Number 270 (Story #3), May 9, 1996 by Phillip F. Schewe and Ben Stein|
RECORD HIGH LASER INTENSITY . The advent of tabletop terawatt lasers has promoted the study of new nonlinear optical effects. Donald Umstadter of the University of Michigan sends a powerful laser pulse into a sample of argon gas. The leading edge of the pulse rips electrons from the argon atoms. The rest of the pulse interacts with the ensuing plasma, setting up a self-focusing process which results in a laser intensity as high as 10**20 W/cm**2. Furthermore, the laser beam clears a micron-sized path for itself through the plasma. In the act of excluding plasma electrons from this region, pressures probably exceeding 1 giga-bar (higher than any other manmade pressure) are created. Umstadter, who spoke at the APS meeting, said that the high laser intensities might open new possibilities for the study of nonlinear optics. Another goal is the development of a tabletop accelerator for generating electrons with GeV energies (see Update 260).