A general expression for the excitation cross section of polarized atoms by polarized elect.pdf
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A general expression for the excitation cross section
of polarized atoms by polarized electrons
A Kupliauskiene?
Institute of Theoretical Physics and Astronomy of Vilnius University, A.Gos?tauto 12,
01108 Vilnius, Lithuania
E-mail: akupl@itpa.lt
Abstract. The general expression for excitation cross section of polarized atoms by
polarized electrons is derived by using the methods of the theory of an atom adapted
for polarization. The special cases of the general expression for the description of the
angular distribution and alignment of excited atoms in the case of polarized and non-
polarized atoms as well as the magnetic dichroism of the total ionization cross section
of polarized atoms are obtained. The cross sections and alignment parameters for the
excitation of the autoionizing states 2p53s2 2P3/2 for Na and 3p
54s2 2P3/2 for K are
calculated in distorted wave with exchange approximation.
PACS numbers: 34.80.Df, 31.50.df, 29.25.Pj
Excitation cross section of polarized atoms by polarized electrons 2
1. Introduction
Polarized atoms and ions presents in plasma where directed flows of charged particles
take place. The directed movement of these particles is very important in laboratory and
astrophysical plasmas resulting in the distortion of Maxwellian distribution of electrons
[1]. The non-equilibrium population of magnetic sub-levels or the ordering of angular
momentum of atomic particles that is called a self-alignment is causes the polarization
of the emitted electromagnetic fluorescence radiation that could be used for the fusion
plasma diagnostics [2]. Recently, the methods of the theory of an atom were applied for
the derivation of the general expressions describing the interaction of polarized photons
and electrons with polarized atoms and ions [3-9]. The probability (cross section) of the
interaction was expressed as multiple expansion over the multipol
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