Hard x-ray bursts observed in association with Rayleigh-Taylor instigated current disruption in a solar-relevant lab experiment

Measurements by multiple X-ray detectors show transient emission of a 1 μs pulse of non-mono-energetic ∼6 keV X-rays by a cold, dense MHD-driven plasma jet. Because the collision mean free path is much smaller than the jet dimensions, the acceleration of particles to high energy was not expected. The X-ray pulse occurs when the jet undergoes a kink instability which accelerates the jet laterally so that a fast-growing secondary Rayleigh-Taylor instability is triggered which then breaks the jet. The jet breaking is correlated in time with several other fast changing phenomena. It is proposed that despite the short collision mean free path, an inductive electric field associated with this breaking accelerates a certain subgroup of electrons to keV energies without any of these electrons undergoing collisions. It is further proposed that after being accelerated to high energy, these fast electrons are suddenly decelerated via collisions and radiate X-rays. ; © 2018 Published by AIP Publishing. Received 5 September 2018; accepted 14 October 2018; published online 1 November 2018. We would like to thank Professor Gunsu S. Yun of Pohang University of Science and Technology in Pohang, South Korea, for bringing and operating D_(amptek) on the jet experiment at Caltech. D_(amptek) provided valuable qualitative results. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences, under Award No. DE-FG02-04ER54755 and by the Air Force Office of Scientific Research under Award No. FA9550-11-1-0184. Experimental data are available at https://data.caltech.edu/records/305. ; Published - 1.5054927.pdf