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During last years several new gyrotrons were developed at IAP/GYCOM. Main efforts were spent for development 170GHz/1MW/50%/CW gyrotron for ITER and multi-frequency gyrotrons. The main ITER requirements to a gyrotron have been demonstrated: 1MW power, 1000 seconds pulse duration, 53% efficiency. The gyrotron operation regime of 1.2 MW was found for 100 second pulses. For a multi-frequency gyrotron...
A microwave pulse compressor with a Magictee as an interference switch is studied. In this compressor, the necessary condition for energy storage in the compressor cavity is frequency-independent, so that the operation in different cavity eigenmodes without any mechanical tuning is possible. RF energy storage and release were simulated numerically. Output pulses in the two frequencies, 2.801 and 2...
It is found that the Langmuir-Blodgett (LB) solutions for the space charge limited current density, for both cylindrical and spherical diodes, may be approximated by Japp =(4/9)ε0(2e/m)1/2Ec3/2/D1/2 over a wide range of parameters, where Ec is the surface electric field on the cathode of the vacuum diode and D is the anode-cathode spacing. This dependence is valid whether Ra/Rc is greater than or...
Possible quantum analogues of classical powerful microwave devices (multiwave Cherenkov generator, high-power klystrons, relativistic TWT and BWO) in the interaction of multi streams of charged particles of different sign are discussed. From the standpoint link with the experiment, we have the electron-positron system with collective interaction of many macroscopic groups of particles.
ITER is an international project supported by seven partners: China, Europe, India, Japan, Korea, Russian Federation and USA. Formally established in 2006, construction has started in France, more precisely in Provence. General progress of the project is presented followed by a focus on the RF systems which will provide 40 MW into the plasma, based on systems around 50 MHz and 170 GHz. These systems...
For state of the art cathodes for space applications, a stable operation during the entire life cycle has to be guaranteed. Therefore, at Thales, such devices are characterized thoroughly to assure the level of confidence regarding its long term behaviour. Since the introduction of the MM-type cathode, TED follows strictly a dedicated life test philosophy for space cathodes providing a considerable...
EU is developing a 1 MW cylindrical cavity gyrotron. In the last year the design of the components of the new gyrotron has been finalized while the technological design of the new tube has been defined. In the present paper, the main characteristics of the new EU gyrotron for ITER are presented.
This paper reports on a diamond Brewster angle window which has been used as a vacuum barrier in a 140 GHz step-frequency tunable high power gyrotron. This configuration ensures operation of the gyrotron at different frequencies without reflection of the RF power and provides excellent material properties of CVD diamond in the mm wave range.
Technological and design parts of plasma spraying metal-porous cathodes manufacturing for high-power multi-beam klystron are presented. The samples of cathode assemblies and their parameters are shown when operating in real devices. The results of investigations of the cathodes emission properties in the forced temperature conditions are presented in order to determine the maximum current density...
This program is developing high power windows fabricated from single crystal sapphire that provide superior mechanical properties. A key requirement is a robust surface coating to suppress multipactor emission. This program developed an innovative process that chemically bonds titanium nitride to the surface, providing a significant improvement over sputtered coatings.
In this paper, we examine methods in which plasmas can be used to tune the responses of RF/microwave periodic structures and artificially-engineered materials. In particular, we exploit microwave-induced plasmas created in periodic structures when the power of the incident electromagnetic wave exceeds the breakdown threshold power level. Based on the nature of the plasma created within the unit cell...
Effect of reflection from the output window on the mode competition in gyrotron is investigated using the equations of quasilinear theory for slowly varying amplitudes of the modes with time delayed terms. Stability analysis of single-mode operation shows that the reflections can, under the certain conditions, strongly affect the operation regime.
Plasma assisted microwave devices are unique source for microwave radiation. This paper presents the status for development of X-band Plasma Assisted Slow Wave Oscillator (PASOTRON) of peak power 0.5MW.
This paper presents the latest results from a second harmonic gyro-TWA experiment at Strathclyde University. The experiment uses a helically corrugated interaction region and operates at Ka-band. Simulations have been performed to predict the amplifier gain and bandwidth using linear theory. Amplifier stability margin can be improved with the addition of a sever. A sever has been designed and manufactured,...
This paper presents the electrical designs of interaction cavity and electron gun for triple frequency (170-, 140-, and 127.5 GHz) gyrotron. TE34,10, TE21,11 and TE22,9 modes are selected as the operating mode for 170 GHz, 140 GHz and 127.5 GHz operation of the device, respectively. The design results show more than 1 MW power at all three frequencies.
In this work, an algorithm for coupling external circuit elements to EM PIC simulations is developed. The circuit equation including an external voltage or current source, resistance, inductance, capacitance, and a dynamic load is solved simultaneously with the EM PIC updaters through an instant measured voltage V across the system to obtain the supplied current I for feeding into the system. This...
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