Neutron pinhole camera investigations on temporal and spatial structures of plasma focus neutron source

The neutron emission of the Frascati 1-MJ-plasma focus has been investigated over an energy range of 250 to 500 kJ by means of a neutron pinhole camera, using a six-channel detector array. Single-shot neutron streak images, space- and time-resolved, are obtained with an axial resolution of 2 cm and a time resolution of about 5 ns. – Results show that over 70% of the neutrons (i.e. more than 1011 neutrons per shot at 490 kJ) are emitted from a co-axial cylindrical volume about 4 cm long and less than 4 cm in diameter at the anode tip. Neither axial nor radial motion of this main source is observed throughout the emission lasting 200 ns FWHM typically. Simultaneous independent measurements show, for this zone, an isotropic neutron fluence (A = Φ (axial)/Φ (equat.) = 0.97 ± 0.04), while the energy spectra still are anisotropic as reported previously.