Design, Theory, and Simulation of a 46-63 GHz Gyrotron Backward Wave Oscillator PDF Download

Author: Thomas Robert Stephenson
Publisher:
ISBN:
Category :
Languages : en
Pages : 186

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Category :
Languages : en
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A non-linear self-consistent computer simulation code is used to analyze the saturated output of the Gyrotron Backward Wave Oscillator (Gyro BWO) which can be used as a tunable driver for a 250 GHz FEL amplifier. Simulations show that the Gyrotron BWO using a Pierce/Wiggler gun configuration can produce at least 10 kW of microwave power over the range 249 GHz to 265 GHz by varying beam voltage alone.

Author: Liang Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages :

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This thesis is based on the research project of a W-band gyrotron backward wave oscillator (gyro-BWO) using a helically corrugated waveguide which is currently being built and upgraded in the University of Strathclyde. The gyro-BWO was optimally designed through numerical simulations to achieve an output maximum power of ~ 10 kW with a -3 dB frequency tuning range of 84 - 104 GHz. To increase the overall efficiency of the W-band gyro-BWO, an energy recovery system of four-stage depressed collector was designed, numerically optimized and fabricated on the gyro-BWO. Microwave components including the Bragg reflectors, the side-wall coupler, the three-layer microwave window and the pillbox window were designed, simulated and measured to facilitate the practical use of the energy recovery system. This thesis includes the analytically calculated results, the numerical simulations as well as the experimental results of the said components and system. A 14-section Bragg reflector together with the side-wall coupler located at the upstream of the helically corrugated interaction cavity was used to couple the microwave radiation out. This allowed the installation of the depressed collector at the downstream side of the gyro-BWO. The transmission coefficient of the coupler was numerically optimized to achieve -1.0 dB over the frequency tuning range, from 84 - 104 GHz. The Bragg reflector measurement agrees well with the simulation. The input coupler achieves an average -13 dB reflection over the frequency in the measurement. Theoretical analysis of the pillbox type window and multi-layer window based on mode-matching method was carried out. The simulation and optimization of the pillbox window achieved a reflection of less than -15 dB in the whole operating frequency range of 84 - 104 GHz. The three-layer window can achieve less than 30 dB reflection in the frequency range of 84 - 104 GHz in the simulation. A three-layer window and a pillbox window which particularly optimized in frequency range of 90 - 100 GHz (the operating frequency range of the gyro- TW A that shares the same experimental setup as the gyro-BWO) were fabricated. With manufacturing constraints the design of the three-layer window achieved an average -10 dB measured reflection in 84 - 104 GHz and better than -15 dB in 90 - 100 GHz. In the downstream side of the gyro-BWO, another 18-section Bragg reflector was used to reflect the radiation back into the upstream interaction cavity. And the transmission coefficient of -30 dB was obtained in the microwave measurements using a VNA, which means the microwave power leakage was less than 1%. The measurement results agreed well with the simulations. A four-stage depressed collector was designed to recover the energy from the spent electrons. The 3D PlC code MAGIC and a genetic algorithm were used to simulate and optimize the geometry of the electrodes. Secondary electron emissions were simulated and a few emission models were compared to investigate their effects on the overall recovery efficiency and the backstreaming rate for the multistage collector. The optimization of the shape and dimensions of each stage of the collector using a genetic algorithm achieved an overall recovery efficiency of about 70%, with a minimized backstreaming rate of 4.9%. The heat distribution on the collector was calculated and the maximum heat density on the electrodes was 240W/cm2 and the generation of "hot spots" could be avoided. The electric field distribution inside the depressed collector was calculated and the geometries of these electrodes were properly shaped to avoid the voltage breakdown in vacuum.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 47

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Experimental and theoretical analyses, including particle-in-cell computer code simulations, are presented for the Gyrotron Backward Wave oscillator (Gyro-BWO) highpower microwave device. The Gyro-BWO has been designed, constructed, and initially tested as a frequency tunable device. The design has concentrated on a TE01, 4- to 6- GHz annular beam device. The annular beam is produced by the RAMBO pulser, which has a diode voltage of -300 to -800 kV and diode current of 1 to 20 kA. Initial results have shown that the device is operating in the backward wave mode. Initial results have also demonstrated that the device is magnetically tunable; that is, the frequency is tunable by adjusting the magnetic field. A Vlasov-type antenna is used for the extraction of the microwave signal on the diode end of the experiment, with initial power extraction of up to 2 MW ... High power microwave, HPM, Gyro-BWO, Gyrotron, Gyrotron backward wave oscillator.

Author: Craig Ross Donaldson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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This thesis presents the results of a successful W-band gyrotron backward wave oscillator experiment. Three major achievements presented in this thesis are: 1) The design, simulation, construction and operation of a cusp electron gun; 2) The design, simulation, optimisation, construction and experimental measurement of a W-band helically corrugated waveguide and 3) the operation of the world's first W-band gyro-BWO using both a helically corrugated waveguide and a cusp electron gun. Gyro-BWO interaction with a 2nd cyclotron harmonic axis-encircling annular electron beam was observed. The interaction region was constructed through an accurate electroplating method while the designed dispersion characteristics agreed well to the experimental measurements. The loss through the optimised construction method was low, recorded around 1dB through the frequency range of interest. The following work presents the analytical, numerical and experimental investigation of a proof of principle gyro-BWO experiment. The design, simulation and optimisation of a thermionic cusp electron gun that can generate a 1.5A, 40kV axisencircling electron beam are discussed. Simulations showed a high quality electron beam with ~8% velocity spread and ~10% alpha spread. Experiments were conducted using this electron gun and the accelerating voltage pulse, diode current, transported beam current are presented. The electron beam profile was recorded showing a clear axis-encircling beam image from which the electron beam diameter and alpha values can be measured. Microwave radiation was measured over a frequency range of ~91-100GHz with a approximate maximum power of ~0.37kW. Operating over the magnetic field range 1.79T to 1.9T and measured over a range of alpha values this result was very impressive and proved the successful operation of the gyro-BWO.

Author:
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Category : Electrical engineering
Languages : en
Pages : 1532

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Author: Richard G. Carter
Publisher: Cambridge University Press
ISBN: 0521198623
Category : Technology & Engineering
Languages : en
Pages : 843

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Get up-to-speed on the theory, principles and design of vacuum electron devices.

Author:
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Category : Aeronautics
Languages : en
Pages : 1218

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Author: Mark A. Stokes
Publisher: DIANE Publishing
ISBN: 1428911979
Category : Air defenses
Languages : en
Pages : 230

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Conventional wisdom portrays the People's Republic of China (PRC) People's Liberation Army (PLA) as a backward continental force that will not pose a military challenge to its neighbors or to the United States well into the 21st century. PLA writings that demonstrate interest in exploiting the revolution in military affairs (RMA) are dismissed by a large segment of the PLA- watching community as wistful fantasies. The author offers an alternative perspective by outlining emerging PLA operational concepts and a range of research and development projects that appear to have been heavily influenced by U.S. and Russian writings on the RMA. Fulfillment of the PLA's vision for the 21st century could have significant repercussions for U.S. interests in the Asia-Pacific region.

Author: Thomas J. Dolan
Publisher: Springer Science & Business Media
ISBN: 1447155564
Category : Technology & Engineering
Languages : en
Pages : 816

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Magnetic Fusion Technology describes the technologies that are required for successful development of nuclear fusion power plants using strong magnetic fields. These technologies include: • magnet systems, • plasma heating systems, • control systems, • energy conversion systems, • advanced materials development, • vacuum systems, • cryogenic systems, • plasma diagnostics, • safety systems, and • power plant design studies. Magnetic Fusion Technology will be useful to students and to specialists working in energy research.