High Emittance Electron Beam Source Coupled to Slab Loaded Accelerating Structure
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High Emittance Electron Beam Source Coupled to Slab Loaded Accelerating Structure J. Zafar & H. Zafar & K. Masood & A. A. P. Gibson
Received: 23 June 2008 / Accepted: 3 September 2008 / Published online: 13 September 2008 # Springer Science + Business Media, LLC 2008
Abstract High power line source emitter assembly was coupled to a twin symmetric Hplane slab loaded accelerating structure for beam acceleration. Closed form field analysis of the accelerating structure that includes guideline information regarding modal hierarchy, mode nomenclature, propagation plane, cut-off plane and dispersion relations is presented. Furthermore it was confirmed that by using symmetrically loaded dielectric accelerating structures with one rotated through 90° results in exerting a uniform acceleration impact on a travelling beam passing through the structure. Keywords Electron gun . Beam power . Accelerating structure . Focusing electrodes . Cut-off plane
1 Introduction Due to the growing interest, thermionic electron guns continue to be of importance in multifarious industrial and metallurgical processes for heating, coating, refining, melting, and welding applications [1–3]. The governing physical and electro-optical laws in electron beam processing techniques regarding electron emission, beam generation and beam guidance are practically the same [4–6]. However optimized electron beam parameters and performance characteristics which includes beam power, acceleration voltage, emission current, perveance, working pressure, beam spot size and emittance are pre-requisite for a peculiar design consideration. There are many different configurations for thermionic H. Zafar Microwave Research Group, University of South Asia, Lahore 54000, Pakistan K. Masood Department of Physics, INMOL, Lahore 54600, Pakistan J. Zafar (*) : A. A. P. Gibson Microwave and Communication Systems Research Group, School of Electrical & Electronic Engineering, University of Manchester, Manchester M60 1QD England, UK e-mail: [email protected]
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Int J Infrared Milli Waves (2008) 29:1205–1214
electron guns including: axial electron guns [7, 8], transverse electron guns [9, 10], ring guns [11, 12], linear guns [13, 14] and bent-beam guns [15]. In section II we will briefly describe some generic features of a magnetically confined line source emitter assembly. The complete and detailed design of this emitter assembly has been described elsewhere [27]. Emission characteristics that include emission current dependence upon the cathode heating power and acceleration voltage and other performance characteristics of this emitter line source were also mentioned therein [27]. This emitter assembly is coupled to a dielectric slab loaded accelerating structure for the purpose of beam acceleration. Renewed interest has been attributed to such slab loaded waveguide accelerating structures, [16–18, 20, 24] due to their ability to generate high acceleration gradient [19] and focused beams [20–24]. Closed form field analysis of the accelerating struct
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