Yu.V. Rodin

Bio: Yu.V. Rodin is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Gyrotron & Microwave. The author has an hindex of 5, co-authored 15 publications receiving 92 citations.

Experimental Study of the Pulsed Terahertz Gyrotron with Record-Breaking Power and Efficiency Parameters

Abstract: We describe the results of studying experimentally a high-power (hundreds of kilowatts) pulsed (pulse duration of about 30 μs) subterahertz gyrotron with the generation frequency corresponding to one of the atmosphere transparency windows. The gyrotron with an operating frequency of 0.67 THz, a power of more than 200 kW and an efficiency of 20–25% was used in the experiments on ignition of a localized discharge in a plasma. The paper presents the data about measurements of the temperature field of the emitter, calorimetric measurements of the power and efficiency of the gyrotron, and the design of the quasioptical converter of radiation to a narrow wave beam. The first experiments with the terahertz discharge in a focused wave beam of the gyrotron are briefly described.

High-Efficient Mode Converter for ITER Gyrotron

Abstract: A high-efficiency mode converter of the ITER gyrotron operating mode into the Gaussian wave beam has been developed. It includes an irradiating waveguide with shallow deformation and profiled quasi-optical mirrors to increase the Gaussian content. Low-power tests were carried out with a TE25.10 mode exciter and a mode converter. A prototype of the short-pulsed 170 GHz gymtmn with the new converter was manufactured and tested. Diffraction losses measured inside the tube were less then 2% at the 1 MW power level. A high Gaussian mode content in the output beam has been also demonstrated.

Optically controlled semiconductor microwave modulator with nanosecond response

Abstract: A microwave modulator optically controlled by laser pulses has been theoretically studied, constructed, and tested. Results of numerical simulations performed by the finite-difference method are presented, design parameters are reported, and coincidence between the calculated and experimentally measured characteristics is demonstrated. The switching time of the modulator is about 1 ns, the characteristic energy of control laser pulses sufficient for the optimum switching is 10 mJ, and the range of mechanical tuning of the microwave frequency is about 10% (66–72 GHz). It is experimentally demonstrated that the modulator reliably operates when the control laser radiation parameters vary within broad limits.

Cerenkov relativistic oscillators of coherent electromagnetic radiation with multimode sectioned electrodynamic systems

Abstract: The results of the investigation of some versions of relativistic microwave devices with oversized electrodynamic systems are given. The coherence of the output radiation in the oversized system was achieved by the selective feedback In generators and the selective modulation of the electron beam in amplifiers. In all the versions studied a section of a wide-band TWT was used to amplify the power.

Experimental investigation of powerful 0.67 THz gyrotron with a pulsed solenoid for remote detection of concealed radioactive materials

Abstract: Design and results of experimental tests of a high-power sub-terahertz gyrotron with a pulse solenoid for remote detection of radioactive materials are presented. Operating frequency corresponds to the atmospheric transparency window (0.66–0.67 THz). The 200 kW output power in pulses up to 30 microsecond duration were obtained.

State-of-the-Art of High-Power Gyro-Devices and Free Electron Masers

Abstract: This paper presents a review of the experimental achievements related to the development of high-power gyrotron oscillators for long-pulse or CW operation and pulsed gyrotrons for many applications. In addition, this work gives a short overview on the present development status of frequency step-tunable and multi-frequency gyrotrons, coaxial-cavity multi-megawatt gyrotrons, gyrotrons for technological and spectroscopy applications, relativistic gyrotrons, large orbit gyrotrons (LOGs), quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs), gyroklystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWOs, gyro-harmonic converters, gyro-peniotrons, magnicons, free electron masers (FEMs), and dielectric vacuum windows for such high-power mm-wave sources. Gyrotron oscillators (gyromonotrons) are mainly used as high-power millimeter wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control, and diagnostics of magnetically confined plasmas for clean generation of energy by controlled thermonuclear fusion. The maximum pulse length of commercially available 140 GHz, megawatt-class gyrotrons employing synthetic diamond output windows is 30 min (CPI and European KIT-SPC-THALES collaboration). The world record parameters of the European tube are as follows: 0.92 MW output power at 30-min pulse duration, 97.5% Gaussian mode purity, and 44% efficiency, employing a single-stage depressed collector (SDC) for energy recovery. A maximum output power of 1.5 MW in 4.0-s pulses at 45% efficiency was generated with the QST-TOSHIBA (now CANON) 110-GHz gyrotron. The Japan 170-GHz ITER gyrotron achieved 1 MW, 800 s at 55% efficiency and holds the energy world record of 2.88 GJ (0.8 MW, 60 min) and the efficiency record of 57% for tubes with an output power of more than 0.5 MW. The Russian 170-GHz ITER gyrotron obtained 0.99 (1.2) MW with a pulse duration of 1000 (100) s and 53% efficiency. The prototype tube of the European 2-MW, 170-GHz coaxial-cavity gyrotron achieved in short pulses the record power of 2.2 MW at 48% efficiency and 96% Gaussian mode purity. Gyrotrons with pulsed magnet for various short-pulse applications deliver Pout = 210 kW with τ = 20 μs at frequencies up to 670 GHz (η ≅ 20%), Pout = 5.3 kW at 1 THz (η = 6.1%), and Pout = 0.5 kW at 1.3 THz (η = 0.6%). Gyrotron oscillators have also been successfully used in materials processing. Such technological applications require tubes with the following parameters: f > 24 GHz, Pout = 4–50 kW, CW, η > 30%. The CW powers produced by gyroklystrons and FEMs are 10 kW (94 GHz) and 36 W (15 GHz), respectively. The IR FEL at the Thomas Jefferson National Accelerator Facility in the USA obtained a record average power of 14.2 kW at a wavelength of 1.6 μm. The THz FEL (NOVEL) at the Budker Institute of Nuclear Physics in Russia achieved a maximum average power of 0.5 kW at wavelengths 50–240 μm (6.00–1.25 THz).

Pulsed power-driven high-power microwave sources

Abstract: The advent of pulsed power technology in the 1960s has enabled the development of very high peak power sources of electromagnetic radiation in the microwave and millimeter wave bands of the electromagnetic spectrum. Such sources have applications in plasma physics, particle acceleration techniques, fusion energy research, high-power radars, and communications, to name just a few. This article describes recent ongoing activity in this field in both Russia and the United States. The overview of research in Russia focuses on high-power microwave (HPM) sources that are powered using SINUS accelerators, which were developed at the Institute of High Current Electronics. The overview of research in the United States focuses more broadly on recent accomplishments of a multidisciplinary university research initiative on HPM sources, which also involved close interactions with Department of Defense laboratories and industry. HPM sources described in this article have generated peak powers exceeding several gigawatts in pulse durations typically on the order of 100 ns in frequencies ranging from about 1 GHz to many tens of gigahertz.

High-power gyrotrons for electron cyclotron heating and current drive

Abstract: In many tokamak and stellarator experiments around the globe that are investigating energy production via controlled thermonuclear fusion, electron cyclotron heating and current drive (ECH&CD) are used for plasma start-up, heating, non-inductive current drive and MHD stability control. ECH will be the first auxiliary heating method used on ITER. Megawatt-class, continuous wave (CW) gyrotrons are employed as high-power millimeter (mm)-wave sources. The present review reports on the worldwide state-of-the-art of high-power gyrotrons. Their successful development during the past years changed ECH from a minor to a major heating method. After a general introduction of the various functions of ECH&CD in fusion physics, especially for ITER, Section 2 will explain the fast-wave gyrotron interaction principle. Section 3 discusses innovations on the components of modern long-pulse fusion gyrotrons (magnetron injection electron gun (MIG), beam tunnel, cavity, quasi-optical output coupler, synthetic diamond output window, single-stage depressed collector) and auxiliary components (superconducting magnets, gyrotron diagnostics, high-power calorimetric dummy loads). Section 4 deals with present megawatt-class gyrotrons for ITER, W7-X, LHD, EAST, KSTAR and JT-60SA, and also includes tubes for moderate pulse length machines as, ASDEX-U, DIII-D, HL-2A, TCV, QUEST and GAMMA-10. In Section 5 the development of future advanced fusion gyrotrons is discussed. These are tubes with higher frequencies for DEMO, multi-frequency (multi-purpose) gyrotrons, stepwise frequency tunable tubes for plasma stabilization, injection-locked and coaxial-cavity multi-megawatt gyrotrons, as well as sub-THz gyrotrons for collective Thomson scattering (CTS). Efficiency enhancement via multi-stage depressed collectors, fast oscillation recovery methods and reliability, availability, maintainability and inspectability (RAMI) will be discussed at the end of this section.

Novel Numerical Method for the Analysis and Synthesis of the Fields in Highly Oversized Waveguide Mode Converters

Abstract: A numerical method for the analysis of the fields in highly oversized waveguides is proposed in this paper. This method allows the simulation of the fields on waveguide walls with arbitrary surface deformations in the case that the waveguide is highly oversized, and the wall deformations are shallow and smooth. Combined with the analysis method, an algorithm has been developed for synthesizing the waveguide wall to provide a desired field distribution. As an example, a 309.6-mm-long waveguide launcher has been designed for a 170-GHz coaxial-cavity gyrotron to transform the TE34,19 cavity mode to a fundamental Gaussian distribution. An efficiency of transformation to the desired fundamental Gaussian mode of 96.3% has been obtained at the launcher aperture, whereas the transformation efficiency is just 86% using a conventional dimpled-wall launcher with a length of 660 mm.

Development of THz Gyrotrons at IAP RAS and FIR UF and Their Applications in Physical Research and High-Power THz Technologies

Abstract: In this paper, we present some of the most significant recent results that characterize the state of the art in the development of sub-THz and THz gyrotrons at IAP-RAS and FIR-UF after 15 years of collaboration as well as their applications in various novel and prospective research fields and advanced technologies.