Many-particle charged-particle plasma simulations using spatial meshes for the electromagnetic field solutions, particle-in-cell (PIC) merged with Monte Carlo collision (MCC) calculations, are coming into wide use for application to partially ionized gases. The author emphasizes the development of PIC computer experiments since the 1950s starting with one-dimensional (1-D) charged-sheet models, the addition of the mesh, and fast direct Poisson equation solvers for 2-D and 3-D. Details are provided for adding the collisions between the charged particles and neutral atoms. The result is many-particle simulations with many of the features met in low-temperature collision plasmas; for example, with applications to plasma-assisted materials processing, but also related to warmer plasmas at the edges of magnetized fusion plasmas. >

Particle-in-Cell Charged Particle Simulations, plus Monte Carlo Collisions with Neutral Atoms, PIC-MCC

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

The Ka -band extended interaction klystrons (EIK) have been developed at the Institute of Electronics, Chinese Academy of Sciences (IECAS), to satisfy the requirement for the high-power millimeter-wave sources in scientific researches. In this work, two kinds of high compression electron gun with the solid or hollow beams, the derivative electron optics systems using the compact permanent magnet uniform focusing and the shared efficient interaction circuit based on the multigap ladder cavity, have been studied in detail and well designed through a mass of calculations. After the mechanical design, finely manufacturing, and a series of technical processes, the Ka -band EIK prototype tubes have been successfully built and tested. For the solid beam scheme, the maximum output power achieves 20 kW in the bandwidth of 60 MHz, and, correspondingly, the gain of 53 dB and the efficiency of 24% are observed. The measured −1 and −3 dB bandwidths are about 220 and 350 MHz, respectively. Meanwhile, the beam transmission is excellent, that is over 97% in dc state and over 90% in RF operation. For the hollow beam case, an over 91% dc transmission test has finished.

Demonstration of a High-Power Ka -Band Extended Interaction Klystron

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

This paper presents the conceptual design of a W-band high-harmonic gyrotron oscillator with a permanent magnet system Mode selection, cavity design, beam-wave interaction calculations, electron-optical system, and quasi-optical mode converter output system are described The gyrotron operates at the third harmonic of the electron cyclotron frequency with the beam interacting with a TE02 circular electric mode The permanent magnet system provided the maximum axial magnetic field of ~ 119 T in the cavity region of the gyrotron In the simulations, an output power of 14 kW has been obtained at a beam voltage of 40 kV with beam current of 3 A, corresponding to an efficiency of 117% through optimizing system parameters

Design of a High-Harmonic Gyrotron With a Permanent Magnet System

In this paper, a continuous wave (CW) low-voltage fundamental harmonic W-band gyrotron has been designed and simulated with the help of a particle-in-cell (PIC) software CHIPIC. The output power of 33.4 kW with an electron efficiency 37.1% in the PIC simulation is obtained by the designed conventional gyrotron employing a 30-kV, 3-A electron beam which is produced by a triode magnetron injection gun. In addition, a high-power capacity collector being one of the key components of CW gyrotrons has been evaluated and tested. The peak power density on the collector wall using the spreading electron system is about 390 ${\rm W}/{\rm cm}^{2}$ in the hot test. The CW output power of 15.8 kW is achieved with the condition of a 29-kV, 1.8-A electron beam in the hot-test experiment of the designed prototype.

Wei Gu

Papers

Demonstration of a High-Power Ka -Band Extended Interaction Klystron

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

A Ka-Band Second Harmonic Gyroklystron Amplifier

Design of a High-Harmonic Gyrotron With a Permanent Magnet System

Experiment and Simulation of a W-Band CW 30 kW Low-Voltage Conventional Gyrotron