Microinstabilities ??? Instabilities Due to Velocity Space Nonequilibrium

摘要: In this chapter, we treat instabilities that originate from a non-Maxwellian type velocity distribution. Except for special cases (Section 2.5), assume uniform plasma. Because plasmas in space are collision free, they either maintain their original distribution functions or the change slowly due to movement through background magnetic field. Hence function is almost never Maxwellian but rather determined by past history of The can differ basically two different ways. One occurs when has more than humps: example, group streaming particles intermixed with plasma electrons and protons have average velocities. Such treated Section 2.2. other way having an anisotropic force field acts only direction perpendicular field, causing frequency much smaller cyclotron move way. This creates anisotropie respect ambient We discuss associated such 2.3. 2.4 devoted distributions which occur hydromagnetic range (frequencies proton frequency). last section 2.5, partially ionized as relate various ionospheric phenomena. These usually electron-ion stream effect combination density gradient. will see existence gradient modifies instability very interesting dominated