نتایج جستجو برای: impact ionization

تعداد نتایج: 796390  

2017
Filip Moens Stéphanos Konstantinidis Diederik Depla

The current-time characteristic during high power pulsed magnetron sputtering is measured under identical conditions for seventeen different target materials. Based on physical processes such as gas rarefaction, ion-induced electron emission, and electron impact ionization, two test parameters were derived that significantly correlate with specific features of the current-time characteristic: (...

1999
A. L. Gutierrez-Aitken P. K. Bhattacharya

We have measured electron and hole impact ionization coefficients in biaxially strained In,Gat -&JIn,,Alll -,,As (0.44 <x <0.62,0.44 <y < 0.62) multiquantum wells for the first time. It is seen that o/a is enhanced due to strain-induced changes in band gap, band offsets, and bandstructure for tensile strain in the well and compressive strain in the barrier. The results have been interpreted by ...

2013
Siegfried SELBERHERR S. Selberherr

The topic of modern MOS-Transistor modeling is reviewed. Models for surface scattering and impact ionization, physical parameters which are of particular relevance for MOS-Transistor simulation programs, are explained. Guidelines to a mathematical analysis of the fundamental equations, which allow the judgement of numerical methods for their applicability, are presented. Examples of application...

2006
J C Berengut S D Loch C P Ballance M S Pindzola

Electron-impact ionization cross sections for the 1s2s 1 S and 1s2s 3 S metastable states of Li + are calculated using both perturbative distorted-wave and non-perturbative close-coupling methods. Term-resolved distorted-wave calculations are found to be approximately 15% above term-resolved R-matrix with pseudostates calculations. On the other hand, configuration-average time-dependent close-c...

2005
D C Griffin C P Ballance M S Pindzola F Robicheaux S D Loch J A Ludlow M C Witthoeft J Colgan C J Fontes D R Schultz

To test the validity of classical trajectory and perturbative quantal methods for electron-impact ionization of H-like ions from excited states, we have performed advanced close-coupling calculations of ionization from excited states in H, Li2+ and B4+ using the R-matrix with pseudo states and the timedependent close-coupling methods. Comparisons with our classical trajectory Monte Carlo (CTMC)...

Journal: :Physical Review A 2016

Journal: :iranian journal of science and technology (sciences) 2005
m. h. mahdieh

a three-step selective photo-ionization for gd155 and gd157 isotopes by pulsed laser wasevaluated numerically. due to large thermal neutron absorption cross sections, these two isotopes innatural gadolinium are good candidates as burnable poison to control reactivity early in the fuel cycleand allow extended fuel burn up. rate equations have been used to calculate the dynamics of the isotopepop...

2002
S. Deng F. Tsung S. Lee Wei Lu W. B. Mori T. Katsouleas P. Muggli C. OConnell E. Dodd F.-J. Decker C. Huang M. J. Hogan R. Hemker R. H. Iverson K. A. Marsh C. Ren P. Raimondi S. Wang D. Walz

Abstract. When considering intense particle or laser beams propagating in dense plasma or gas, ionization plays an important role. Impact ionization and tunnel ionization may create new plasma electrons, altering the physics of wakefield accelerators, causing blue shifts in laser spectra, creating and modifying instabilities, etc. Here we describe the addition of an impact ionization package in...

2004
M. S. Pindzola F. Robicheaux J. P. Colgan M. C. Witthoeft J. A. Ludlow

Electron-impact ionization cross sections for helium are calculated using time-dependent close-coupling theory. The total wave function for the three electron system is expanded in nine dimensions, where three dimensions are represented on a radial lattice and a coupled channels expansion is used to represent the other six dimensions. Collision cross sections are obtained by t→` projection onto...

2009
J S Marsland

Two aspects of the non-local nature of impact ionization, dead space and resonance, are investigated. The very small excess noise factor measured for mercury cadmium telluride photodiodes can only be explained if the hole to electron ionization coefficient ratio, k, is very small and the impact ionization dead space is also considered. A maximum value of k for HgCdTe is estimated in this paper....

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