Effects of Ion Temperature and Inertia on Kinetic Alfvén Waves

Kinetic Alfvén wave (KAW) has been an interesting topic for discussion extensively in the fields of labora-tory, space, and astrophysical plasmas. A general dispersion equation is derived from the exact two-fluid model in thisambient magnetic field. For the short wavelength cases of kλi >> 1, where λi = vA/ωci and ωci are the ion inertial lengthand gyrofrequency, respectively, our dispersion relations are appropriate for discussing effects of the ion temperatureand inertia on KAWs. The present results show that both the ion temperature and inertia can affect considerably thebehaviors of KAWs in propagation, resonance, and polarization. In particular, our results may be a great help to un-derstanding some salient features of the low-frequency (in comparison with the ion gyrofrequency ωci) electromagneticfluctuations frequently observed by the FREJA and FAST satellites in the auroral zone of the Earth's ionosphere andmagnetosphere.