The book identifies and fully discloses current trends and approaches in the development of microwave plasma-chemical equipment and technologies based on it. The mathematical theory of diffusion processes and the foundations of the theory of gas discharge plasma in a magnetic field are described, the methods used to solve stochastic differential equations and Fokker-Planck-Kolmogorov equations are described. Generalization and system presentation of experience and results on development of physical and technical bases of new types of microwave plasma devices are given. Results of practical use of developed microwave plasma sources are given.