The Experts below are selected from a list of 60246 Experts worldwide ranked by ideXlab platform
Dmytro M Vavriv - One of the best experts on this subject based on the ideXlab platform.
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advances in spatial harmonic magnetrons with cold Secondary Emission cathode
European Microwave Conference, 2017Co-Authors: Dmytro M Vavriv, Vasyliy D Naumenko, Klaus Schuenemann, Vladymyr A Markov, Aleksandr N SyvorovAbstract:The spatial-harmonic magnetron with cold Secondary-Emission cathode is an effective source of radiation up to 210 GHz frequency range. State of the art in the design, realization, and investigation of such magnetrons is described. Examples of the successful developments of low-voltage tubes, tubes with a long output pulse duration, and Sub-THz magnetrons are presented in more detail.
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toward terahertz magnetrons 210 ghz spatial harmonic magnetron with cold cathode
IEEE Transactions on Electron Devices, 2012Co-Authors: N I Avtomonov, K Schunemann, Dmytro M Vavriv, Vasyliy D Naumenko, A N Suvorov, Vladymyr A MarkovAbstract:The development of a 210-GHz spatial-harmonic magnetron with a cold Secondary-Emission cathode is presented. The development includes a detailed self-consistent tube simulation and optimization. Based on these results, 210-GHz tubes providing over 1-kW peak power were produced and tested. Experimental results are consistent with the simulation.
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self consistent simulation of the spatial harmonic magnetron with cold Secondary Emission cathode
IEEE Transactions on Electron Devices, 2001Co-Authors: K Schunemann, S V Sosnytskiy, Dmytro M VavrivAbstract:A self-consistent mathematical model of the spatial-harmonic magnetron (SHM), with cold Secondary-Emission cathode is proposed for investigating steady-state processes. Characteristic features of modeling space charge effects, Secondary Emission, and nonlinear electron-wave interaction are described. Illustrative examples of simulations are given in order to show peculiarities of the operation of the SHM as compared to conventional magnetrons. Multi-stable states of the magnetron are described. Results of simulations are compared with experimental data for an 8-mm-wave magnetron.
K Schunemann - One of the best experts on this subject based on the ideXlab platform.
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particle in cell simulation of a spatial harmonic magnetron with a cold Secondary Emission cathode
IEEE Transactions on Plasma Science, 2012Co-Authors: Nasr N Esfahani, K SchunemannAbstract:A 16-vane millimeter-wave spatial-harmonic magnetron (SHM) with a cold Secondary Emission cathode is examined by the use of a 3-D particle-in-cell (PIC) code embedded in CST Particle Studio. Simulations of the SHM are performed without artificial RF priming and without assuming restrictive assumptions on the mode of operation or on the number of harmonics to be considered. Thus, in our simulations, the electromagnetic oscillations grow naturally from noise. Time-evolved space-charge simulations and gradual formation of a single-frequency RF oscillation are presented. Examination of space-charge profiles at saturation time reveals the presence of two different space-charge distributions that depend on the amount of primary Emission current. This current is employed to model a bombarding current, which is used to initialize the cold cathode. It is shown that a small primary Emission density results in nonperiodic distribution of space charge at saturation time, which is in accordance with the previously reported space-charge distribution in SHMs. The simulated current, power, and efficiency indicate good correlation with the experimental results.
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toward terahertz magnetrons 210 ghz spatial harmonic magnetron with cold cathode
IEEE Transactions on Electron Devices, 2012Co-Authors: N I Avtomonov, K Schunemann, Dmytro M Vavriv, Vasyliy D Naumenko, A N Suvorov, Vladymyr A MarkovAbstract:The development of a 210-GHz spatial-harmonic magnetron with a cold Secondary-Emission cathode is presented. The development includes a detailed self-consistent tube simulation and optimization. Based on these results, 210-GHz tubes providing over 1-kW peak power were produced and tested. Experimental results are consistent with the simulation.
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self consistent simulation of the spatial harmonic magnetron with cold Secondary Emission cathode
IEEE Transactions on Electron Devices, 2001Co-Authors: K Schunemann, S V Sosnytskiy, Dmytro M VavrivAbstract:A self-consistent mathematical model of the spatial-harmonic magnetron (SHM), with cold Secondary-Emission cathode is proposed for investigating steady-state processes. Characteristic features of modeling space charge effects, Secondary Emission, and nonlinear electron-wave interaction are described. Illustrative examples of simulations are given in order to show peculiarities of the operation of the SHM as compared to conventional magnetrons. Multi-stable states of the magnetron are described. Results of simulations are compared with experimental data for an 8-mm-wave magnetron.
D M Parkes - One of the best experts on this subject based on the ideXlab platform.
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crossed field Secondary Emission electron source
Physics of Plasmas, 1997Co-Authors: Y M Saveliev, W Sibbett, D M ParkesAbstract:A novel crossed-field Secondary-Emission (CFSE) electron source that is capable of producing high-current tubular electron beams is described. This new electron source is based on the mechanism of Secondary-Emission multiplication of electron current in a magnetron-like device having smooth cylindrical electrodes. The input electron current may be as low as a few mA. The multiplication process starts at the negative slope of an applied voltage pulse. After initiation, the current is extracted from the diode region with no regard to the voltage pulse shape and as a consequence, the CFSE electron source can operate in a long pulse mode. At the diode voltage of ∼40 kV for a diode gap of ∼6 mm, the output current reaches a value of more than 100 A.
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crossed field Secondary Emission electron source
IEEE International Pulsed Power Conference, 1997Co-Authors: Y M Saveliev, W Sibbett, D M ParkesAbstract:A novel crossed-field Secondary-Emission (CFSE) electron source that is capable of producing high current tubular electron beams is described. This new electron source is based on the mechanism of Secondary Emission multiplication of electron current in a magnetron-like device having smooth cylindrical electrodes. The input electron current may be as low as a few mA. The multiplication process starts at the negative slope of an applied voltage pulse. After initiation, the current is extracted from the diode region with no regard to the voltage pulse shape and as a consequence, the CFSE electron source can operate in a long pulse mode. At the diode voltage of /spl sim/40 kV for a diode gap of /spl sim/6 mm, the output current reaches a value of more than 100A. A further increase of current up to 1 kA is feasible.
M. Rosenberg - One of the best experts on this subject based on the ideXlab platform.
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role of grain size and particle velocity distribution in Secondary electron Emission in space plasmas
Journal of Geophysical Research, 1993Co-Authors: V W Chow, D. A. Mendis, M. RosenbergAbstract:By virtue of being generally immersed in a plasma environment, cosmic dust is necessarily electrically charged. The fact that Secondary Emission plays an important role in determining the equilibrium grain potential has long been recognized, but the fact that the grain size plays a crucial role in this equilibrium potential, when Secondary Emission is important, has not been widely appreciated. Using both conducting and insulating spherical grains of various sizes and also both Maxwellian and generalized Lorentzian plasmas (which are believed to represent certain space plasmas), we have made a detailed study of this problem. In general, we find that the Secondary Emission yield δ increases with decreasing size and becomes very large for grains whose dimensions are comparable to the primary electron penetration depth, such as in the case of the very small grains observed at comet Halley and inferred in the interstellar medium. Moreover, we observe that δ is larger for insulators and equilibrium potentials are generally more positive when the plasma has a broad non-Maxwellian tail. Interestingly, we find that for thermal energies that are expected in several cosmic regions, grains of different sizes can have opposite charge, the smaller ones being positive while the larger ones are negative. This may have important consequences for grain accretion in polydisperse dusty space plasmas.
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role of grain size and particle velocity distribution in Secondary electron Emission in space plasmas
Journal of Geophysical Research, 1993Co-Authors: V W Chow, D. A. Mendis, M. RosenbergAbstract:By virtue of being generally immersed in a plasma environment, cosmic dust is necessarily electrically charged. The fact that Secondary Emission plays an important role in determining the equilibrium grain potential has long been recognized, but the fact that the grain size plays a crucial role in this equilibrium potential, when Secondary Emission is important, has not been widely appreciated. Using both conducting and insulating spherical grains of various sizes and also both Maxwellian and generalized Lorentzian plasmas (which are believed to represent certain space plasmas), we have made a detailed study of this problem. In general, we find that the Secondary Emission yield delta increases with decreasing size and becomes very large for grains whose dimensions are comparable to the primary electron penetration depth, such as in the case of the very small grains observed at comet Halley and inferred in the interstellar medium. Moreover, we observed that delta is larger for insulators and equilibrium potentials are generally more positive when the plasma has a broad non-Maxwellian tail. Interestingly, we find that for thermal energies that are expected in several cosmic regions, grains of different sizes can have opposite charge, the smaller ones being positive while the larger ones are negative. This may have important consequences for grain accretion in polydisperse dusty space plasmas.
J M Paredes - One of the best experts on this subject based on the ideXlab platform.
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leptonic Secondary Emission in a hadronic microquasar model
Astronomy and Astrophysics, 2007Co-Authors: Mariana Orellana, P Bordas, V Boschramon, Gustavo E Romero, J M ParedesAbstract:Fil: Orellana, Mariana Dominga. Provincia de Buenos Aires. Gobernacion. Comision de Investigaciones Cientificas. Instituto Argentino de Radioastronomia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Instituto Argentino de Radioastronomia; Argentina
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leptonic Secondary Emission in a hadronic microquasar model
arXiv: Astrophysics, 2007Co-Authors: Mariana Orellana, P Bordas, V Boschramon, Gustavo E Romero, J M ParedesAbstract:Context: It has been proposed that the origin of the very high-energy photons emitted from high-mass X-ray binaries with jet-like features, so-called microquasars (MQs), is related to hadronic interactions between relativistic protons in the jet and cold protons of the stellar wind. Leptonic Secondary Emission should be calculated in a complete hadronic model that include the effects of pairs from charged pion decays inside the jets and the Emission from pairs generated by gamma-ray absorption in the photosphere of the system. Aims: We aim at predicting the broadband spectrum from a general hadronic microquasar model, taking into account the Emission from secondaries created by charged pion decay inside the jet. Methods: The particle energy distribution for Secondary leptons injected along the jets is consistently derived taking the energy losses into account. We also compute the spectral energy distribution resulting from these leptons is calculated after assuming different values of the magnetic field inside the jets. The spectrum of the gamma-rays produced by neutral pion-decay and processed by electromagnetic cascades under the stellar photon field. Results: We show that the Secondary Emission can dominate the spectral energy distribution at low energies (~1 MeV). At high energies, the production spectrum can be significantly distorted by the effect of electromagnetic cascades. These effects are phase-dependent, and some variability modulated by the orbital period is predicted.
