The paper discusses the excitation of monochromatic ELF/VLF electromagnetic waves produced by HF heating facility currents in the nighttime ionosphere. The ground-based magnetic field is predominantly located under the source, and the wave has right-hand polarization typical for a whistler but left-hand polarization at large distances from the source. About half of the source energy propagates upward, and approximately 20 % propagates to the Earth–ionosphere waveguide.

The paper discusses a problem concerned with the excitation of chorus with small wave normal angles along the external magnetic field in the magnetosphere. We examine the realisation of the beam pulse amplifier mechanism of chorus excitation without strong anisotropy of the plasma particle distribution function in the density ducts with refractive reflection. It is shown that in the ducts, discrete spectral elements of chorus can be excited at close to half of the electron cyclotron frequency.

A VLF chorus is a very intense electromagnetic plasma wave that is naturally excited as a succession of discrete emissions near the magnetic equatorial plane outside the plasmasphere. We introduce a mechanism of chorus excitation under conditions when known mechanisms become ineffective. This kind of excitation is related to the amplification of short electromagnetic pulses from the noise level even in a stable plasma. Obtained results can explain some important features of the chorus emissions.

We propose a simple explanation of the prolonged existence of pancake-like electron velocity distributions in the radiation belts. The pancake-like distribution function is characterized by a longitudinal particle velocity (along the magnetic field) of the order of the thermal velocity of the background plasma. The parameters of the tablet-like distribution function are refined. The stability of these distributions is examined.