Demonstration of a high-power long-pulse 140-GHz gyrotron oscillator
ABSTRACT A high-power long-pulse 140-GHz gyrotron oscillator has been designed, constructed, and tested. Key features of the gyrotron include an internal converter to transform the TE28,7,1 operating mode to a Gaussian output beam, a single-stage-depressed collector, and a chemical-vapor-deposition diamond output window. Peak output powers up to 930 kW at 34% efficiency have been demonstrated at 5-ms pulse lengths. Due to power supply limitations, long-pulse operation was not possible for beam currents above 25 A. At 25-A beam current and 500-kW output power, pulse lengths up to 700 s in duration were achieved. The gyrotron has been shipped to the Wendelstein 7-X facility in Greifswald, Germany, where long-pulse demonstrations up to 180s will be carried out at the 930-kW power level.
- SourceAvailable from: Udaybir Singh[Show abstract] [Hide abstract]
ABSTRACT: Microwave occupies a glorious position in the electromagnetic spectrum and in that there are a number of devices in this frequency regime which are capable of high power operations. Among them, gyrotron has proven to be an efficient source for radio frequency (RF) generation at high power level and up to very high frequency. The gyrotron consists of several components like electron beam source, interaction structure, quasi-optical launcher, collector, RF window, magnet system, etc. All the components have their distinct role in the function of the device. Among them, electron beam source also called magnetron injection gun (MIG) is the generator of electron beam and it is very essential that MIG should produce and provide electron beam suitable for the beam-wave interaction at the interaction structure for the effective power growth. The paper presents the introduction of a microwave tube, gyrotron and its components alongwith review of the previous work, the background and the applications. The functions of various components of a gyrotron are discussed with particular highlighting on the electron beam emission from the electron beam source and the beam-wave interaction for power growth in the device. A review on different types of gyrotron electron beam sources is also presented.Journal of Fusion Energy 01/2012; · 1.00 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The availability of high-power microwave sources like gyrotrons makes it now possible to use the Gaussian output RF beam of a conventional gyrotron propagating in free space as an input for the interaction with a sheet electron beam (e-beam) drifting along an external magnetic field, with the aim of generating even higher RF power. Since this interaction is from the beginning in the nonlinear high-efficiency regime, the corresponding field amplitude is adequate to extract a significant amount of power from the high-current e-beam with no need for feedback from the walls of any cavity or resonator. The radiation field excited by the nonlinear perturbed electron motion has been calculated using a self-consistent iterative scheme and is seen to maintain the basic features of the initial RF beam (such as the Gaussian profile), but at a much higher power level as is desired for a fusion reactor.IEEE Transactions on Plasma Science 07/2010; · 0.87 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A theoretical and experimental study on a 94 GHz low-voltage, low-current gyrotron is presented in this paper. In order to obtain stable radiation and make great use of the equipment in the lab, the TE6,2 mode is selected as the operating mode of the desired gyrotron. The efficiency of the electron beam interaction with RF fields under different conditions has been calculated by a code, which is based on the self-consistent nonlinear theory for gyrotrons. The gyrotron is equipped with a single-stage depressed collector and a quasi-optical mode converter. Then, a gyrotron with optimized parameters has been designed, constructed, and tested. An output power of 23 kW is obtained at an accelerating beam voltage of 31.5 kV, a beam current of 1.8 A, and a collector depression voltage of 7.4 kV, corresponding to an overall efficiency of 53%.IEEE Transactions on Electron Devices 01/2013; 60(11):3907-3912. · 2.06 Impact Factor