Extended MHD modeling
Effects of Finite Larmor Radius on Equilibria with Flow in Reduced TwoFluid
ModelsFor steep plasma profiles in improved confinement modes of magnetically confined plasmas, smallscale effects not included in the ideal magnetohydrodynamic (MHD) model could be significant. Our goal is to model actual equilibria in more detail by extending the MHD model to include the smallscale effects relevant to fusion plasmas.
Figures (a) ? (c) show the numerical solutions of the equations for flowing equilibria with effects of twofluid and ion finite radius: (a) magnetic flux surfaces, (b) pressure isosurfaces and (c) isosurfaces of the ion stream function at a poloidal crosssection of the torus. Flows in plasmas may play important roles for sustaining steep profiles. The results show the flow causes the departure of pressure isosurfaces from the magnetic flux surfaces and the isosurfaces of the ion stream funcion do not coincide with the magnetic flux surfaces due to the small scale effects. These complex equilibrium structures different from the standard MHD static equilibria have been given by the derivation of the equilibrium equations by asymptotic expansions and the numerical analysis with a finite element method.
Reference
A. Ito and N. Nakajima, AIP Conference Proceedings Vol. 1069, pp.121 (2008).
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