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.

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.

The problems of reflection and transmission of a whistler wave incident in the nighttime ionosphere from above are considered. Numerical solutions of the wave equations for a typical condition of the lower ionosphere are found. The energy reflection coefficient and horizontal wave magnetic field on the ground surface are calculated. The obtained results are important for analysis of the ELF–VLF emission phenomena observed from both the satellites and the ground-based observatories.

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.