Design of Sheet-Beam Electron Gun with Planar Cathode for Terahertz Devices

Srivastava, Anurag; So, Jin‐Kyu; Wang, Yiman; Wang, Jinshu; Raju, R. Srinivasa; Han, Sang‐Min; Park, Gun-Sik

doi:10.1007/s10762-009-9503-9

Cited by 26 publications

(5 citation statements)

References 18 publications

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“…The development of high-resolution cathode-ray tubes ͑CRTs͒ in the 1980s and 1990s required cathodes with current densities of up to 10 A / cm 2 and operation temperatures lower than that of M-type cathodes. 13 In this article, we summarize the properties of SDD cathodes and propose a new emission model based on the analysis of emission measurements and the investigation of the microstructure, surface behavior, thermochemistry, and evaporation properties. 4,5 In the 1990s pulsed laser deposition technology was studied for scandate cathode fabrication at Philips Research Laboratories ͑Ger-many͒ and BEVRI ͑China͒.…”

Section: Introductionmentioning

confidence: 99%

Emission mechanism of high current density scandia-doped dispenser cathodes

Wang¹,

Wang²,

Liu³

et al. 2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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High current, high current density field emitter array cathodes Emission uniformity enhancement between microfabricated tips in cold cathode arrays High current density field emission from arrays of carbon nanotubes and diamond-clad Si tipsThe emission mechanism of scandia-doped dispenser ͑SDD͒ cathodes is characterized based on systematic investigation of microstructure, surface behavior, evaporation, and emission. High current density SDD cathodes have been developed in recent years to meet the requirements of advanced vacuum electron devices. Space charge limited current densities of over 100 A / cm 2 have been reliably reached at a temperature of 950°C b . SDD cathodes are composed of a tungsten matrix with submicron structure and uniformly dispersed materials containing Sc, Ba, Ca, Al, and O as nanosized particulates in the matrix. The authors conclude that the copious electron emission from this cathode type results from a layer of Ba-Sc-O on W formed after activation on top of the matrix. This layer is about 100 nm thick and maintains a stable composition over its lifespan. Its emission can be explained in terms of a semiconductor layer with characteristics that differ from a metal-like emission model. The Ba-Sc-O layer is formed by codiffusion of Sc, Ba, and O ͑generated inside the W-matrix͒ to the surface of the W-matrix during activation. Furthermore, this layer guarantees a low evaporation rate of emission-relevant materials and thus enables a longer lifespan. A. Structure features of SDD cathodesUp to now, two types of SDD cathodes have been developed. They are the scandia-doped impregnated ͑SDI͒ cathodes and the scandia-doped pressed ͑SDP͒ cathodes. The SDI cathodes have a porous matrix fabricated by calcining, a͒ Electronic Wang et al.: Emission mechanism of high current density scandia-doped dispenser cathodes 04E106-2 04E106-2 Wang et al.: Emission mechanism of high current density scandia-doped dispenser cathodes 04E106-7 04E106-7 JVST B -Microelectronics and Nanometer Structures Redistribution subject to AVS license or copyright; see http://scitation.aip.org/termsconditions. Download to IP: 84.88.136.149 On: Tue, 02 Dec 2014 08:38:57 Wang et al.: Emission mechanism of high current density scandia-doped dispenser cathodes 04E106-8 04E106-8

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Section: Introductionmentioning

confidence: 99%

Emission mechanism of high current density scandia-doped dispenser cathodes

Wang¹,

Wang²,

Liu³

et al. 2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…The charge quantity of the bunch is 1 pC and the initial electron-energy is 100 keV. To avoid the dispersion of particles within the bunch caused by the space-charge effect, a static uniform longitudinal magnetic field B z = 0.4 T is used to transversely confine the FEB [33][34][35]. The distance between the beam and the model surface is 0.1 mm.…”

Section: Theoretical Analyses and Simulationsmentioning

confidence: 99%

Enhanced Smith–Purcell radiation by coupling surface plasmons on meta-films array with resonator modes on a grating

Liu¹,

Liu²,

Jia³

et al. 2018

J. Phys. D: Appl. Phys.

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We propose to use uniformly moving free-electrons to excite an array of alternatedly lined metamaterial thin-films (meta-films) and open-resonators. The surface plasmon polaritons on meta-films and the resonant modes within open-resonators are both excited, and are coupled to each other in the open-resonators. This coupling remarkably increases the intensities of resonant modes, which then generate enhanced coherent Smith-Purcell radiation (SPR). Compared with conventional SPRs, the present scheme combines the advantages of both material and structure profile, and its radiation power is more than an order of magnitude higher. Thus it offers a promising way for developing efficient terahertz sources.

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“…Consequently, the research on sheet-beam TWTs has emerged as a prominent area of focus in the field of vacuum electronics [14][15][16][17][18]. Extensive research has been conducted on the design and implementation of electron gun specifically tailored for THz TWTs [19][20][21][22][23][24]. The successful development of THz TWTs with the desired gain, efficiency, and operational stability greatly depends on the fabrication of tiny gun parts and their assembly with utmost precision.…”

Section: Introductionmentioning

confidence: 99%

Design and development of a sheet-beam electron gun with large current for a THz traveling-wave tube

Chen,

Xu,

Sun

et al. 2023

AJP

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In this paper, the design, development and experimental investigation on a sheet-beam electron gun with large current for a THz traveling-wave tube (TWT), which can operate typically at 0.22 THz frequency, is reported. The cylindrical cathode is made of scandate, and the pencil electron beam is compressed into a sheet beam by an elliptical focusing electrode. The maximum beam current of 123.4 mA was predicted with the emission current density of 24.56 A/cm 2 in simulation with 22 kV beam voltage. In the sheet-beam electron gun, the distance between the emission surface of the cathode and the beam-waist was found as 11 mm, and the wide edge and narrow edge of the beam waist crosssection are 0.38 mm and 0.1 mm, respectively. The components of the sheet-beam electron gun were fabricated and subsequently assembled. Its assembly errors were detected. The simulation predicts that the beam transportation in the sheet-beam electron gun under the condition of assembly errors exceeds 96%. The study also includes the experimental characterization of the cathode emission of the gun. The preliminary experimental results of the sheet-beam electron gun indicate that the beam current of 80 mA with the beam voltage of 22 kV was obtained from the proposed design. The experiment remained useful towards development of a 0.22 THz futuristic TWT.

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Design of Sheet-Beam Electron Gun with Planar Cathode for Terahertz Devices

Cited by 26 publications

References 18 publications

Emission mechanism of high current density scandia-doped dispenser cathodes

Emission mechanism of high current density scandia-doped dispenser cathodes

Enhanced Smith–Purcell radiation by coupling surface plasmons on meta-films array with resonator modes on a grating

Design and development of a sheet-beam electron gun with large current for a THz traveling-wave tube

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