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).

/pdf/state-of-the-art-of-high-power-gyro-devices-and-free-5avfirj4z9.pdf

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

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 P out  = 210 kW with τ  = 20 μs at frequencies up to 670 GHz ( η  ≅ 20%), P out  = 5.3 kW at 1 THz ( η  = 6.1%), and P out  = 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, P out  = 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).

/pdf/state-of-the-art-of-high-power-gyro-devices-and-free-3dd9d7und5.pdf

State-of-the-art of high power gyro-devices and free electron masers update 1995

Gyrotron oscillators (gyromonotrons) are mainly used as high power millimeter wave sources foi 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 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 0.5 MW at 80s pulse duration and 0.3 MW at 60s, respectively. Diagnostic gyrotrons deliver Pout = 40 kW with τ = 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 = 10-50 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 (3.1 μ m) FEL at the Thomas Jefferson National Accelerator Facility obtained a record average power of 2.13 kW with an efficiency of 3.5% (with energy recovery).

/pdf/state-of-the-art-of-high-power-gyro-devices-and-free-jsqotznrt4.pdf

State-of-the-art of high power gyro-devices and free electron masers update 2002

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 140 GHz, megawatt-class gyrotrons employing synthetic diamond output windows is 30 minutes (CPI and European FZK-CRPP-CEA-TED collaboration). The world record parameters of the European megawatt-class 140 GHz gyrotron are: 0.92 MW output power at 30 min. pulse duration, 97.5% Gaussian mode purity and 44% efficiency, employing a single-stage depressed collector for energy recovery. A maximum output power of 1.2 MW in 4.1 s pulses was generated with the JAEA-TOSHIBA 110 GHz gyrotron. The Japan 170 GHz ITER gyrotron holds the energy world record of 2.88 GJ (0.8 MW, 60 min.) and the efficiency record of 55% at 1 MW, 800 s for tubes with an output power of more than 0.5 MW. The Russian 170 GHz ITER gyrotron achieved 0.83 MW with a pulse duration of almost 203 s. Russian gyrotrons for plasma diagnostics or spectroscopy applications deliver Pout = 40 kW with τ = 40 μs at frequencies up to 650 GHz (η > 4%), Pout = 1.5 kW at 1 THz (η = 2.2%), and Pout = 0.5 kW at 1.3 THz (η = 0.7%). 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 multi-megawatt gyrotrons, gyrotrons for technological and spectroscopy applications, relativistic gyrotrons, quasi-optical gyrotrons, fastand 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 gyroklystrons and FEMs are, respectively, 10 kW (94 GHz) and 36 W (15 GHz). 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 obtained a maximum average power of 0.5 kW in the wavelength range 110-240 μm (2.73-1.25 THz). Please send corrections, completions and supplements to manfred.thumm@ihm.fzk.de STATUS DER ENTWICKLUNG VON HOCHLEISTUNGS-GYRO-RÖHREN UND FREI-ELEKTRONEN-MASERN STAND: ENDE 2008

State-of-the-Art of High Power Gyro-Devices and Free Electron Masers Update 2008

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.

/pdf/state-of-the-art-of-high-power-gyro-devices-and-free-1mmeiw5vph.pdf

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

The first TH1506B prototype showing problems of overheating and spurious oscillations, a new modified gyrotron was built During the tests, the extwo peaks, which was never predicted by simulations Various low evel tests were performed on the mode converter with different shapes for the launcher but without real improvement Besides measurements, the use of a new software Surf3D[l] showed that the problem mainly comes from the 3rd mirror whose curvature is too high and not well taken nto account by the calculation This analysis software is based on ntegral equations and the complete 3D modelling alowed to determine a new profile for the 3rd mirror An aluminium model of a new mirror was manufactured and thorough low level tests made at FZK showed that there was no double peakThe next step would consist in building a gyrotron based on this new design, to confirm the simulation and to valdate it for long pulses

Upgrade Of The TH1506B 118 GHz Gyrotron Using Modeing Tools

In this work we discuss how to tune the frequency of a high-power gyrotron. The importance of this problem increases in the case of using gyrotrons in large-size fusion machines. The point is that the magnetic field in large stellarators and tokamaks considerably changes over the distance from the plasma center to its boarder. This means that the resonance condition between the plasma electrons and the gyrotron signal is fulfilled only in a relatively small layer of the plasma. To reach other plasma layers one must either use mechanically steerable mirrors to direct the RF wave to the desired position and to employ the Doppler shift effect, or change the frequency of the source and, hence, the position of the resonance layer in the plasma. It is quite obvious that the second possibility is more attractive, because it reduces the number of mechanically movable parts close to the plasma in a fusion machine and increases reliability of operation of the entire system.

Frequency-step-tunable high-power gyrotron for plasma physics applications

In accordance with the goals of this ITER Task experimental and theoretical investigations on 1 MW, 170 GHz, CVD-diamond gyrotron and torus windows for continuous wave (CW) operation have been continued. Two gyrotron window units were tested in collaboration with the Russian Hometeam. Unfortunately, both window disks cracked after operation at mm-wave power levels around 1 MW and pulse lengths up to 1.5 s. The reasons are only known for the second unit where a sag of the window disk (120-140 μm), introduced by its brazing, led to a static stress of approximately 0.7-0.8 MPa. A third CVD-diamond disk unit does not show any sag. The high power tests are scheduled for January 2002. A CVD-diamond window disk was irradiated with a neutron fluence of almost 10 2 1 n/m 2 and then brazed to two Inconel waveguide cuffs. The window unit has been mounted into a test housing in an evacuated corrugated HE 1 1 waveguide (I.D. = 63.5 mm) and successfully tested in collaboration with the Japanese Hometeam at mm-wave power levels of 0.58 MW (0.2 MW) and pulse length 15 s (132 s). The temperature rises of the disk at a diameter of 65 mm and at the disk water cooling rim were 27°C and 2°C, respectively. Simulation calculations show agreement with the measured temperature rise curves for tanδ = 4.8 10 - 5 and k = 1200 W/mK which reveals that the reduction of the thermal conductivity by a factor of 2 after neutron irradiation was partially removed during the brazing at temperatures above 600°C. A 118 GHz CVD-diamond torus window unit was successfully in collaboration with CES Cadarache at a mm-wave power level of 0.3 MW and pulse durations up to 111 s. Dielectric, thermal and mechanical properties of a series of CVD-diamond window disks manufactured by DeBeers (Charters, UK) and FhG-IAF (Freiburg, D) have been analyzed. The permittivity at room temperature always is e r = 5.67 ′ 0.01 and the loss tangent at the disk centers tanδ = 1- 2 10 - 5 . Only a small variation with temperature has been observed up to 700 K. Surface losses introduced by the brazing process are still being investigated. Irradiation by a neutron fluence of almost 10 2 1 n/m 2 increaded the loss tangent to 4 10 - 5 but did not change e r . Thermal conductivity was found to be strongly reduced (840 W/m K as compared to 1800-2000 W/m K for unirradiated CVD diamond). The mechanical strength (growth face under tension) is 400 (′ 30) MPa and has not been weakened by the neutron irradiation mentioned above.

ITER ECRF window development: CVD-Diamond Window

Within the European Community the development of high power gyrotrons in continuous wave (CW) operation is in progress since several years in a joint collaboration between research centers with an industrial partner. In particular, the development of a 1 MW, CW, 140 GHz gyrotron for use at the stellarator Wendelstein 7-X has been successfully finished. A first series has already been delivered and tested. With that tube, an output power of 1000 kW has been achieved in short pulse operation (ms) at an electron beam current of 40 A. For a pulse length of 3 minutes, limited by the available high-voltage (HV) power supply, an output power of 920 kW has been obtained at the same current. At a reduced beam current of 29 A an output power of 570 kW was measured with a pulse length of 1893 s without significant increase of the tube pressure. For application at ITER the development of a 2 MW, CW, 170 GHz coaxial cavity gyrotrons started within an European cooperation. In parallel to the design and manufacturing of a first industrial prototype tube, a short pulse pre-prototype tube has been operated, in order to verify the design of critical components under realistic conditions. Another task at Forschungszentrum Karlsruhe (FZK) is the development of frequency step tunable gyrotrons operating in the range from 105-140 GHz. Such gyrotrons would offer some advantageous in the use of microwave sources for stabilization of current driven plasma instabilities in fusion plasma devices (neoclassical tearing modes: NTM)

Development of multi-megawatt gyrotrons at Forschungszentrum Karlsruhe

Experimental results of the 140 GHz, 1 MW longpurse gyrotron for W7-X

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