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The Atomic K- and L-shell Ionization Cross-sections by Electron Impact

  • Changhuan Tang
  • Zhengming Luo
  • Zhu An
  • Fuqing He
  • Xiufeng Peng
  • Xianguan Long

Abstract

The experimental and theoretical study of atomic inner-shell ionization cross- sections by electron impact, a subject of scientific study for many years, is important both for understanding the interaction between electrons and atoms and for technology application1. The cross-section for the ionization of atoms and molecules by electron impact is one of the essential sets of data needed in a wide range of applications. For example, this can be used to the impurity diagnosis of magnetic fusion devices. It is well known that radiative cooling by low- and high-Z impurities accounts for a significant fraction of the power loss from tokamak plasmas. Several investigations have shown that the impurity radiation can seriously impair tokamak performance. The study of soft x-rays emitted between 1–20keV has, therefore, increased in importance, furnishing electron temperature data and a wealth of impurity information. In general, the power radiated by an impurity ion, i in a charged state, j can be expressed as2
$$ P(T_e )_{ij} = n_e n_i (\frac{{n_{ij} }} {{n_i }})\langle \sigma v(T_e )\rangle _{ij} EkeV/(cm^3 \cdot s) $$
(1)
where ne and ni denote the electron density and the total density of the ith impurity element, respectively. The density ratio nij/ni is the relative abundance of the jth ionic charge state of the impurity i. E is the x-ray energy emitted by impurity, and <σ v (Te)> refers to the total excitation cross-section averaged over a Maxwellian velocity distribution. From Eq. (1), we can see that the atomic inner-shell ionization cross-sections are essential parameters in calculation of the power loss in the tokamak.

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Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Changhuan Tang
    • 1
  • Zhengming Luo
    • 2
  • Zhu An
    • 2
  • Fuqing He
    • 2
  • Xiufeng Peng
    • 2
  • Xianguan Long
    • 2
  1. 1.National Key Laboratory of Laser FusionResearch Center of Laser Fusion, CAEPMianyang, SichuanP. R. China
  2. 2.Key Laboratory for Radiation Physics and Technology of Education Ministry of China, Institute of Nuclear Science and TechnologySichuan UniversityChengduP. R. China

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