Data for Beryllium–Hydrogen Charge Exchange in One and Two Centres Models, Relevant for Tokamak Plasmas

Abstract

Data on the cross section and kinetic rate of charge exchange (CX) between the bare beryllium nucleus, the ion Be(+4) and the neutral hydrogen atom are of great interest for visible-range high-resolution spectroscopy in the ITER tokamak because beryllium is intended as the material for the first wall in the main chamber. Here an analysis of available data is presented, and the data needs are formulated. Besides the active probe signal produced by the CX of the diagnostic hydrogen neutral beam with impurity ions in plasma, a passive signal produced by the CX of impurity ions with cold edge plasma is also important, as it shows in observation data from the JET (Joint European Torus) tokamak with an ITER-like beryllium wall. Data in the range of a few eV/amu to ~100 eV/amu (amu stands for the atomic mass unit) needed for simulations of level populations for principal and orbital quantum numbers in the emitting beryllium ions Be(+3) can be obtained with the help of two-dimensional kinetic codes. The lack of literature data, especially for data resolved in orbital quantum numbers, has instigated us to make numerical calculations with the ARSENY code. A comparison of the results obtained for the one-centre Coulomb problem using an analytic approach and for the two-centre problem using numerical simulations is presented.

On the Effects of Tokamak Plasma Edge Symmetries on Turbulence Relaxation

“…We now discuss to which extent the present model is, in practice, relevant for describing the edge plasma physics of a tokamak machine. First of all, we observe that the two-fluid description adopted above is appropriate to describe the edge plasma dynamics because, immediately out of the separatrix, the lower temperature makes the mean free path of ions and electrons much smaller than the magnetic connection length [15,17,18]. Therefore, the collisionality increases enough with respect to the core of a tokamak plasma that a fluid model is viable, and the kinetic and gyrokinetic effects remain small for as far as we are considering turbulence phenomena (for which the time scale is much longer than the inverse of the ion gyrofrequency).…”

Special Issue Editorial “Atomic Processes in Plasmas and Gases: Symmetries and Beyond”

“…P.A. Sdvizhenskii et al, in the paper "Data for Beryllium-Hydrogen Charge Exchange in One and Two Centres Models, Relevant for Tokamak Plasmas" [3], presented the analysis of data on the cross section and kinetic rate of charge exchange (CX) between the bare beryllium nucleus, the ion Be(+4), and the neutral hydrogen atom. These data are of great interest for visible-range high-resolution spectroscopy in the ITER tokamak because beryllium is intended as the material for the first wall in the main chamber.…”