Imaging of fusion protons from a 3 kJ deuterium plasma focus

This paper reports a study of the proton emission from a 3 kJ, 14 kV plasma focus device operated with deuterium gas at 400 Pa. A filtered pinhole camera with a 1.8 mm diameter hole is placed axially downstream of the plasma focus, and images of the proton-emitting region are recorded using CR-39/PM-355 nuclear track detectors. The detector plates are scanned using an automated track measurement system and the spatial track density profile is acquired. The resulting density distribution is interpreted with the help of a simple pinhole imaging model that assumes the 2H(d, p)H-3 reaction protons are emitted from a conical region extending from the tip of the anode to a fixed distance downstream. Comparison of the experimental track density profile with the model calculations supports the view that the beam-target mechanism is the dominant fusion production mechanism in this small plasma focus device.