scholarly journals Theoretische Untersuchungen an einem Elektronenstrahlerzeuger mit Spitzenkathode / Theoretical Investigation of an Electron Gun with a Point Cathode

1978 ◽  
Vol 33 (8) ◽  
pp. 910-913 ◽  
Author(s):  
H. Rauh ◽  
D. Kern
Keyword(s):  
Initial Conditions ◽  
Current Density Distribution ◽  
Expansion Method ◽  
Beam Current ◽  
Electron Gun ◽  
Beam Current Density ◽  
Electron Trajectories ◽  
Imaging Theory ◽  
Fifth Order ◽  
Series Expansion Method

Electron-optical properties of a gun with a point cathode are determined numerically by tracing a greater number of electron trajectories. In order to calculate the beam current density distribution, an attempt was made to describe the properties of the gun in terms of the parameters describing the initial conditions of the trajectories. Contrary to the conventional electron-optical imaging theory, the electron gun under consideration cannot be sufficiently characterized by a few aberration coefficients, since only a small fraction of the trajectories forming the electron beam would be covered by an expansion containing linear, third and fifth order terms, so that the series expansion method is not applicable.

scholarly journals NUMERICAL ANALYSIS OF LASING DYNAMICS IN VOLUME FREE ELECTRON LASER

2008 ◽  
Vol 13 (2) ◽  
pp. 263-273
Author(s):  
Svetlana Sytova
Keyword(s):  
Electron Beam ◽  
Free Electron ◽  
Free Electron Laser ◽  
Initial Conditions ◽  
Beam Current ◽  
Beam Current Density ◽  
Electron Beam Current ◽  
Nonlinear Phenomena ◽  
Experimental Development ◽  
Lasing Dynamics

Nonlinear phenomena originating in volume free electron laser (VFEL) are investigated by methods of mathematical modelling using computer code VOLC. It was demonstrated the possibility of excitation of quasiperiodic oscillations not far from threshold values of electron beam current density and VFEL resonator length. It was investigated sensibility of numerical solution to initial conditions for different VFEL regimes of operation. Parametric maps with respect to electron beam current and detuning from synchronism condition present complicated root to chaos with windows of periodicity in VFEL. Investigation of chaotic lasing dynamics in VFEL is important in the light of experimental development of VFEL in Research Institute for Nuclear Problems.

scholarly journals Fore-vacuum plasma-cathode electron sources

2008 ◽  
Vol 26 (4) ◽  
pp. 619-635 ◽  
Author(s):  
V.A. Burdovitsin ◽  
E.M. Oks
Keyword(s):  
Electron Beam ◽  
High Pressures ◽  
Electrical Breakdown ◽  
Current Density Distribution ◽  
Beam Current ◽  
Beam Current Density ◽  
Beam Power ◽  
Plasma Cathode ◽  
Local Maxima ◽  
Electron Sources

AbstractThis paper presents a review of physical principles, design, and performances of plasma-cathode direct current (dc) electron beam guns operated in so called fore-vacuum pressure (1–15 Pa). That operation pressure range was not reached before for any kind of electron sources. A number of unique parameters of the e-beam were obtained, such as electron energy (up to 25 kV), dc beam current (up 0.5 A), and total beam power (up to 7 kW). For electron beam generation at these relatively high pressures, the following special features are important: high probability of electrical breakdown within the accelerating gap, a strong influence of back-streaming ions on both the emission electrode and the emitting plasma, generation of secondary plasma in the beam propagation region, and intense beam-plasma interactions that lead in turn to broadening of the beam energy spectrum and beam defocusing. Yet other unique peculiarities can occur for the case of ribbon electron beams, having to do with local maxima in the lateral beam current density distribution. The construction details of several plasma-cathode electron sources and some specific applications are also presented.

Beam current density distribution of a vacuum arc ion source

1998 ◽  
Vol 69 (2) ◽  
pp. 807-809 ◽  
Author(s):  
A. G. Nikolaev ◽  
E. M. Oks ◽  
Xiaoji Zhang ◽  
Cheng Cheng
Keyword(s):  
Density Distribution ◽  
Current Density ◽  
Current Density Distribution ◽  
Beam Current ◽  
Ion Source ◽  
Vacuum Arc ◽  
Beam Current Density

HOLE–SPIN COUPLING AND SPIN DISTORTION IN HIGH Tc SUPERCONDUCTORS

1995 ◽  
Vol 09 (24) ◽  
pp. 1589-1594
Author(s):  
M. TIWARI ◽  
R. A. SINGH
Keyword(s):  
Correlation Function ◽  
Green Function ◽  
Low Temperature ◽  
Function Theory ◽  
Expansion Method ◽  
Temperature Series ◽  
Spin Coupling ◽  
High Tc Superconductors ◽  
High Tc ◽  
Series Expansion Method

The effect of hole–spin coupling together with spin distortion on the energy and hole correlation function have been studied in detail. Standard Green function theory and Low Temperature Series Expansion method have been utilised to get analytical results.

scholarly journals Approximation of the Orientation Distribution of Grains in Polycrystalline Samples by Means of Gaussians

1992 ◽  
Vol 19 (1-2) ◽  
pp. 9-27 ◽  
Author(s):  
D. I. Nikolayev ◽  
T. I. Savyolova ◽  
K. Feldmann
Keyword(s):  
Rolling Texture ◽  
Expansion Method ◽  
Operating Mode ◽  
Orientation Distribution ◽  
New Method ◽  
Gaussian Distributions ◽  
Positivity Condition ◽  
The Central Limit Theorem ◽  
Pole Figures ◽  
Series Expansion Method

The orientation distribution function (ODF) obtained by classical spherical harmonics analysis may be falsified by ghost influences as well as series truncation effects. The ghosts are a consequence of the inversion symmetry of experimental pole figures which leads to the loss of information on the “odd” part of ODF.In the present paper a new method for ODF reproduction is proposed. It is based on the superposition of Gaussian distributions satisfying the central limit theorem in the SO(3)-space as well as the ODF positivity condition. The kind of ODF determination offered here is restricted to the fit of Gaussian parameters and weights with respect to the experimental pole figures. The operating mode of the new method is demonstrated for a rolling texture of copper. The results are compared with the corresponding ones obtained by the series expansion method.

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