Rapid development of many scientific and technical disciplines, especially in material science and material engineering increases a demand for quick, accurate and cheap techniques of materials investigations. The EPR spectroscopy meets these requirements and it is used in many fields of science including biology, chemistry and physics. For proper work, the EPR spectrometer needs a microwave source, which are reviewed in this paper. Vacuum tubes as well as semiconductor generators are presented such as magnetron, klystron, traveling wave tube, backward wave oscillator, orotron, gyrotron, Gunn and IMPATT diodes. In this paper main advantages of gyrotron usage, such as stability and an increased spectral resolution in application to EPR spectroscopy is discussed. The most promising and reliable microwave source is suggested.

This paper outlines the principle of the DNP-NMR technique. The gyrotron, as a very promising microwave source for NMR spectroscopy, is evaluated. Four factors: power stability, power tuning, frequency stability, and frequency tuning determine the usability of the gyrotron device. The causes of instabilities, as well as the methods of overcoming limitations and extending usability are explained with reference to the theory, the numerical and experimental results reported by gyrotron groups.

In this paper, a simple and fast method relied upon for designing a Vlasov launcher with a helical cut is proposed. The method is based on graphic interpretation of analytical relationships that link wave parameters (EM field mode) to the launcher’s geometrical dimensions. Using the ray tracing method, a simplified graphic analysis may be carried out. The results obtained are not significantly different from those of rigorous full-wave analyzes. The family of normalized curves that is created in the process greatly facilitates the stage of optimizing the geometrical parameters of the Vlasov launcher

The paper explains how to solve the Gyrotron equation system in the Single Mode Time Dependent Approach. In particular, we point out problems encountered when solving these well-known equations. The starting current estimation approach a using time model is suggested. The solution has been implemented in the Matlab code, which is attached to the article.

This survey presents a review of experimental methods relied upon while implementing gyrotron higher mode generation techniques and performing near electromagnetic field measurements in launcher and quasi-optical mode converters. In particular, the paper focuses on low power (cold) testing of gyrotron quasi-optical mode converters outside of the gyrotron, without the presence of high electromagnetic power and electron beams

In this paper, we describe the development and design procedure of the new kind of coaxial TEm,1 modes generator based on ring resonator with coupling apertures. The generator enables excitation of subsequent TEm,1 modes in a cylindrical waveguide. The proposed design method allows to obtain high purity TEm,1 modes. The angular mode number can be chosen by replacing the plate with coupling apertures. Structure and parameters of the generator was optimized using CST-Microwave Studio. The mode generator was fabricated and checked on the test bench in an anechoic chamber. The measured field distributions confirm excitation of the desired TEm,1 modes. A good agreement between simulations and measurements is obtained. The presented mode generator, operating in non-rotating TEm,1 modes, is easy to fabricate, and suitable for cold-test experiments of high power components and devices.