Publication Date:
2013-05-18
Description:
[1] Kinetic Alfvén waves (KAWs) can play an important role in the energization of plasma particles and the formation of filamentous structures, which commonly are encountered and frequently accompanied by field-aligned currents in various magneto-plasmas, such as laboratory, auroral, and coronal plasmas. Based on a low-frequency kinetic dispersion equation in frequency ω 〈 ω ci (the ion cyclotron frequency), KAW instability driven by a field-aligned current, which is carried by the field-aligned drift of electrons at velocity V D , is investigated in a low- β plasma of β 〈 Q ≪ 1, where β is the kinetic-to-magnetic pressure ratio and Q (≡ m e / m i ≪ 1) is the mass ratio of electrons to ions. An instability condition and the corresponding growth rate are obtained, which depends on the plasma β parameter as well as the drift velocity V D . The results show that the KAW instability occurs in the perpendicular wave-number range of , in which the growth rate reaches its maximum at for fixted V D and β . As V D increases, this growing wave-number range widens and the growth rate increases, but the maximal-growing wavenumber decreases. On the other hand, as the plasma β parameter decreases, the growing wave-number range also widens, and the maximal-growing wavenumber and growth rate both increase. These results have potential importance in understanding the physics of the electric current dissipation and plasma active phenomena since the field-aligned current is one of the most active factors in space and astrophysical plasmas.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
Permalink
