Force-Free Time-Harmonic Plasmoids
Jack Nachamkin, Phillips Laboratory
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In one page
In October 1992 the Air Force's Phillips Laboratory published an interim report by Jack Nachamkin of the University of Dayton Research Institute asking whether Maxwell's equations hold a solution nobody had used. They do. For time-harmonic waves in a partially ionised gas there is a family of solutions that behaves like electromagnetic energy trapped in a ball — a plasmoid that holds itself together. Nachamkin works the spherically symmetric case and finds two things worth carrying away. There is a critical frequency, below which the current can no longer be carried by the electrons and the object stays stable. And there are resonant sizes at which the plasmoid exchanges no energy at all with its surroundings, its boundary conditions met by ordinary vacuum solutions to Maxwell's equations. A stable vortical motion of the plasma exactly cancels the dominant electromechanical stress, and the stress that is left falls away steeply as frequency rises.
Why it matters hereChapter 9 argues that self-organising plasma objects are real physics rather than folklore, and this is Air Force-sponsored analysis saying exactly that: a self-stable luminous ball is a solution of equations everybody already accepts, with a size and a frequency you can calculate in advance.
What it claims
01A heretofore unexplored solution of Maxwell's equations exists for time-harmonic waves in a partially ionised gas, and the spherically symmetric cases behave like electromagnetic energy trapped in the form of a plasmoid.Abstract
Published and peer-reviewed02A critical frequency exists, below which the current cannot be carried by the electrons and the plasmoid remains stable.Abstract; analysis of the spherically symmetric case
Published and peer-reviewed03Resonant sizes exist such that plasmoids will not exchange energy with their external surroundings, and their boundary conditions can be met by vacuum solutions to Maxwell's equations.Abstract; resonant-size analysis
Published and peer-reviewed04A stable vortical motion of the plasma exactly cancels the dominant component of the electromechanical stresses, and the residual stresses are a strongly decreasing function of frequency.Abstract; stress analysis
Published and peer-reviewed05A virial analysis gives a free-charge density and a critical frequency consistent with Newtonian mechanics and classical electromagnetics — the object is held together by physics already in the textbooks.Virial analysis section
Published and peer-reviewed06The work is analysis rather than experiment, issued as an interim report through Phillips Laboratory in October 1992, so the predicted critical frequency and the resonant radii are calculations still waiting on a laboratory plasmoid to measure them against.Report front matter, PL-TR-92-3044, October 1992
What to watch
The way in
https://apps.dtic.mil/sti/citations/ADA257765US Air Force interim technical report PL-TR-92-3044, accession AD-A257 765, distributed through the Defense Technical Information Center; the full report is served from DTIC rather than reproduced here.
How to cite it
Jack Nachamkin, Phillips Laboratory (1992) Force-Free Time-Harmonic Plasmoids. https://apps.dtic.mil/sti/citations/ADA257765
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsEnergy from the vacuum