An alternative scaling model for neutron production in Z-pinch devices

Abstract

The DD neutron yield (Yn) from z-pinches, either dense plasma foci or fast radial pinches, has been fitted for decades to the scaling model Yn ∼ α(Imax)δ, where α is a numerical scaling coefficient, Imax the peak current, and 3 < δ < 5. The data from 12 000 pulses analyzed from eight different z-pinches presented in this paper show that Yn varies by as much as ±15 000% about the best fit value of the conventional scaling model with δ = 4. A revised scaling model derived from the reaction rate equation and a circuit model that includes the time derivative of the current dI/dt (normalized to its initial value) reduces the scatter in data from ±15 000% to ±100%. For the special case of very high normalized dI/dt, the standard deviation between the revised scaling prediction and the measured neutron yields is reduced to just ±30%. Implications of this revised scaling for higher current pinches are discussed.