On the failure of neutron yield scaling in the dense plasma focus

Abstract

The observed scaling of neutron yield in the dense plasma focus (DPF) as the fourth power of the current in the plasma was the principal driver of the growth of DPF research in its early days. Subsequent discovery of failure of this scaling law was also the principal reason for its abandonment by major laboratories. Attempts to understand this failure of scaling have so far been inconclusive. This Letter looks at this failure in the context of the recently introduced the Generalized Plasma Focus problem and suggests a possible reason that can be experimentally examined using small plasma focus devices. This involves restrictions placed on the drive parameter by conservation laws for mass, momentum, and energy. A suggested empirical workaround to the problem of neutron yield scaling failure could also be configured as a method for increasing the pressure range for neutron emission in small DPF devices.