Magnetically nozzled plasma accelerators for advanced manufacturing

Abstract

The coaxial plasma accelerator is a simple, efficient, compact, and mechanically robust device that utilizes the Lorentz J×B force to accelerate plasma to high velocity. Originally developed in the 1950s for the purpose of providing energetic plasmas for fusion energy experiments, coaxial plasma accelerators are presently being investigated as an environmentally sound and economical means of materials processing and advanced manufacturing. While commercial applications of this technology are already on line, future commercial applications will likely require improving accelerator reproducibility and better controlling the accelerated plasma flow velocity or energy, and the distribution of directed energy or power on a downstream target. At the Los Alamos National Laboratory, we have investigated the interaction of magnetic nozzles, composed of well-shaped magnetic fields, with accelerated plasma and have shown that these magnetic nozzles hold great promise in enabling the control capabilities necessary for future industrial applications. Conceptually, the magnetic nozzle controls plasma flow analogous to gas-dynamic nozzles, where the nozzle shape affects flow velocity and flow streamline distributions both within and downstream of the accelerator. Ongoing research is exploring the effects of magnetic nozzles on coaxial plasma accelerator operation with a view toward optimizing these devices for large area surface treatment applications.