Plasma Generates Surprising Patterns

Sometimes patterns form spontaneously in unexpected places, such as the washboard pattern on a dirt road, or the stripe formations of certain clouds, and it's the job of physicists to figure out why. In the 27 May Physical Review Letters, a team reports another surprising pattern--discovered accidentally--and tries to explain it. They show that a plasma in a magnetic field develops filaments that form a range of structures, including quasi-crystalline structures, spirals, and concentric circles. The appearance of structure could have implications for the future use of plasmas in industrial settings, and the technique for visualizing the structures might also be used by others to study the internal motions within plasmas.