### ?

## Kinetic Description of a Whistler Wave Propagating in Plasma Along the Magnetic Field

Resonant wave-particle interaction represents one of the most important phenomena that determines

spectra of waves and dynamics of high-energy particles in space plasma. This interaction was studied

most comprehensively for the case in which, with high degree of accuracy, plasma can be divided into two

components: a cold component that determines dispersion properties of waves but does not participate in resonance

interaction and a high-energy component characterized by low density relative to that of the hot component,

so that it has no impact on wave dispersion. On the contrary, high-energy particles participate in resonance

interaction with a wave thereby determining its kinetic collisionless damping (or amplification in the

case of unstable plasma). To calculate the damping or growth rate of the wave, distribution function of highenergy

particles is usually assumed to be specified analytically. It is also assumed that the damping or growth

rate is much smaller than the wave frequency. In the present work, we develop an approach to analysis of linear

resonance interaction of whistler waves propagating along an external magnetic field with high-energy

electrons that allows lifting limitations mentioned above and finding the real and imaginary parts of frequency

at arbitrary relation between them for a wave with a given wave vector. Moreover, the electron distribution

function that is not divided into cold and high-energy components can be specified numerically, e.g., based

on satellite measurements of differential particles fluxes. The developed approach is illustrated using electron

fluxes measured by Van Allen Probe-A and MMS satellites as examples.