Lasers used to study plasmas denser than sun's

17 Jun 2002

Probing artificial plasmas six times denser than the center of the sun is the goal of scientists working on the proposed National Ignition Facility (NIF), a U.S. research center where scientists plan to study nuclear fusion and other processes involving extremely dense plasmas. NIF plans to use high-power lasers to achieve, among other things, inertial confinement fusion, in which a deuterium-tritium (D-T) fuel pellet is compressed to extremely high densities.

In experiments that aim to achieve self-sustaining fusion reactions, the densities are expected to reach up to 1000 grams per cubic centimeter, the densest conventional plasmas ever to exist on Earth. To determine what goes on at the center of such hard-to-penetrate plasmas, researchers at MIT, Livermore, and University of Rochester have proposed studying "tertiary protons," which are created at the end of a three-step process starting with the fusion of deuterium and tritium nuclei. These tertiary protons would be energetic enough (~30 MeV) to escape the dense plasma and reach a network of detectors. Energy losses of protons emerging from all different directions can show whether the fuel pellet compresses uniformly and also yield information on the density and size of the region in which fusion occurs., according to an article in the Physical Review Letters.