Photoneutron production accompanying plasma disruptions in JET

Abstract

The strength of the photoneutron emission accompanying major plasma disruptions in JET has been studied for the period from startup to December 1986. The observed photoneutron yields cover the range from 1010 to 1015 neutrons, with instantaneous intensities reaching 5 × 10l7 neutrons⋅s−1. It is shown that the energies attained by runaway electrons can be very high, perhaps exceeding 100 MeV, so that the runaway currents of high energy electrons are significant, sometimes exceeding 1 MA, and, on average, the fraction of the available magnetic energy converted to high energy runaway electron production is f = 2.9 × 10−2 Ip0.6, with the plasma current Ip in MA.