Turbulent Dynamics of Beryllium Seeded Plasmas at the Edge of Tokamaks

• Published in: Contributions to plasma physics (1988) 2010-05, Vol.50 (3-5), p.374-379
• Main Authors: Shurygin, R.V., Morozov, D. Kh
• Format: Article
• Language: English
• Subjects: impurity; Tokamak; transport; turbulence
• ISSN: 0863-1042; 1521-3986
• DOI: 10.1002/ctpp.201010061

Numerical simulation of turbulent MHD dynamics of beryllium seeded plasmas at the edge of tokamaks is performed. The model is based on the 4‐fluid {∅︁, n, pe, pi } reduced nonlinear Braginsky's MHD equations. Neutral hydrogen flow from the wall is described with a diffusion model. Beryllium line radiation is taken into consideration. The Be ion distribution over ionization states is calculated using the reduced model. Electron impact ionization, three body, photo‐ and dielectronic recombination and charge‐exchange with neutral hydrogen are taken into account. Coronal equilibrium is not supposed. Simulations are performed for T‐10 parameters. Radial distributions of averaged temperatures and their fluctuation levels, species flows, impurity radiation power, and impurity ions concentrations are obtained as functions of the Be concentration at the wall. The impurity radiation is shown to act on the turbulent oscillation level significantly if the total Be concentration at the wall exceeds 3 · 1011 cm–3. The impurity turbulent transversal flow is directed inward and exceeds neoclassical flow significantly. The parallel conductivity and, as a consequence, turbulent transport are increased significantly by impurity radiation. The radiation loss dependence on the neutral Hydrogen concentration at the wall is also examined. The hydrogen concentration increasing the plasma density also rises. The relative beryllium concentration decreases. In total, these two effects are compensated, and the level of radiation losses is changed insignificantly (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)