Vol 60, No 1 (2017)

We briefly describe the history of studying the decameter radio wave attenuation by different methods in the midlatitude ionosphere. A new method of estimating the attenuation of HF radio waves in the ionospheric F region near the skip zone boundary is presented. This method is based on an analysis of the time structure of the interference field generated by highly stable monochromatic X-mode radio waves at the observation point. The main parameter is the effective electron collision frequency ν_eff, which allows for all energy losses in the form of equivalent heat loss. The frequency ν_eff is estimated by matching the assumed (model) and the experimentally observed structures. Model calculations are performed using the geometrical-optics approximation. The spatial attenuation caused by the influence of the medium-scale traveling ionospheric disturbances is taken into account. Spherical shape of the ionosphere and the Earth’s magnetic field are roughly allowed for. The results of recording of the level of signals from the RWM (Moscow) station at a frequency of 9.996 MHz at point Rostov are used.

We have ascertained the influence of relativism on the processes and output parameters of a relativistic magnetron. The solution of the electron motion equations in a relativistic plane-geometry magnetron is presented. It is shown that these equations have the form corresponding to the nonrelativistic case, where one uses normalization for the static and high-frequency fields.

We describe the theory of a superluminescent single-pass free electron laser based on the Bogolyubov chain of equations for multiparticle distribution functions. Special choice of the variables eliminates the retardation of interaction. A small parameter (inverse number of particles per signal growth length in the accompanying reference system) for the chain truncation is found. Expansion over this parameter makes it possible to neglect three-particle correlation functions and solve only the equations containing a single-particle distribution function and two-particle correlation functions. The calculation results are in good agreement with the conclusions based on the previously developed quasilinear theory.

We synthesize the quasilikelihood, maximum-likelihood, and quasioptimal algorithms for estimating the moments of appearance and disappearance of a radio signal with an arbitrary shape of the envelope function and unknown amplitude and initial phase. Asymptotic characteristics of the operation efficiency of the synthesized algorithm are found.