Correlation of Radiation With Electron and Neutron Signals Taken in a Plasma-Focus Device

Abstract

In the PF 1000 plasma-focus device, deuterium is used as a filling gas for the study of fast neutrons (originated from D-D fusion reactions) and X-rays. The X-ray signals have two peaks. The first peak corresponds to the time of the minimum diameter of the pinch phase, as recorded by the visible frames. The second peak has its maximum 150 to 200 ns later. The electrons with energy above a few hundreds of kiloelectronvolts are registered mostly at the first peak in both axial directions. Upstream and downstream electrons differ in their intensity (ratio 3 : 1), temporal profile, and time of their maximum. The energy of the neutrons and the time of their generation are determined by the time-of-flight method using six or seven scintillation detectors positioned in the axial direction. Each neutron pulse has a dominant portion of beam-target origin with downstream energies up to 3.2 MeV and the final portion of the neutrons with energies in the range of 2.2 to 2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream motion of the intense radiating axis layer of the pinch and with the forming and existence of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the exploding of the plasma after the second pinching, and with the forming and existence of the structure of the dense plasma at the bottom of the dilating current sheath, which is similar to the first pulse