Electron impact excitation of helium in Debye plasma

Abstract

The probability, differential, and integral scattering cross sections of the 11S→21S and 11S→21P transitions of helium have been calculated in the first Born approximation. The projectile-target interactions depending on the temperature and the density of plasma are described by the Debye-Hückel model. Wave functions of the target before and after collision were modeled by non orthogonal Hartree-Fock orbitals. The wave functions parameters are calculated with the Ritz variational method. We improve our unscreened first Born approximation integral cross sections by using the BE-scaled (B stands for binding energy and E excitation energy) method. The second Born approximation has also been used to calculate the excitation cross sections in Debye plasma. Our calculations are compared to other theoretical and experimental results where applicable.

Flow shear suppression of pedestal ion temperature gradient turbulence-A first principles theoretical framework

“…We note that this ITG turbulence is not the dominant pedestal transport mechanism in most present day experiments precisely due to its suppression by shear flow. The most important fluctuations are likely electron temperature gradient turbulence [29][30][31][32][33], microtearing modes [17,33], and low-n (toroidal mode number) magnetic fluctuations [34][35][36][37][38]-all of which are expected to be much less sensitive to shear flow than ITG.…”