Pattern of the expansion of laser plasmas of various elements in a magnetic field

The expansion of laser plasmas of the elements Be, Al, Cu, and Pb in a static transverse magnetic field B≤2.7 T has been studied experimentally. The plasma was produced by a ruby laser at a power density no greater than 1012 W/cm2. For all the elements, a characteristic "two-petal" expansion pattern is observed. At a certain distance from the target, the two petals coalesce into a narrow jet. The radius of curvature of the petals and the position of the coalescence point depend on the field strength and the atomic weight of the element.