The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
X T He - One of the best experts on this subject based on the ideXlab platform.
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effects of the imposed magnetic field on the production and transport of Relativistic Electron Beams
Physics of Plasmas, 2013Co-Authors: X T HeAbstract:The effects of the imposed uniform magnetic field, ranging from 1 MG up to 50 MG, on the production and transport of Relativistic Electron Beams (REBs) in overdense plasmas irradiated by ultraintense laser pulse are investigated with two-dimensional particle-in-cell numerical simulations. This study gives clear evidence that the imposed magnetic field is capable of effectively confining the Relativistic Electrons in space even when the source is highly divergent since it forces the Electrons moving helically. In comparison, the spontaneous magnetic fields, generated by the helically moving Electrons interplaying with the current filamentation instability, are dominant in scattering the Relativistic Electrons. As the imposed magnetic field was increased from 1 MG to 50 MG, overall coupling from laser to the Relativistic Electrons which have the potential to heat the compressed core in fast ignition was found to increase from 6.9% to 21.3% while the divergence of the REB increases significantly from 64° to ...
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generating overcritical dense Relativistic Electron Beams via self matching resonance acceleration
Physical Review Letters, 2013Co-Authors: Hongyong Wang, Libin Fu, Yingke Xu, X T HeAbstract:We show a novel self-matching resonance acceleration regime for generating dense Relativistic Electron Beams by using ultraintense circularly polarized laser pulses in near-critical density plasmas. When the self-generated quasistatic axial magnetic field is strong enough to pinch and trap thermal Relativistic Electrons, an overdense Electron bunch is formed in the center of the laser channel. In the trapping process, the Electron betatron frequencies and phases can be adjusted automatically to match the resonance condition. The matched Electrons are accelerated continuously and a collimated Electron beam with overcritical density, helical structure, and plateau profile energy spectrum is hence generated.
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density effect on Relativistic Electron Beams in a plasma fiber
Applied Physics Letters, 2010Co-Authors: C T Zhou, Xuan Wang, S Z Wu, Feng Wang, X T HeAbstract:Intense short-petawatt-laser driven Relativistic Electron Beams in a hollow high-Z plasma fiber embedded in low-Z plasmas of different densities are studied. When the plasma is of lower density than the hollow fiber, resistive filamentation of the Electron beam is observed. It is found that the Electron motion and the magnetic field are highly correlated with tens of terahertz oscillation frequency. Depending on the material property around the hollow fiber and the plasma density, the beam Electrons can be focused or defocused as it propagates in the plasma. Relativistic Electron transport and target heating are also investigated.
A. V. Arzhannikov - One of the best experts on this subject based on the ideXlab platform.
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regimes of enhanced electromagnetic emission in beam plasma interactions
Physics of Plasmas, 2015Co-Authors: I V Timofeev, V V Annenkov, A. V. ArzhannikovAbstract:The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current Relativistic Electron Beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasmaElectrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of Relativistic Electron Beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.
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Two Ways for High-Power Generation of Subterahertz Radiation by Usage of Strong Relativistic Electron Beams
IEEE Transactions on Terahertz Science and Technology, 2015Co-Authors: A. V. Arzhannikov, Manfred K. A. Thumm, A. V. Burdakov, V. S. Burmasov, N. S. Ginzburg, I. A. Ivanov, P. V. Kalinin, A. A. Kasatov, V. V. Kurkuchekov, S. A. KuznetsovAbstract:This paper describes results of studies on application of high current (1-10 kA) Relativistic Electron Beams to generate millimeter and subterahertz (sub-THz) radiation in two ways. The first one is realized at the ELMI-device where the scheme of a free Electron maser (FEM) with a sheet Electron beam is applied for the case of a planar two-beam-channel geometry. The second way is based on emission of sub-THz radiation from plasmas with turbulence induced by a strong Relativistic Electron beam. These experiments are carried out at the GOL-3 facility. We present experimental results obtained at these two devices and briefly describe their theoretical analysis.
A Marinelli - One of the best experts on this subject based on the ideXlab platform.
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coherent optical vortices from Relativistic Electron Beams
Nature Physics, 2013Co-Authors: E Hemsing, A Knyazik, M Dunning, Dao Xiang, A Marinelli, C Hast, J B RosenzweigAbstract:The interaction between light and a Relativistic Electron beam can be used to generate optical vortices in a free Electron laser, providing a way to engineer bright orbital angular momentum light at shorter X-ray wavelengths.
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nonlinear longitudinal space charge oscillations in Relativistic Electron Beams
Physical Review Letters, 2011Co-Authors: P Musumeci, Renkai Li, A MarinelliAbstract:In this Letter we study the evolution of an initial periodic modulation in the temporal profile of a Relativistic Electron beam under the effect of longitudinal space-charge forces. Linear theory predicts a periodic exchange of the modulation between the density and the energy profiles at the beam plasma frequency. For large enough initial modulations, wave breaking occurs after 1/2 period of plasma oscillation leading to the formation of short current spikes. We confirm this effect by direct measurements on a ps-modulated Electron beam from an rf photoinjector. These results are useful for the generation of intense Electron pulse trains for advanced accelerator applications.
Chiping Chen - One of the best experts on this subject based on the ideXlab platform.
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stimulated radiation from spatiotemporally gyrating Relativistic Electron Beams
Physics of Plasmas, 2000Co-Authors: J.a. Davies, Chiping ChenAbstract:A stability analysis is made of an Electron beam, propagating along and gyrating about a uniform magnetic field, for the case of a spatiotemporal equilibrium distribution in the phase angle of the transverse Electron momentum component. The axial momentum component and the magnitude of the transverse momentum component are assumed to have definite values in the equilibrium distribution. The analysis is carried out by applying Lorentz transformations to previous results for nongyrotropic equilibrium distributions. The dispersion matrix, its eigenmodes (which relate field amplitudes), and the dispersion relation are obtained. Numerical results show that varying the spatiotemporal properties of a nongyrotropic equilibrium distribution has only a small effect on maximum growth rates of radiation, but has a strong effect on the frequencies and wavenumbers at which instability occurs. A novel mechanism is found by which Electrons emit stimulated radiation at frequencies that, in principle, can be greater than t...
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Stimulated electromagnetic interactions in spatiotemporally gyrating Relativistic Electron Beams
IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297), 1999Co-Authors: J.a. Davies, Chiping ChenAbstract:Summary form only given, as follows. One possible method to significantly widen the bandwidths of present gyroklystron amplifiers is to utilize extended interaction structures in the input sections, the buncher sections and the output sections, in conjunction with stagger tuning. Through extended interactions, however, Electron Beams can undergo stimulated electromagnetic interactions, causing multimode excitations. In this paper, we investigate stimulated electromagnetic interactions in Relativistic Electron Beams gyrating in an externally applied uniform magnetic field. The Electron gyrophases are assumed to have strong spatiotemporal correlations. By applying Vlasov-Maxwell equations together with Lorentz transformations, we obtain the general dispersion relation for electromagnetic and electrostatic wave perturbations on the Electron beam for this system. The dispersion relation is used to analyze a variety of stimulated electromagnetic interactions on such Electron Beams. Results of these analyses are discussed.
J.a. Davies - One of the best experts on this subject based on the ideXlab platform.
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stimulated radiation from spatiotemporally gyrating Relativistic Electron Beams
Physics of Plasmas, 2000Co-Authors: J.a. Davies, Chiping ChenAbstract:A stability analysis is made of an Electron beam, propagating along and gyrating about a uniform magnetic field, for the case of a spatiotemporal equilibrium distribution in the phase angle of the transverse Electron momentum component. The axial momentum component and the magnitude of the transverse momentum component are assumed to have definite values in the equilibrium distribution. The analysis is carried out by applying Lorentz transformations to previous results for nongyrotropic equilibrium distributions. The dispersion matrix, its eigenmodes (which relate field amplitudes), and the dispersion relation are obtained. Numerical results show that varying the spatiotemporal properties of a nongyrotropic equilibrium distribution has only a small effect on maximum growth rates of radiation, but has a strong effect on the frequencies and wavenumbers at which instability occurs. A novel mechanism is found by which Electrons emit stimulated radiation at frequencies that, in principle, can be greater than t...
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Stimulated electromagnetic interactions in spatiotemporally gyrating Relativistic Electron Beams
IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297), 1999Co-Authors: J.a. Davies, Chiping ChenAbstract:Summary form only given, as follows. One possible method to significantly widen the bandwidths of present gyroklystron amplifiers is to utilize extended interaction structures in the input sections, the buncher sections and the output sections, in conjunction with stagger tuning. Through extended interactions, however, Electron Beams can undergo stimulated electromagnetic interactions, causing multimode excitations. In this paper, we investigate stimulated electromagnetic interactions in Relativistic Electron Beams gyrating in an externally applied uniform magnetic field. The Electron gyrophases are assumed to have strong spatiotemporal correlations. By applying Vlasov-Maxwell equations together with Lorentz transformations, we obtain the general dispersion relation for electromagnetic and electrostatic wave perturbations on the Electron beam for this system. The dispersion relation is used to analyze a variety of stimulated electromagnetic interactions on such Electron Beams. Results of these analyses are discussed.