Efficient neutron production from a novel configuration of deuterium gas-puff z-pinch.

A novel configuration of a deuterium $z$ pinch has been used to generate fusion neutrons. Injecting an outer hollow cylindrical plasma shell around an inner deuterium gas puff, neutron yields from DD reactions reached ${Y}_{\mathit{n}}=(2.9\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}1{0}^{12}$ at 700 ns implosion time and 2.7 MA current. Such a neutron yield means a tenfold increase in comparison with previous deuterium gas puff experiments at the same current generator. The increase of beam-target yields was obtained by a larger amount of current assembled on the $z$-pinch axis, and subsequently by higher induced voltage and higher energies of deuterons. A stack of CR-39 track detectors on the $z$-pinch axis showed hydrogen ions up to 38 MeV. Maximum neutron energies of 15 and 22 MeV were observed by radial and axial time-of-flight detectors, respectively. The number of DD neutrons per one joule of stored plasma energy approached $5\ifmmode\times\else\texttimes\fi{}{10}^{7}$. This implies that deuterium gas puff $z$ pinches belong to the most efficient plasma-based sources of DD neutrons.