Update on the Scientific Status of the Plasma Focus

Abstract

This paper is a sequel to the 1998 review paper “Scientific status of the Dense Plasma Focus” with 16 authors belonging to 16 nations, whose initiative led to the establishment of the International Center for Dense Magnetized Plasmas (ICDMP) in the year 2000. Its focus is on understanding the principal defining characteristic features of the plasma focus in the light of the developments that have taken place in the last 20 years, in terms of new facilities, diagnostics, models, and insights. Although it is too soon to proclaim with certainty what the plasma focus phenomenon is, the results available to date conclusively indicate what it is demonstrably not. The review looks at the experimental data, cross-correlated across multiple diagnostics and multiple devices, to delineate the contours of an emerging narrative that is fascinatingly different from the standard narrative, which has guided the consensus in the plasma focus community for several decades, without invalidating it. It raises a question mark over the Fundamental Premise of Controlled Fusion Research, namely, that any fusion reaction having the character of a beam-target process must necessarily be more inefficient than a thermonuclear process with a confined thermal plasma at a suitably high temperature. Open questions that need attention of researchers are highlighted. A future course of action is suggested that individual plasma focus laboratories could adopt in order to positively influence the future growth of research in this field, to the general benefit of not only the controlled fusion research community but also the world at large.

Towards real-time oxygen sensing: From nanomaterials to plasma

“…In a multi-step combustion mechanism with known operating conditions (such as H 2 , O 2 , HO 2 , H + , OH − , HO 2 , O 2+ , and δ is the third body in our simulation), the concentration of oxygen is found from the rate equations of other species involved in the system 78 61 ). 4, Plasma discharges in pure neon (adapted from 68 ). 5, Effect of liners in PF discharge (adapted from 68 ).…”

“…8, Electric circuit of nitrogen-plasma jet device (adapted from 61 ). 9, Real-time plasma from an RIE setup (adapted from 70 10, Electron density profiles at 3 different distances from the anode plane (adapted from 68 ). 11, FEM simulated electron density vs position of candle flame.…”

“…(adapted from61 ). 4, Plasma discharges in pure neon (adapted from68 ). 5, Effect of liners in PF discharge (adapted from68 ).…”

“…4, Plasma discharges in pure neon (adapted from68 ). 5, Effect of liners in PF discharge (adapted from68 ). 6, An air plasma generation setup (adapted from64 ).…”

On filamentation in the dense plasma focus

“…The present paradigm of plasma focus research can be succinctly summarized in terms of a Standard Narrative [3]. Its chief defining characteristic feature is a travelling distribution of current (that can be initiated by a variety of mechanisms [3], but is most commonly initiated by a sliding discharge on an insulator) accelerated by its own magnetic field that drives an ionizing shock wave into the neutral fill gas, mainly deuterium, and its subsequent convergence into a dense and hot plasma column. Physical separation of the current distribution (measured using magnetic probes) and the dense shockwave plasma (that is seen in most emissivity and refractivity-based diagnostics) is a well-established fact.…”