Set of wires to simulate tokamaks with poloidal divertor

Abstract

Simple wire models have been proposed to simulate magnetic configurations in tokamaks. Here we consider electric currents in five parallel infinite wires to obtain double-null magnetic surfaces with specific choices of magnetic axis positions, triangularity, and elongation. As an example, we choose the position and the electric current of each wire to obtain magnetic surfaces similar to those expected in the tokamak international thermonuclear experimental reactor. Moreover, we also integrate the perturbed field line differential equation to simulate chaotic layers near the hyperbolic points and deposition patterns at the divertor plate observed in tokamaks. To simulate that, we add to the model a perturbing error field, due to asymmetries in the tokamak coils, and introduce a random collisional term to the field line mapping to reproduce escape pattern alterations due to particle collisions.

Magnetohydrodynamic Description of the Equilibrium and Heating of the Thermal Plasma

“…Sometimes these constructions are called "wire models" since the coils added mathematical are equivalent to toroidal current-carrying wires at the positions R j , Z j . Examples of these equilibrium are given in Kroetz, et al (2013) and Abdullaev, et al (2006). The single-null divertor is studied in detail with choices of the triangularity and elongation and position of the X-point with respect to magnetic axis of the plasma for modeling JET, ASDEX and ITER.…”

Delineating the magnetic field line escape pattern and stickiness in a poloidally diverted tokamak

“…We will consider in this work a simple model that consists of five wire loops carrying electric currents, with the same relative position proposed in [9], as following, Each magnetic surface has a well-defined characteristic known as rotation number, which is the average of the poloidal angle performed by a field line after a full toroidal turn. In this model, the poloidal angle is the angular displacement in the plane R-Z made by a field line.…”

“…We will consider in this work a simple model that consists of five wire loops carrying electric currents, with the same relative position proposed in [9]…”

“…A model described by five parallel infinite wires was analyzed in [9], to simulate the magnetic surfaces of the tokamak ITER, in the presence of magnetic perturbations created by error fields due to asymmetries on the external coils [13,17]. Moreover, a Hamiltonian with three loop wires was analyzed in [10], to describe two mapping methods and to study the stochastic field lines in poloidal divertor tokamak plasmas affected by external non-axisymmetric magnetic perturbations.…”

“…On the other hand, simple models can delineate quite well dynamical properties of open and closed field lines near the separatrix. In particular, a simple way to delineate the MHD equilibrium magnetic field in tokamaks is to consider the magnetic configuration created by a set of coils or wires [9,10].…”