Generation of astrophysics-relevant helical magnetic structures in laser-produced plasma

Abstract

Helical magnetic fields play an important role in star formation and stellar wind shaping. In recent years, there have been many experiments using pure poloidal or toroidal fields to confine hot plasma species that have successfully reproduced jets and instability patterns similar to those in the universe, but the role of helical magnetic structures is rarely explored due to the complexity of their generation. However, certain processes like cloud angular momentum extraction will only manifest in helical field configurations. In this article, we propose and numerically illustrate a method that can generate helical magnetic structures inside the plasma by merging a self-generated toroidal field and an externally applied poloidal field. The resulting helical field is dynamically important regarding pressure, adjustable in strength and pitch angle, and consistent with the actual astrophysical outflow in terms of boundary conditions. This method shows how to integrate a helical field structure into laser-plasma experiments, and it provides a framework for future studies on stellar outflow interaction with their embedded helical fields.