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

Abstract

STATE-OF-THE-ART OF HIGH POWER GYRO-DEVICES AND FREE ELECTRON MASERSAt present, gyrotron oscillators are mainly used as high power millimeter wave sources for electron cyclotron resonance heating (ECRH) and diagnostics of magnetically confmed plasmas for generation of energy by controlled thermonuclear fusion. 140 GHz gyrotrons with output power Pout = 0.58 MW, pulse length 't = 2.0 s and efficiency 11 = 34 % are commercially available. Diagnostic gyrotrons deliver P out = 40 kW with 't = 40 J-lS at frequencies up to 650 GHz (11 2_ 4 %). Recently, gyrotron oscillators have also been successfully used in matedal processing and plasma chemistry. Such technological applications require gyrotrons with the following parameters: f 2. 28 GHz , Pout = 10-30 kW, CW, 11 2. 30 %. This paper reports on achievements and problems related to the development of very high power mm-wave gyrotrons for long pulse or CW operation and describes the microwave technological pecularities of the different development steps. In addition, this work gives a short overview of the present development of gyrotrons for technological applications, quasi-optical gyrotrons, cyclotron autoresonance masers (CARMs), gyro-ldystrons, gyro-TWT amplifiers, gyro-BWO's and free electron masers (FEMs). The most impressive FEM output parameters are: Pout = 2GW, 't = 20 ns, 11 = 13 % at 140 GHz (LLNL) and Pout = 15 kW, 't = 20 J-tS, 11 = 5 % in the range from 120 to 900 GHz (UCSB). ENTWICKLUNGSSTAND VON HOCHLEISTUNGS-GYRO-RÖHREN UND FREI-ELEKTRONEN-MASERN Übersiebt Gyrotronoszillatoren werden derzeit vorwiegend als Hochleistungsmillimeterwellenquellen für die Elektron-Zyklotron-Resonanzheizung (ECRH) und Diagnostik von magnetisch eingeschlossenen Plasmen zur Erforschung der Energiegewinnung durch kontrollierte Kernfusion eingesetzt. 140 GHz Gyrotrons mit einer Ausgangsleistung von Pout = 0.58 MW bei Pulslängen von 't = 2.0 s und Wirkungsgraden von • 11 = 34% sind kommerziell erhältlich. Gyrotrons zur Plasmadiagnostik erreichen Frequenzen bis zu 650 GHz bei P out = 40 kW und 't = 40 ~-ts (11 2. 4 %). In jüngster Zeit jedoch finden Gyrotronoszillatoren auch für technologische Prozesse und in der Plasmachemie erfolgreich Verwendung. Dabei werden Röhren mit folgenden Parametern eingesetzt: f 2_ 28 GHz, Pout = 10-30 kW, CW, 11 2. 30 %. In diesem Beitrag wird auf den aktuellen Stand und die Probleme bei der Entwicklung von Hochleistungs-mm-Wellen-Gyrotrons für Langpuls-und Dauerstrichbetrieb sowie auf die mikrowellentechnischen Besonderheiten der einzelnen Entwicklungsphasen eingegangen: Außerdem wird auch kurz über den neuesten Stand der Entwicklung von Gyrotrons für technologische Anwendungen, quasi-optischen Gyrotrons, Zyklotron-Autoresonanz-Masern (CARMs), Gyroklystrons, Gyro-TWT-Verstärkern, Gyro-Rückwärtswellenoszillatoren (BWOs) und Frei-Elektronen-Maser (FEM) berichtet. FEM-Rekordausgangsparameter sind hier: Pout = 2 GW, 't = 20 ns, 11 = 13 % bei 140 GHz (LLNL) und Pout = 15 kW, 't = 20 J-lS, 11 = 5 % im Bereich von 120 bis 900 GHz (UCSB). Contents

Extreme-Ultraviolet Light Source for Lithography Based on an Expanding Jet of Dense Xenon Plasma Supported by Microwaves

“…The power deposited into the discharge is ultimately determined by the microwave power delivered from a gyrotron. Most advanced gyrotrons are developed for magnetic nuclear fusion researches [33,34]. Such devices are able to provide megawatt-level power in long pulses (up to 1000 s) or cw mode at selected frequencies between 60 and 170 GHz.…”

“…Few high-power gyrotrons operating at frequencies of 250-670 GHz are being developed [18,19,34]. These devices, providing peak power on the order of 100 kW level in a pulsed mode with the potential of operating in cw mode, are likely most suitable for the proposed EUV-source concept.…”

Design and analysis on a 0.1‐THz second harmonic low‐voltage, low‐current gyrotron with complex cavity

“…As a kind of microwave sources, gyro‐device exhibits outstanding performance on powerful electromagnetic (EM) wave source . Among the existing gyro‐devices, gyrotron is a reliable and efficient device to generate powerful EM wave in the frequency range from millimeter‐wave to THz‐wave, which has been applied in many systems .…”

“…As a kind of microwave sources, gyro‐device exhibits outstanding performance on powerful electromagnetic (EM) wave source . Among the existing gyro‐devices, gyrotron is a reliable and efficient device to generate powerful EM wave in the frequency range from millimeter‐wave to THz‐wave, which has been applied in many systems . Specifically, the radiation at frequency around 0.1 THz, is drawing the attention of the research community as a potential candidate for cancer treatment, medical treatment, and the security applications .…”

Design Modifications in RF Interaction Cavity of a 140 GHZ Gyrotron to Achieve Wide Tunable Bandwidth for DNP NMR Applications

“…It is one class of fast wave device where the phase velocity of the RF wave is comparable with the velocity of light in free space. Gyrotrons widely used in various applications like Electron Cyclotron Resonance Heating, Electron cyclotron Current Drive, material processing which requires very high power of several kW to few MW at higher frequencies [1][2][3][4]. Besides high RF power generations at single or step tunable frequencies, it is suitable to generate a low power level of few watts to tens of watts over a band of frequencies in the millimeter and submillimeter regime.…”