Laboratory study of arched magnetic flux ropes formed within a solar-relevant potential field configuration*

Solar eruptive events such as coronal mass ejections (CMEs) are thought to be driven by a sudden release of magnetic energy stored in the solar corona. In many cases, the pre-eruptive configuration is a non-potential magnetic structure that can be modeled as a line-tied magnetic flux rope. In spite of ever-improving observations, directly studying these coronal flux ropes remains a significant challenge. As an alternative, we have designed a laboratory experiment to produce low-$\beta$ arched magnetic flux ropes similar to those found in the corona. These line-tied flux ropes are formed as a magnetized arc discharge between two electrodes and they evolve quasi-statically over hundreds of Alfv\'en times. Recently, we have constructed a new set of magnetic field coils to produce an active-region-like potential field configuration. Initial results from plasmas formed in this configuration are presented, including fast camera images and internal magnetic measurements. These discharges are expected to access a regime where a slowly evolving flux rope can suddenly undergo a dynamic eruption due to a loss-of-equilibrium\footnote{Forbes \& Isenberg, {\it ApJ} {\bf373}, 294 (1991)} or the torus instability.\footnote{Kliem \& T\"or\"ok, {\it PRL} {\bf96}, 255002 (2006)}