Density Distributions During the Neutron-Producing Phase of the Plasma Focus POSEIDON

Interferometric density measurements revealed the existence of various phases in the neutron emission of the POSEIDON plasma focus, i.e., a compression to a minimum diameter of about 15 mm, followed by a slightly expanded quiescent phase (25 mm in diameter), an instability phase, and finally, a decay of the dense plasma structures. Maximum densities are in the range of 1019 cm^-3. The double structure of the neutron pulses coincides with the following: 1) the compression to a minimum diameter; and 2) the later occurring instabilities. The estimated fraction of thermonuclear neutron production-in contrast to a rather complicated beam-target mechanism-amounts in both neutron pulses to less than 5%. This could be concluded using results of temperature measurements performed by laser scattering.