Skoryk A. Fine structure of pulsar radiation in the decametre wave range

The thesis is dedicated to the study of radio emission parameters of the closest to Earth pulsars in the decameter wave range. In the thesis a novel approach which uses short pulsar pulses as magnetosphere probes to spatially resolve the radiation region. Though the pulse radiation is broadly used as probes, but more frequently for interstellar medium. In this work it is shown that to probe fast fluctuations of pulsar plasma only short pulses are required. They allows to separate propagation effects that appear in different parts of the propagation medium. The parameters of pulsar radiation under consideration in the thesis that are used for pulsar magnetosphere resolving includes the coherence time of fine structure, the precise dispersion measure parameter and the precise scattering time constant. In the thesis results of processing of observational pulsar data obtained with UTR-2 decameter radio telescope in wave form registration mode with extremely high time resolution are given. The anomalously intense pulses of pulsars J0243+6257, J0814+7429 and J0953+0755 are analyzed. The novel methods of propagation effects removal, namely accelerated method of dispersion delay compensation for both coherent and postdetection algorithms and advanced methods of fine structure search that are based on increasing of contrast of intensity correlation functions. These methods can be applied to a broad variety of radio astronomy problems related to a pulsed radiation sources. They can be used in a wide frequency range and in decameter wave range they give significant advantages. Results obtained in the thesis are novel and expand frequency bounds of research of the fine structure and the scattering parameters of pulsar radiation. It is shown how pulsar location in the Milky Way affects the pulse scattering and limits minimal possible scale of observable fine structure. The unique effect of fast dispersion measure change in ultra short times inside individual pulse is discovered. This effect can be observed for closest to Earth pulsars in decameter wave range due to its distinctive features. The fast dispersion measure variation gives opportunity to resolve a pulsar magnetosphere in depth and estimate height of emission region from the neutron star surface. Also characteristic scales of pulsars radiation fine structure are obtained, which are used for linear sizes of the radiation zones estimation, in this way pulsar magnetospheres are resolved in longitude.