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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...
Generation of a sheet beam directly from a scandia-doped dispenser cathode has been investigated and optimized by means of beam-profile simulations and measurements. Rectangular beams 600 mum wide and 100 mum thick with current densities over 50 A/cm2 have been generated. The beams are stable for at least several hundred hours with the cathodes operating at 950degCb, making them promising candidates...
For the generation of millimeter wave from vacuum electron devices, the microfabrication of an interaction circuit is one of the key factors. Two different technologies, a deep etch X-ray lithography (x-ray LIGA) and a deep reactive ion etching (DRIE), were employed for the comparative study and the realization of a backward-wave oscillator. Both methods showed accurate and reliable results, which...
The development of high current density sheet beam electron gun for Terahertz devices is carried-out. It operates at beam voltage of 12 kV and perveance 0.0136 mup to meet ours requirement of high beam current density 100 A/cm2 and low emittance 0.068 pi-mm-mrad at the beam-waist position. Currently, mentioned gun is being fabricated. Work has been initiated to test the performance of Scandate cathode...
An asymmetric magnet system was designed for 0.1 THz BWO devices due to the asymmetry introduced by coupling waveguide. This magnet system confines the electron beam of 12 kV and 50 mA and maintains its radius, 0.18 mm, along the circuit length.
To optimize the beam-wave interaction in a Smith-Purcell device, the characteristics such as dispersion and Q of surface mode existing on the one-dimensional array of rectangular holes were investigated. The dependence of such characteristic quantities on the structural parameters such as the width and depth of the hole was compared with the resulting beam-wave interaction.
Owing to its simple scheme and no magnet requirement, a reflex klystron is considered as a suitable device for a compact, high frequency vacuum electron device. There exists an effort to develop a terahertz reflex klystron, so-called nanoklystron.(H. Manohara et al., 2005). To increase the output power, our research group have devised a photonic crystal reflex klystron which employs a high-order-mode...
Summary form only given. Since it was first discovered, Smith-Purcell radiation (SPR) from electrons moving over a grating has been noted for its simple radiation mechanism and adopted for the generation of radiation which covers wide range of electromagnetic spectrum. These days' growing interest in Terahertz frequency regime, 0.3-3 THz, and the lack of compact tunable sources in this spectral range...
The experimental study on electron guns with high current density beam for THz devices is carried out. A thermionic electron gun is designed and the fabrication is underway. The current density requirement at the circuit is >50 A/cm2 for 0.1 THz LIGA fabricated devices [1]. A rectangular sheet electron beam for 0.5THz needs to meet the beam current density requirement of >150 A/cm2 [2].
A novel way of enhancing the Smith-Purcell radiation intensity by the use of counter-streaming electron beams and 1D slit array is introduced. The mechanism of the intensity enhancement is unveiled through numerical simulation. The experimental setup for 0.5 THz is being developed and the details of each part will be presented.
A new THz Smith-Purcell radiation (SPR) free electron laser (FEL) using counter-streaming electron beams (CSEBs) on a one-dimensionally structured metal slab is introduced. The analytical dispersion curve and the calculated SPR-intensity of the CSEBs-SPR system explain how plasmon-transmissions between the CSEBs lower the tansition-threshold from a spontaneous emission to a stimulated one as well...
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