Re-appraisal and extension of the Gratton-Vargas two-dimensional analytical snowplow model of plasma focus - III: Scaling theory for high pressure operation and its implications

TL;DR

This paper extends the Gratton-Vargas model to develop a universal scaling theory for Dense Plasma Focus devices operating at high pressures, revealing that operational limits are due to technology, not physics.

Contribution

It introduces a scaling theory for high-pressure DPF operation based on a simplified model, expanding understanding beyond current low-pressure designs.

Findings

High-pressure DPF operation is limited by technological factors.

A velocity threshold related to gas ionization is identified.

The model enables optimization across a wide pressure range.

Abstract

Recent work on the revised Gratton-Vargas model has demonstrated that there are some aspects of Dense Plasma Focus (DPF) which are not sensitive to details of plasma dynamics and are well captured in an oversimplified model assumption which contains very little plasma physics. A hyperbolic conservation law formulation of DPF physics reveals the existence of a velocity threshold related to specific energy of dissociation and ionization, above which, the work done during shock propagation is adequate to ensure dissociation and ionization of the gas being ingested. These developments are utilized to formulate an algorithmic definition of DPF optimization that is valid in a wide range of applications, not limited to neutron emission. A universal scaling theory of DPF design optimization is proposed and illustrated for designing devices working at one or two orders higher pressure of deuterium than the current practice of designs optimized at pressures less than 10 mbar of deuterium. These examples show that the upper limit for operating pressure is of technological (and not physical) origin.