Interactions of radiation and plasma with matter were studied. In the field of nuclear tracks the research was focused on the developement of new methods for the detection of charged particles and their applications for the study of high energy ion interaction with matter. For this purpose interaction of 12C, 14 N, 16O 20 Ne with tissue like targets were studied. Total charge-changing cross sections and cross sections for the production of B and Be fragments were measured for reaction induced by 110 - 250 MeV/nucleon 12C ions in C, CH2 and H2O targetts. A new semiempirical model for calculation of fragment emission angle in light and heavy ion fragmentation reactions in the energy region ( 200 MeV/nucleon was developed. The detection of fast neutrons with a pair of CR-39 was studied. Neutron radiography was applied for the study of boron distribution is histological sampels and for the study of transport of liquids in building materials. Applicability of mineral Lorandite as a detector of solar neutrinos was studied by neutron induced autoradiography. The same method was used for mapping of uranium and phosporus in sedments of Lake Baikal to obtain influence on environmental and geological procesess on antropogenic polution. In the field of plasma physics the response of a weakly magnetized plasma column to the positive potential step applied to an electrode immersed in the plasma perpendicularly to the external magnetic field was investigated. In particular, the time evolution of the electron distribution function and the time evolution of the plasma potential was studied. The electron distribution function with a one-sided planar Langmuir probe under two sets of conditions was measured. Under first set of conditions a fire-rod was formed in the plasma and under the second set the fire-rod could not be formed due to low gas pressure or due to low amplitude of the applied positive potential pulse. The formation of plasma potential in front of a negative electrode immersed in plasma with two populations of negative particles was also studied. Within a kinetic model, the dependence of the double layer formation on the density and temperature ratios of the two negative particle populations was predicted. The existence of the double layer was also confirmed with computer simulations, the values of the parameters agree very well with theoretical predictions. In the frame of the investigations of structural modifications in semiconductors samples of Si, Ge and GaAs with heavy ions were implanted, which caused spatially isolated amorphous zones to grow in the semiconductor crystal structure. Afterwards the recristalisatin process of the zones with energetic electrons was excited, followed by the evolution of crystal defects with a transmission electron microscope. The dependence of the defect-recovering rate on the electron energy and sample temperature were determined. In the area of physics of semiconductor devices we have been able, based upon the ionized cluster beam deposition, ICB, of various metal atoms on the Si substrate, to elucidate the physical processes responsible for the occurrence of the so called excess charge capacitance of metal/semiconductor junction, a long standing open problem. In addition, some particular mechanisms of Fermi level pinning, as a function of metal ions acceleration voltage in ICB deposited Schottky structures taking into account the effect of the local electronic structure, have been proposed. In the frame of investigations of molecular groups in molecular crystals with NMR method we focused our attention on the tunneling process analysis of metilgroups, embedded in the crystal grid. The time evolution of the proton magnetization in a rotational coordinate system were followed. The phenomenon of decoherence, which is of fundamental importance for the understanding of quantum mechanics and for the further research in the field of quantum computers were studied. Decoherence as a