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The silicon carbide field emission array of microtips on the tops of micropedestals fabricated on original technology was embedded as cathode in planar vacuum diode and its CVC was characterized. The electron beams formed by the cathodes with various dimensions of micropedestals was numerically simulated. The results demonstrate significant influence of micropedestal dimensions on emission current...
In this paper, we study the feasibility and suitability of two beam focusing techniques, i.e., Brillouin-and immersed flow, to be used in a novel device which can be up-scaled in power via increasing the number of beams, and in frequency via reducing the spatial period of the photonic crystal.
In order to apply the traveling wave tubes (TWTs) in the active phased array radar system, new mini-TWT, i.e., multiple electron beam helix TWT (MBTWT) is studied. It is made by putting 3 helixes and electron beams into one metal tube and one PPM focus system. They have common electron gun and collector. The electron gun has a common heater and 3 emitting cathode heads which produce 3 electron beams...
Vacuum electronic (VE) power amplifiers are being developed between 100 GHz and 1 THz. Minimum power goals are 50 watts at 220 GHz, and 100 mW at 670 GHz. These devices will use advanced, high current density cathodes, a folded waveguide as the slow-wave circuit, and a depressed collector for overall device efficiency. Operation at duty cycles of 50-100% is anticipated.
An analytical formula of the emittance of and space charge effects on a sharply curved emitter surface is given. The 3D formulation makes use of the Point Charge Model (PCM) of a unit cell emitter coupled with a trajectory analysis to follow electrons to an evaluation plane where emittance is determined. The single tip theory extended to an array predicts the emittance of a Field Emitter Array 0.2...
In this work a complete design of an electron gun with a cold cathode is described. The electron gun has been designed in order to be used in THz vacuum amplifiers or oscillators. The electron gun delivers a circular electron beam with a radius of 25 μm and current of about 1.4 mA. The electron gun operates at beam voltage of 10 kV and perveance of 0,0014 μP.
Advanced particle accelerators and free electron lasers (FEL's) require high brightness electron sources. A practical figure of merit for beam "optical quality" is rms emittance, and it relates to the ability to focus the electron beam within the laser beam optical mode within the wiggler for the laser threshold to be reached.
The stable transport of high-perveance, low-voltage sheet electron beams is a key requirement for the successful development of compact, high-power sheet beam amplifiers. Here, we examine the transport of such beams in a solenoidal magnetic field and compare and contrast this transport with that produced by a periodic permanent magnet array. It is shown that a solenoid can stably transport a sheet...
The two major components, sheet beam electron gun and interaction circuit, consisting the 0.5 THz Smith-Purcell device under development are being investigated in separate diagnosis systems. The thermionic cathode showed the required emission current density of 50 A/cm2 and assembled into the electron gun. The interaction circuit fabricated by laser machining is being investigated using the precise...
Summary form only. We report results on the generation of a high-current electron beam in a diode with different type carbon fiber cathodes with and without Csl coating at a pressure of ~8x10-5 Torr, under an accelerating pulse with amplitude of ~ 300 kV and ~300 ns duration. Different diagnostics which include collimated Faraday cup array, time-resolved multi pin-hole camera, X-ray imaging of the...
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