{"title":"Three-Dimensional Simulation of Free Electron Laser with Prebunching and Efficiency Enhancement","authors":"M. Chitsazi, B. Maraghechi, M. H. Rouhani","volume":45,"journal":"International Journal of Physical and Mathematical Sciences","pagesStart":1272,"pagesEnd":1275,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/3863","abstract":"Three-dimensional simulation of harmonic up\r\ngeneration in free electron laser amplifier operating simultaneously\r\nwith a cold and relativistic electron beam is presented in steady-state\r\nregime where the slippage of the electromagnetic wave with respect\r\nto the electron beam is ignored. By using slowly varying envelope\r\napproximation and applying the source-dependent expansion to wave\r\nequations, electromagnetic fields are represented in terms of the\r\nHermit Gaussian modes which are well suited for the planar wiggler\r\nconfiguration. The electron dynamics is described by the fully threedimensional\r\nLorentz force equation in presence of the realistic planar\r\nmagnetostatic wiggler and electromagnetic fields. A set of coupled\r\nnonlinear first-order differential equations is derived and solved\r\nnumerically. The fundamental and third harmonic radiation of the\r\nbeam is considered. In addition to uniform beam, prebunched\r\nelectron beam has also been studied. For this effect of sinusoidal\r\ndistribution of entry times for the electron beam on the evolution of\r\nradiation is compared with uniform distribution. It is shown that\r\nprebunching reduces the saturation length substantially. For\r\nefficiency enhancement the wiggler is set to decrease linearly when\r\nthe radiation of the third harmonic saturates. The optimum starting\r\npoint of tapering and the slope of radiation in the amplitude of\r\nwiggler are found by successive run of the code.","references":"[1] H. P. Freund, D. Douglas, and P. G. O'Shea, \"Multiple-Beam Free-\r\nElectron Lasers,\" Nucl. Instrum. Methods A, vol. 507, pp. 373-377, July\r\n2003.\r\n[2] H. P. Freund, S. G. Biedron, S. V. Milton, \"Nonlinear Harmonic\r\nGeneration in Free-Electron Lasers,\" IEEE J. Quantum Electron, vol. 36,\r\npp. 275-280, March 2000\r\n[3] G. R. Neil, H. P. Freund, \"Nonlinear Harmonic Generation in\r\nDistributed Optical Klystrons\" Nucl. Instr. and Meth. A, vol. 475, pp.\r\n373-376. December 2001.\r\n[4] S. G. Biedron, H. P. Freund, S. V. Milton, L.-H. Yu, X. J. Wang,\r\n\"Modular Approach to Achieving the Next-Generation X-Ray Light\r\nSource,\" Nucl. Instr. and Meth. A, vol. 475, pp. 401-406, December\r\n2001.\r\n[5] M. H. Rouhani and B. Maraghechi, and H. Saberi, \" Efficiency\r\nEnhancement of a Two-Beam Free-Electron Laser,\" Phys. Plasmas, vol.\r\n16, 123105. December 2009.\r\n[6] M. H. Rouhani and B. Maraghechi, \"Efficiency Enhancement in Seeded\r\nand Self-Amplified Spontaneous Emission Free-Electron Laser,\"\r\nPhysics of plasma. vol. 16, pp. 093110, 2009.\r\n[7] H. P. Freund W. H. Miner, Jr. \"Efficiency Enhancement in Seeded and\r\nSelf-Amplified Spontaneous Emission Free-Electron Laser by Means of\r\na Tapered Wiggler,\" j. Appl. Phys. Vol. 105, pp. 113106 - 113106-6,\r\n2009.","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 45, 2010"}