arXiv subjects

A. I. Kuiroukidis

Publications and source records attributed to A. I. Kuiroukidis.

4 recordsLinked to original sources

arXiv2026

A special exact class of three-dimensional equilibria of a magnetized plasma exhibiting closed and nested toroidal magnetic surfaces

We construct a special class of three-dimensional (3D) equilibria with pressure anisotropy which showcase closed, nested toroidal magnetic surfaces that are strongly asymmetric in the toroidal direction by applying a sinusoidal perturbation to the axisymmetric Solov'ev equilibrium. They also exhibit distinct closed and nested current-density surfaces. For certain values of the free parameters involved, the perturbations lead to the formation of magnetic islands and stochastic areas in the outer plasma region, while well-defined magnetic surfaces persist in the inner region. In addition, it is demonstrated that the existence of closed and nested surfaces within the plasma region on which the magnetic field modulus is uniform (isomagnetic surfaces) is neither necessary nor sufficient for the existence of respective closed and nested magnetic surfaces.

physics.plasm-ph↗

arXiv2025

Hybrid fluid-kinetic cylindrical equilibria with axial background magnetic field

Self-consistent, one-dimensional quasineutral screw-pinch equilibria are constructed within a hybrid model that couples fluid electrons with kinetic ions governed by the Vlasov equation. The equilibria depend on the radial coordinate perpendicular to the cylindrical axis and include an axial background magnetic field. Adopting a three-parameter ion distribution function depending on the energy and the canonical momenta conjugate to the two ignorable coordinates, the problem is reduced to a set of four quasilinear ODEs which are solved numerically. Both static equilibria and equilibria with macroscopic ion sheared velocities are obtained. The pressure of the electron fluid is isotropic and the electron contribution to the current density is parallel to the magnetic field, while the kinetic ions are associated with a non-gyrotropic pressure tensor. By means of the solutions the various equilibrium quantities are calculated and the impact of the free parameters on the equilibrium characteristics is examined.

physics.plasm-ph↗

arXiv2025

New axisymmetric equilibria with flow from an expansion about the generalized Solov'ev solution

We construct analytic solutions to the generalized Grad-Shafranov equation, which incorporates both toroidal and poloidal flows. This is achieved by adopting a general linearizing ansatz for the free-function terms of the equation and expanding the generalized Solov'ev solution [Ch. Simintzis, G. N. Throumoulopoulos, G. Pantis and H. Tasso, Phys. Plasmas {\bf 8}, 2641 (2001)]. On the basis of these solutions, we examine how the genaralized Solov'ev configuration is modified as the values of the free parameters associated with the additional pressure, poloidal-current and electric-field terms are changed. Thus, a variety of equilibria of tokamak, spherical tokamak and spheromak pertinence are constructed, including D-shaped configurations with positive and negative triangularity and diverted configurations with either a couple of X-points or a single X-point.

physics.plasm-ph↗

arXiv2024

A similarity reduction of the generalized Grad-Shafranov equation

We extend previous work [Y. E. Litvinenko, Phys. Plasmas 17, 074502 (2010)] on a direct method for finding similarity reductions of partial differential equations such as the Grad-Shafranov equation, to the case of the generalized Grad-Shafranov equation (GGSE) with arbitrary incompressible flow. Several families of analytic solutions are constructed, the generalized Solovév solution being a particular case, which contain both the classical and non-classical group-invariant solutions to the GGSE. Those solutions can describe a variety of equilibrium configurations pertinent to toroidal magnetically confined plasmas and planetary magnetospheres.

physics.plasm-ph↗