Confirmation of the Growth of Cosmic Plasma Filaments

Filaments consisting of electrical current, magnetic fields and spinning plasma are central to the operation of the dense plasma focus. They constitute the critical first step in concentrating energy that leads to the formation of dense, hot plasmoids where fusion reactions take place. The theoretical and experimental understanding of such filaments was first pioneered by Nobel Laureate Hannes Alfvén and his collaborator Carl-Gunne Falthammar in the early 1980’s. These researchers connected phenomenon observed in laboratory experiments with those observed on the astrophysical scales of stars and galaxies. LPP Fusion Chief Scientist Eric Lerner elaborated this work in 1986 into a quantitative theory of how such filaments originated in the evolution of the cosmos and interacted with gravitation to form the structure of planets, stars, galaxies, cluster of galaxies and superclusters that we see today.

These theories were and remain controversial because the time required to from the largest-scale filaments is trillions of years, hundreds of times longer than the time since the hypothesized Big Bang. We will be reporting on new developments in the debate over the Big Bang hypothesis in coming months.

But now new research and detailed supercomputer simulations have confirmed the idea that large scale magnetic filaments can arise from cosmic plasma—without needing either a Big Bang or any pre-existing magnetic fields. A team of researchers at MIT, Princeton, the University of Colorado and the Flatiron Institute in New York City have published in the Proceedings of the National Academy of Science on May 5 a paper showing that magnetic fields form at all scales through the filamentation instability (also called the Weibel instability)  in any plasma that has shear. Shear simply means any sort of internal motion in which particles are not all moving in exactly the same direction—something that is inevitable in any real plasma.

The team first showed analytically (by exact equations) that a magnetic field will build up quickly on time scales similar to the “crossing time” of the plasma—the time it takes particle to move from one side to another of the plasma. Then they used a particle-in-cell simulation to verify their calculations. Such PIC simulations trace a sample of charged particles through a grid of cells and can be very accurate, although they require big supercomputers. The simulations did indeed show filaments appearing from a previously unmagnetized plasma (see Fig. 3)

Sim cosmicplasma | lpp fusion

Figure 3. These images from the new simulations show the growth of filaments, already underway in the image at left, continues at later times. The times are fractions of the crossing time.

This is yet another dramatic confirmation of the general model for structure formation laid out decades ago by Alfvén and Falthammar. The study did not contain any gravitation, so the full process of structure formation could not be studied, but it did show the initial stages, before the magnetic filament had grown to the size where gravitation would become important.

The authors also did not note that the timescales indicated in their studies would only allow for the formation of magnetic fields on the scale of about 15 Mpc during the 14 billion years since the hypothetical Big Bang. But filamentary structures on far larger scales—up to 3Gpc—have already been observed, adding to the evidence that object in the universe exist that are hundreds of times older than the Big Bang hypothesis allows.

The published article is here, but a free version is here.









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