scispace - formally typeset
Search or ask a question
Author

Andrey V. Savilov

Bio: Andrey V. Savilov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Gyrotron & Terahertz radiation. The author has an hindex of 21, co-authored 205 publications receiving 1306 citations. Previous affiliations of Andrey V. Savilov include Joint Institute for Nuclear Research & N. I. Lobachevsky State University of Nizhny Novgorod.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a large orbit gyrotron with a 300 keV, 30 A, 20 ns electron beam has provided selective generation with radiation power from 1.5 MW at fundamental (wavelength of 14 mm) to 100 kW at the fifth cyclotron harmonic (length of 4 mm).
Abstract: A large orbit gyrotron with a 300 keV, 30 A, 20 ns electron beam has provided selective generation with radiation power from 1.5 MW at fundamental (wavelength of 14 mm) to 100 kW at the fifth cyclotron harmonic (wavelength of 4 mm). The next experiment with a unique electron beam (250 keV, 18 A, 10 /spl mu/s, 0.6 mm in diameter) is in progress.

95 citations

Journal ArticleDOI
TL;DR: In this article, a pulsed fundamental-harmonic gyrotron with MW-level power at 0.3 and a CW kW-level third cyclotron with a frequency of 0.4
Abstract: Powerful gyrotrons with radiation frequencies in the range 0.33–0.65 THz were demonstrated at the IAP as early as in the 1970–1980s. This trend has recently been renewed in connection with a significant increase in interest in terahertz frequency range. In the course of new experiments, the radiation frequency of pulsed gyrotrons was increased up to 1.3 THz and 1 THz at the fundamental and third cyclotron harmonics, respectively. In addition, gyrotrons operated in CW regime with a frequency of 0.3 THz for technological applications (in collaboration with the University of Fukui, Japan) and 0.26 THz for the dynamic nuclear polarization at a high-field NMR were implemented. Designs of a pulsed fundamental-harmonic gyrotron with MW-level power at 0.3 THz and a CW kW-level third-harmonic gyrotron with a frequency of 0.4 THz are currently developed. Estimates show that modern techniques for the creation of strong magnetic fields now make it possible to realize gyrotrons with an operating frequency at least up to 1–1.5 THz. Such generators utilize a relatively low particle energy and can provide higher average power than the existing FELs.

54 citations

Journal ArticleDOI
TL;DR: In this article, the Smith-Purcell free electron laser (FEL) was used to obtain powerful millimeter/ sub-millimeter stimulated radiation from a high-current, moderately relativistic electron beam.
Abstract: Frequency multiplication in the Smith-Purcell free electron laser (FEL) as a way to obtain powerful millimeter/ sub-millimeter stimulated radiation from a high-current, moderately relativistic electron beam is studied. It is shown that the main mechanism that provided the multiplication is mutual scattering of low-frequency and high-frequency waves on the electron beam. The use of this mechanism can provide the power level of tens of megawatts and the possibility of a relatively broadband (few percent) frequency tuning.

48 citations

Journal ArticleDOI
TL;DR: In this article, a design of a third-harmonic terahertz gyrotron is studied in detail and discussed, and the use of a sectioned microwave system provides an enhancement of the output rf power by several times along with the halving of the Ohmic losses.
Abstract: High-harmonic large-orbit gyrotrons require long-length operating cavities because of both a weak electron-wave coupling and relatively low electron currents. Since diffraction Q factors of such cavities are very high, a large fraction of the radiated power is dissipated in Ohmic losses. A sectioned klystronlike cavity can be a way to combine a long electron-wave interaction region with a relatively low diffraction Q factor. In this paper, a design of a third-harmonic terahertz gyrotron is studied in detail and discussed. As compared to a regular cavity, the use of a sectioned microwave system provides an enhancement of the output rf power by several times along with the halving of the Ohmic losses.

43 citations

Journal ArticleDOI
TL;DR: In this article, the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields is proposed.
Abstract: It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.

43 citations


Cited by
More filters
01 Jan 2017
TL;DR: The 2017 roadmap of terahertz frequency electromagnetic radiation (100 GHz-30 THz) as mentioned in this paper provides a snapshot of the present state of THz science and technology in 2017, and provides an opinion on the challenges and opportunities that the future holds.
Abstract: Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.

690 citations

Journal ArticleDOI
TL;DR: The electron cyclotron maser (ECM) as mentioned in this paper is based on a stimulated cyclogron emission process involving energetic electrons in gyrational motion, which constitutes a cornerstone of relativistic electronics.
Abstract: The electron cyclotron maser (ECM) is based on a stimulated cyclotron emission process involving energetic electrons in gyrational motion. It constitutes a cornerstone of relativistic electronics, a discipline that has emerged from our understanding and utilization of relativistic effects for the generation of coherent radiation from free electrons. Over a span of four decades, the ECM has undergone a remarkably successful evolution from basic research to device implementation while continuously being enriched by new physical insights. By delivering unprecedented power levels, ECM-based devices have occupied a unique position in the millimeter and submillimeter regions of the electromagnetic spectrum, and find use in numerous applications such as fusion plasma heating, advanced radars, industrial processing, materials characterization, particle acceleration, and tracking of space objects. This article presents a comprehensive review of the fundamental principles of the ECM and their embodiment in practical devices.

492 citations

Journal ArticleDOI
TL;DR: In this article, the authors present state-of-the-art passive high-power microwave components for applications in microwave systems for RF plasma generation and heating, plasma diagnostics, plasma and microwave materials processing, spectroscopy, communication, radar ranging and imaging, and for drivers of next generation high-field-gradient electron-positron linear colliders.
Abstract: This review discusses the present state-of-the-art of passive high-power microwave components for applications in microwave systems for RF plasma generation and heating, plasma diagnostics, plasma and microwave materials processing, spectroscopy, communication, radar ranging and imaging, and for drivers of next generation high-field-gradient electron-positron linear colliders. The paper reports on high-power components for overmoded high-power transmission systems such as smooth-wall waveguides, HE/sub 11/ hybrid mode waveguides and quasi-optical TEM/sub 00/ beam waveguides. These include various types of mode converters, polarizers, cross-section tapers, bends, mode selective filters, pulse compressors, DC-breaks, directional couplers, beam combiners and dividers, vacuum windows, and instruments for mode analysis. Problems of ohmic attenuation and unwanted conversion to parasitic modes are discussed in detail and rules for alignment requirements are given. In the case of waveguide transmission, this review mainly concentrates on circular waveguide components but also deals with rectangular waveguide.

281 citations

Journal ArticleDOI
TL;DR: A review of the development of high-power gyrotron oscillators for long-pulse or CW operation and pulsed gyrotrons for many applications can be found in this article.
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).

279 citations

01 Aug 1986
TL;DR: In this article, a comprehensive theory of the cyclotron resonance maser (CRM) interaction in a circular waveguide is presented, and the conditions for maximum temporal and spatial growth rates are shown.
Abstract: This paper presents a comprehensive theory of the cyclotron resonance maser (CRM) interaction in a circular waveguide. The kinetic theory is used to derive the dispersion relationships for both TE and TM modes. The TE mode case has been investigated by several authors, but there has been comparatively little work on the TM mode case. However, the TM mode interaction competes effectively with the TE mode interaction at relativistic electron energies. The conditions for maximum temporal and spatial growth rates are shown. The TM mode growth rates are found to vanish when the RF wave group velocity equals the beam axial velocity (‘grazing incidence’). The single particle theory is used to derive a compact set of self-consistent non-linear equations for the TE and TM mode interactions. These equations are particularly appropriate for the cyclotron auto-resonance maser (CARM) regime but applicability extends to other regimes as well. The conditions for optimum efficiency are investigated for oscillator and amp...

186 citations