Astrophysical jets and solar loops in the lab

At the center of many an active galaxy lies an exceedingly powerful engine that, among other things, shoots out collimated jets of fast-moving plasma. Such jets can extend well beyond the galaxy’s luminous boundary, ending in vast lobes that light up the intergalactic medium in the radio band. Closer to home, the Sun’s atmosphere has many a plasma-filled magnetic loop, the dynamics of which are somewhat mysterious. In February, at the joint meeting of the American Physical Society and the American Association of Physics Teachers, Paul Bellan (Caltech) reported on his group’s recent experiments that shed light on both systems. The experimenters used the large currents and magnetic fields of spheromak technology to create plasma jets in a very large vacuum chamber, which ensured that the plasma configurations were unaffected by walls. With a preexisting magnetic field “frozen in,” the physicists puffed some gas through an electrode, switched on a...