The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, we have presented the simulation results on sheet beam electron gun and sheet beam transport in a uniform magnetic field. It is shown that the sheet beam with size 4.6 mm×0.4 mm, generated by the electron gun with 20 kV, 560 mA, can stably pass through the beam tunnel with transverse size 6 mm×1 mm and the length 120 mm in a uniform magnetic field.
A good quality graphene is transferred onto honeycomb-like CNTs arrays with inner supporting CNTs. The efficient field emission is demonstrated due to a high aspect ratio protrusions and graphene crack edges. A high efficient current density about 1.2 mA/cm2 at threshold electric field of 7.8 V/μm with a turn-on electric field of 1.8 V/μm at the current density of 10 μA/cm2 is observed due to high...
The Recirculating Planar Magnetron (RPM) is a crossed-field device which presents numerous potential advantages in generating High Power Microwaves (HPM). A 12-cavity, conventional-polarity, 1-GHz RPM model has been experimentally designed and tested at a −300 kV, 0.3–0.5 microsecond pulselengths and a 0.2 T axial magnetic field. The experimental results and future concepts are under investigation.
The reasons of limitations in field emitter implementation in powerful RF tubes are investigated, overcoming ways are discussed. The results of electron beam optic system (EOS) design with planar type matrices of field emission cathodes and intense beams with power above 100 kW in CW mode are presented.
A sealed off magnetron injection gun (MIG) collector module for 42 GHz 200 kW gyrotron has been developed. The paper reports the high voltage and beam-emission test result. In addition, the current-voltage characteristics at different heater wattage are also discussed from recent tests.
In this paper, the design and optimization of a V-band helix TWT is carried out and prototype tubes have been assembled. The test results show that the output power of the TWT is over 15W with the overall efficiency of over 14.5% and a gain of over 43dB. The beam transmission experiment shows that a transmission ratio is over 97%.
This paper presents theory and analysis of single-tip field emission and electron beam propagation in the electrostatic focusing fields. It is shown that two gate apertures with a focusing anode allow transport of narrow electron beams over long distances without need for a confining magnetic field. Physical mechanisms of the beam formation, transport, intrinsic emittance with thermal effects, the...
The effects of introducing one or more reflectors inside an axial Vircator are analyzed using CST-Particle Studio® PIC simulation. The power conversion efficiency is shown to be enhanced from 1% to 13% at 3 GHz. The optimum output power is obtained with three reflectors.
We have successfully developed the vacuum-sealed carbon nano-tube (CNT) x-ray tube. The remarkable improvement of field emission properties, life time and stability, was obtained after high temperature brazing process in a vacuum circumstance.
The aim of this paper is to cover the different technologies for pulsed UHF applications, such as the ESS program. The presentation will describe the various technologies with their performance and their limitations or constraints, taking into account also their evolution in the next decade, the Science facilities being used in such time frame.
A Ku-150W space TWT of electronic efficiency(>23.8%), overall efficiency (> 58%j\ phase shifl(<45deg) for frequency fo±0.5GHz has been designed and developed for satellite communication system. This paper presents design and development.
In this work we present a carbon nanotubes electron source assembled with a low cost technique. We used a carbon nanotube cathode that reached the remarkable current density of 0,6 A/cm2. The cathode has been assembled with an external grid in a compact electron source that achieved a maximum output current density of 45 mA/cm2. This represents one the first examples of a CNTs electron source realized...
A macro-focus X-ray tube with CNT emitters was successfully developed. An anode current of 1.15mA was collected when the copper grid gate voltage was 2.7kV. A very small x-ray focal spot size with less than 39μm can be achieved, which could potentially produce very high special resolution X-ray image.
Recent results of a multi-frequency gyrotron and a high frequency power modulation experiment using 170GHz gyrotron are reported. Three frequency oscillations and their Gaussian beam outputs are demonstrated at 170 GHz, 137 GHz and 104 GHz. At present, 0.9 MW/ 70 sec, 1.1 MW/ 5 sec were obtained at 170 GHz. An experiment of 203 GHz oscillation will be conducted from April 2013 in addition to further...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.