Zapevalov Vladimir Evgen'evich

Theoretical and experimental study of electron-wave processes in powerful electronic devices, as well as the development of gyrotrons for controlled thermonuclear fusion, spectroscopy and technological applications.

• 1972 - graduated from Gorky State University (GSU - now Nizhny Novgorod State University - NNSU), faculty of radiophysics, qualification "radiophysics". The diploma thesis was carried out at the Leningrad Institute of Nuclear Physics of Academy of Sciences of the USSR (LINP), in Gatchina, on the subject of studying the phase transition in magnetically diluted palladium-iron alloys using slow polarized neutrons.
• 1985 - defended his PHD dissertation.
• 2008 - defended his doctoral dissertation. Doctoral dissertation is devoted to the problems of increasing the efficiency of generating powerful gyrotrons.

Supervising by qualification works of students and graduate students of NNSU

After graduating from GSU (now Nizhny Novgorod State University - NNSU), he worked at Gorky State University (Nizhny Novgorod State University), and from 1985 to the present moment has been working at the Institute of Applied Physics of Academy of Sciences of the USSR (currently IAP RAS). Head of the laboratory of gyrotrons for controlled thermonuclear fusion. Scientific visits to various countries and to many universities and institutes, the longest and repeated visits to VARIAN (now CPI - USA), to General Atomic (USA), Max-Planck-Institut für Plasmaphysik (IPP, Garching, Germany), Frankfurt University (Frankfurt Main, Germany), Japan Institute of Atomic Research (JAERI-Japan), Fukui University (Japan), Karlsruhe Institute of Technology (KIT, Karlsruhe, Germany).

USSR VDNKh medal 2011 - Laureate of the RF Government Prize in the field of science and technology. Management and participation in grants from INTAS, RFBR, RSF

Key achievements (in collaboration with various co-authors)

1. A method for analyzing the interaction of modes in gyroscopes is proposed, based on the study of mode maps (magnetic field generation regions).
2. It was shown that competition from the modes synchronous with the electron beam at the main cyclotron resonance is the main factor limiting the output radiation power at the second harmonic of the gyrofrequency. The suppression of these parasitic modes significantly increases the stability of oscillations and contributes to an increase in the power of gyrotrons at the second harmonic.
3. The effect of cathode instability in magnetron-injection guns of gyrotrons was discovered and recommendations were developed to suppress its development.
4. A technique has been developed for the experimental study of helical electron beams using an additional diaphragm placed in an increasing magnetic field. The technique allows one to compare the characteristics of beams in the presence and absence of electrons reflected from a magnetic mirror and trapped in an adiabatic trap. It has been demonstrated that the reflected electrons have a significant effect on the characteristics of the generated beams. The developed technique was used to optimize the electron-optical systems of powerful gyrotrons.
5. Suggested (2 A.S.) and studied gyrotrons with additional absorbing or emitting electron beams (multipath gyrotrons), in which a high degree of electronic mode selection is realized. Using an additional emitting beam, an output power of about 1 MW at the second cyclotron harmonic was obtained.
6. It has been experimentally and theoretically shown that the use of gyrotrons on coupled mode transformation resonators (CPTM) not only provides a high degree of mode selection, but also increases the efficiency and reduces the level of ohmic losses in the resonator. The further development of the concept of SRTM in the form of multi-stage and echelet resonators is proposed.
7. The possibility of selective mode excitation at the third to fifth harmonics of the gyrofrequency when using an axial helical electron beam in a gyrotron even at moderate particle energies has been experimentally demonstrated. The gyrotron was used with a magnetic system with a field of about 1 T based on a permanent magnet with an additional coil.
8. The effective and stable operation of gyrotrons at very high volume cavity (resonator) modes (for example, TE25.10) has been demonstrated. The use of such high modes made it possible to provide a megawatt level of continuous generation power.
9. The efficiency of using the recovery of residual electron energy in high-power gyrotrons (CPD- collector) has been demonstrated. Recovery significantly increases efficiency and at the same time simplifies the solution to the problem of cooling collectors and power supplies. For the coaxial gyrotron, a “natural” recovery scheme is proposed that does not require a design change and is promising for increasing the efficiency and controlling the parameters of the output radiation.
10. Proposed and developed prototypes of high-efficiency long-pulse and continuous gyrotrons of the millimeter wavelength range, which are widely used in plasma research and the development of promising technological processes.
11. The concept of technological gyrotron complexes based on gyrotrons at the 2nd harmonic of the gyrofrequency is proposed and a head sample of the complex (30 GHz / 10 kW) is developed. The complex was delivered to the Technological Center of Karlsruhe (now KIT), (Germany) where it has been used for technological research for more than 20 years.
12. It has been shown theoretically and experimentally that relativistic gyrotrons, contrary to a common misconception, can have high efficiency. On this basis, relativistic gyrotrons of the cm and mm ranges of the multi-megawatt power level are created.
13. A 300 GHz gyrotron with an output power of about 3 kW in continuous mode (2005) for operation in a “dry” cryomagnet with a magnetic field of 12 T was created (together with company GYKOM Ltd.), which had no analogues at the time of creation. The gyrotron was delivered to the University of Fukui (Japan) where it was used for technological and biomedical research.
14. The effect of after cavity (post-resonator) interaction in gyrotrons (ACI) was discovered and its influence on the efficiency of gyrotrons, including the recovery of the residual energy of the spent electron beam, was studied.
15. Created (jointly with company GYKOM Ltd.) the world's first gyrotron complex for DNP NMR based on 258/264 GHz gyrotron at the second harmonic of the gyrofrequency with an output power of about 100 W with high stability of the output characteristics in continuous regime (2009). The complex was delivered to the University of Frankfurt am Main (Germany) where it is used up to now for NDP NVR chemical and biomedical research.
16. New collector options are proposed (2 patents) for high-power electronic devices with increased scanning speed.