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).

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

This report gives an update of the worldwide experimental achievements in the development of long-pulse gyrotron oscillators for fusion plasma heating, plasma diagnostics and materials processing. In addition, this work gives a short overview of the present development status of coaxial-cavity multi-megawatt gyrotrons, gyrotrons for technological and spectroscopy applications, relativistic gyrotrons, quasi-optical gyrotrons, cyclotron autoresonance masers, gyro-amplifiers, gyro-BWO's, free electron masers and of vacuum windows for such high-power mm-wave sources.

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State-of-the-Art of High Power Gyro-Devices and Free Electron Masers. Update 2011. (KIT Scientific Reports ; 7606)

Dieser Bericht geht auf den experimentellen Stand von Hochleistungs-Gyrotron-Rohren fur verschiedene Anwendungen ein. Auserdem wird uber frequenzdurchstimmbare Gyrotrons, Multi-MW-Gyrotrons mit koaxialem Resonator, Gyrotrons fur technologische und spektroskopische Anwendungen, relativistische Gyrotrons, Zyklotron-Autoresonanz-Maser, Gyroklystrons, Gyro-TWT-und Gyrotwystron-Verstarker, Gyro-RWO, Gyro-Harmonische-Konvertoren Gyro-Peniotrons, Magnicons, und Frei-Elektronen-Maser berichtet.

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State-of-the-Art of High Power Gyro-Devices and Free Electron Masers. Update 2015 (KIT Scientific Reports ; 7717)

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 generation of energy by controlled thermonuclear fusion. The maximum pulse length of commercially available 1 MW gyrotrons employing synthetic diamond output windows is 5 s at 110 GHz (CPI and JAERI-TOSHIBA), 12s at 140 GHz (FZK-CRPP-CEA-TED) and 9 s at 170 GHz (JAERI-TOSHIBA), with efficiencies slightly above 30%. Total efficiencies of 45-50 % have been obtained using single-stage depressed collectors (for energy recovery). The energy world record of 160 MJ (0.89 MW at 180 s pulse length and 140 GHz) at power levels higher than 0.8 MW has been achieved by the European FZK-CRPP-CEA-TED collaboration at FZK where the pulse length restriction to 180 s is due to the HV power supply at I b e a m m 40 A. At lower beam current (I b e a m = 26 A) it was even possible to obtain 506 MJ (0.54 MW for 937 s). The longest shot lasted for 1300 s at 0.26 MW output power. These very long pulses were limited by a pressure increase in the tube. A maximum output power of 1.2 MW in 4.1 s pulses was generated with the JAERI-TOSHIBA 110 GHz gyrotron. The Russian and the Japan 170 GHz ITER gyrotrons achieved 0.54 MW at 80s pulse duration and 0.5 MW at 500 s, respectively. Diagnostic gyrotrons deliver Pout = 40 kW with T = 40 μs at frequencies up to 650 GHz (η ≥ 4%). Gyrotron oscillators have also been successfully used in materials processing. Such technological applications require gyrotrons with the following parameters: f ≥ 24 GHz, Pout = 4-50 kW, CW, η ≥ 30%. This paper gives an update of the experimental achievements related to the development of high power gyrotron oscillators for long pulse or CW operation and pulsed gyrotrons for plasma diagnostics. In addition, this work gives a short overview of the present development status of coaxial cavity gyrotrons, gyrotrons for technological applications, relativistic gyrotrons, quasi-optical gyrotrons, fast- and slow-wave cyclotron autoresonance masers (CARMs), gyroklystrons, gyro-TWT amplifiers, gyrotwystron amplifiers, gyro-BWO's, gyropeniotrons, magnicons, gyroharmonic converters, free electron masers (FEMs) and of vacuum windows for such high-power mm-wave sources. The highest CW powers produced by gyrotron oscillators, gyroklystrons and FEMs are, respectively, 340 kW (28 GHz), 10 kW (94 GHz) and 36 W (15 GHz). The IR FEL at the Thomas Jefferson National Accelerator Facility obtained a record average power of 4 kW at 5.7 μm.

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State-of-the-art of high power gyro-devices and free electron masers. Update 2004

STATUS DER ENTWICKLUNG VON HOCHLEISTUNGS-GYRO-ROHREN UND FREI-ELEKTRONEN-MASERN - STAND: ENDE 2007
Gyrotronoszillatoren (Gyromonotrons) werden vorwiegend als Hochleistungsmillimeterwellenquellen fur Elektron-Zyklotron-Resonanzheizung (ECRH), Elektron-Zyklotron-Stromtrieb (ECCD), Stabilitatskontrolle und Diagnostik von magnetisch eingeschlossenen Plasmen zur Erforschung der Energiegewinnung durch kontrollierte Kernfusion eingesetzt. Die maximale Pulslange von kommerziell erhaltlichen 140 GHz, 1 Megawatt Gyrotrons mit Austrittsfenstern aus kunstlichem Diamant ist 30 min. (CPI und Europaische FZK-CRPP-TED-CEA Zusammenarbeitsgemeinschaft). Die Weltrekordparameter des europaischen 140 GHz-Gyrotrons sind: 0,92 MW Ausgangsleistung bei 30 min. Pulslange, 97,5% Gaussche Modenreinheit und 44% Wirkungsgrad mittels eines Kollektors mit einstufiger Gegenspannung zur Energieruckgewinnung. Eine maximale Ausgangsleistung von 1,2 MW bei 4,1 s Pulslange wurden mit dem JAEA-TOSHIBA 110 GHz Gyrotron erzeugt. Das japanische 170 GHz ITER-Gyrotron halt den Energieweltrekord mit 2,16 GJ (0,6 MW, 60 min.) und den Wirkungsgradrekord mit 55% bei 1 MW, 800 s fur Rohren mit einer Ausgangsleistung hoher als 0,5 MW. Das russische 170 GHz ITER-Gyrotron erreichte 0,64 MW bei nahezu 300 s Pulslange. Russische Gyrotrons zur Plasmadiagnostik oder fur spektroskopische Anwendungen arbeiten bei Frequenzen bis zu 650 GHz bei Pout = 40 kW und τ = 40 μs (η > 4%) und mit Pout = 1,5 kW bei 1 THz (η = 2,2%). Gyrotronoszillatoren finden jedoch auch in der Materialprozestechnik erfolgreich Verwendung. Dabei werden Rohren mit folgenden Parametern eingesetzt: f > 24 GHz, Pout = 4-50 kW, CW, η > 30%. In diesem Beitrag wird auf den aktuellen experimentellen Stand bei der Entwicklung von Hochleistungs-Gyrotronoszillatoren fur Langpuls- und Dauerstrichbetrieb sowie von gepulsten Gyrotrons zur Plasmadiagnostik eingegangen. Auserdem wird auch kurz uber den neuesten Stand der Entwicklung von Multimegawatt-Gyrotrons mit koaxialem Resonator, Gyrotrons fur technologische und spektroskopische Anwendungen, relativistischen Gyrotrons, quasi-optischen Gyrotrons, Zyklotron-Autoresonanz-Masern (CARMs) mit schneller oder langsamer Welle, Gyroklystrons, Gyro-TWT-Verstarkern, Gyrotwystron-Verstarkern, Gyro-Ruckwartswellenoszillatoren (BWOs), Gyro-Peniotrons, Magnicon-Verstarkern, Gyro-Harmonische-Konvertoren, Frei-Elektronen-Masern (FEM) und von Vakuumfenstern fur solche Hochleistungsmillimeterwellenquellen berichtet. Die hochsten von Gyroklystrons und FEMs erzeugten CW-Leistungen sind 10 kW (94 GHz) bzw. 36 W (15 GHz). Der IR FEL der Thomas Jefferson National Accelerator Facility erreichte eine Rekord-Durchschnitts-Leistung von 10 kW im Wellenlangenbereich 1-14 μm.

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State-of-the-Art of High Power Gyro-Devices and Free Electron Masers Update 2007

High-power coherent millimeter-wave sources have been extensively studied for many applications including high-resolution radars, millimeter-wave electronic counters measures, material processing, and high- energy particle accelerators. This paper presents some recent experiment results in the development of this gyroklystron at IECAS.

Recent Results in the Development of a Ka-Band Second Harmonic Gyroklystron Amplifier

The design and experiment of a ka-band second harmonic gyroklytron amplifier are reported. The three-cavity 35-GHz second harmonic gyroklystron operates in the TE021 circular electric mode. Based on the numerical simulation, a three-cavity, second harmonic gyroklystron amplifier prototype has been fabricated. Experiments show a peak output power of 212 kW at 35 GHz with a 3-dB bandwidth of 155 MHz (0.44%) when utilizing a 58 kV, 23 A, v⊥/vP = 1.45 electron beam from a magnetron injection gun. The efficiency is approximately 16%, and the gain is about 24 dB.

A Ka-Band Second Harmonic Gyroklystron Amplifier

A quasi-optical mode converter for a W-band TE02 mode gyrotron is designed, fabricated, and tested. The system consists of a step-cut waveguide launcher (cut-in-half circular waveguide) and a doubly curved reflector (an elliptical reflector and a parabolic reflector). Based on the geometric optics principle and the vector diffraction theory, the mode converter is optimized and simulated by using numerical calculations. The simulation results show that the good Gaussian mode is converted from the circular waveguide TE02 mode, and the conversion efficiency is 77.9%. Experimental measurements are performed on a quasi-continuous wave gyrotron operating in the TE02 mode at W-band and show a good agreement with theoretical predictions.

Study of a Quasi-Optical Mode Converter for W-band Gyrotron Oscillator

The design of a ka-band gyrotron traveling wave (gyro-TWT) amplifier is presented. The gyro-TWT amplifier with a severed structure operates in the fundamental harmonic TE01 circular electric mode. The beam-wave interaction is studied by using a particle-in-cell (PIC) code. The simulations predict that the amplifier can produce an output peak power of over 155 kW, 22% efficiency, 23 dB gain, and a 3 dB bandwidth of 2 GHz for a 70 kV, 10 A electron beam with an axial velocity spread Δvz/vz=5%.

Particle simulation of a ka-band gyrotron traveling wave amplifier

The invention discloses a ray representation method of a gyrotron quasi-optical output system, and relates to the microwave technology. The method comprises the following steps of: a) determining an incident light angle; b) selecting the curved surface shape of two mirror reflectors; c) orderly placing the first mirror reflector and the second mirror reflector on an output light path of a gyrotron radiator; d) converting the propagation characteristics of a millimeter wave beam on the first mirror reflector and the second mirror reflector into a light propagation process of a light ray on the first mirror reflector and the second mirror reflector; e) charting the reflected propagation path of the light ray in a first mirror reflector and second mirror reflector conversion system; f) according to the propagation path chart formed in the step e), guiding design and rectification of the curved surface of the reflector of a quasi-optical mode converter, and finishing. The representation method provided by the invention is accurate, simple, practical and low in cost.

Yi-Nong Su

Papers

Recent Results in the Development of a Ka-Band Second Harmonic Gyroklystron Amplifier

A Ka-Band Second Harmonic Gyroklystron Amplifier

Study of a Quasi-Optical Mode Converter for W-band Gyrotron Oscillator

Particle simulation of a ka-band gyrotron traveling wave amplifier

Ray representation method of gyrotron quasi-optical output system