High-Energy Particles in Solar Flares

Abstract

AT a recent lecture delivered at Harwell, Dr. I. V. Kurchatov gave details of Russian experiments with high current-density gas discharges. One interesting phenomenon that was observed concerned the production of high-energy particles in the discharge, possessing energies greatly in excess of those that could be attributed to the Maxwellian distribution at the temperatures reached in the spark, and also greatly in excess of the electron-energy corresponding to the potential difference across the spark gap. This effect could be observed in deuterium through the production of neutrons and gamma-rays. The onset of this phenomenon was always clearly related to a certain behaviour of the spark, namely, to the second constriction that occurred. It must therefore be supposed that in the complicated electrodynamical processes that occur in sparks that become constricted in their own magnetic field, there occurs a mechanism for accelerating a small fraction of the particles to high energies. This can perhaps be understood in terms of multiple reflexions of ions in the interior of a rapidly converging cylindrical magnetic shock wave.