Modelling loop-top X-ray source and reconnection outflows in solar flares with intense lasers

Magnetic reconnection is a process by which oppositely directed magnetic field lines passing through a plasma undergo dramatic rearrangement, converting magnetic potential into kinetic energy and heat(1,2). It is believed to play an important role in many plasma phenomena including solar flares(3,4), star formation(5) and other astrophysical events(6), laser-driven plasma jets(7-9), and fusion plasma instabilities(10). Because of the large differences of scale between laboratory and astrophysical plasmas, it is often difficult to extrapolate the reconnection phenomena studied in one environment to those observed in the other. In some cases, however, scaling laws(11) do permit reliable connections to made, such as the experimental simulation of interactions between the solar wind and the Earth's magnetosphere(12). Here we report well-scaled laboratory experiments that reproduce loop-top-like X-ray source emission by reconnection outflows interacting with a solid target. Our experiments exploit the mega-gauss-scale magnetic field generated by interaction of a high-intensity laser with a plasma to reconstruct a magnetic reconnection topology similar to that which occurs in solar flares. We also identify the separatrix and diffusion regions associated with reconnection in which ions become decoupled from electrons on a scale of the ion inertial length.