Emission cross sections for neutral xenon impacted by Xe+ and Xe2+

Ion impact emission cross sections for eleven transitions from the 5p56p configuration to the 5p56s configuration of neutral xenon occurring in the spectral region between 700 nm and 1000 nm have been measured experimentally. Collisions between both singly- and doublyionized xenon and neutral xenon have been studied. These cross sections are of primary use in the development of a spectrographic diagnostic for Hall effect thruster plasma. A detailed discussion of the experimental methods and the subsequent data reduction is included. The results are presented and the importance of these data for spectrographic emission models of Hall effect thruster plasmas is discussed.

Application of the Boundary Method to the determination of the properties of the beam cross-sections

Using the 3-D equations of linear elasticity and the asylllptotic expansion methods in terms of powers of the beam cross-section area as small parameter different beam theories can be obtained, according to the last term kept in the expansion. If it is used only the first two terms of the asymptotic expansion the classical beam theories can be recovered without resort to any "a priori" additional hypotheses. Moreover, some small corrections and extensions of the classical beam theories can be found and also there exists the possibility to use the asymptotic general beam theory as a basis procedure for a straightforward derivation of the stiffness matrix and the equivalent nodal forces of the beam. In order to obtain the above results a set of functions and constants only dependent on the cross-section of the beam it has to be computed them as solutions of different 2-D laplacian boundary value problems over the beam cross section domain. In this paper two main numerical procedures to solve these boundary value pf'oblems have been discussed, namely the Boundary Element Method (BEM) and the Finite Element Method (FEM). Results for some regular and geometrically simple cross-sections are presented and compared with ones computed analytically. Extensions to other arbitrary cross-sections are illustrated.