Free-boundary simulations with the XTOR-2F code. (10th May 2017)

• Record Type: Journal Article
• Authors: Marx, A; Lütjens, H
• Is Part Of: Plasma physics and controlled fusion. Volume 59:Number 6(2017:Jun.)
• Publication Date: 2017-05-10
• Subjects: free-boundary -- resistive wall -- magnetohydrodynamics -- nonlinear simulations -- tokamak -- plasma; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/1361-6587/aa6d1f
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: The XTOR-2F code simulates the 3D dynamics of full bi-fluid MHD instabilities in tokamak plasmas (Lütjens and Luciani 2010 J. Comput. Phys. 229 8130). The original fixed boundary computational domain of the code was generalized to a free-boundary one, thus approaching closely the geometry of today's and future large experimental devices. The initial conditions for XTOR-2F are given by the CHEASE equilibrium code (Lütjens et al O 1996 Comput. Phys. Commun. 97 219) inside the plasma. Outside the plasma, the solution is extended by fitting the magnetic potential at the CHEASE computation domain boundary with a set of external poloidal magnetic coils. The boundary conditions use Green functions to construct a response matrix matching the normal and tangential components of the outside magnetic field with the inside solution. A thin resistive wall can be added to the computational domain. This new numerical setup generalizes the XTOR-2F investigation field from internal MHD instabilities such as internal kinks and tearings towards external instabilities. The code linear behavior is validated with two families of instabilities, n = 0 axisymmetric modes and n = 1 / m = 2 external kinks. In order to validate the nonlinear behavior with these magnetic structure modifications, nonlinear resistive MHD simulations of tearing modes at zero beta evolving to a stationary state have been performed.