ω 〜^^^_ 2Ω_<3He> (Ω_<3He> is the cyclotron frequency of ^3He). These waves grow to large amplitudes in a plasma with the electron temperature parallel to the magnetic field re|| higher than the ion temperature T_H. Next, frequencies and growth rates of H cyclotron waves in a plasma with T_<e‖> > T_H are studied theoretically and numerically. The condition under which the waves with ω 〜^^^_ 2Ω_<3He> become dominant is investigated. It is found that these waves have the greatest growth rates for a large region of the plasma parameters; T_<e‖> > T_H 10 mush be satisfied. It is then suggested that these waves can play an essential role in ^3He rich events in solar flares.
社団法人日本物理学会の論文
2003-05-15