A Solid State Plasma

A solid state plasma, a lattice of beryllium ions (atoms from which 2 or 3 of the 4 electrons have been removed) remaining in solid state form for a few nanoseconds, has been studied by physicists at Livermore National Lab. This is done in two steps. First, intense x rays created by a powerful laser striking the outside of the coated beryllium sweep into the beryllium and strip electrons as they go by. But in the short time before the solid dissipates, a second laser striking a metal foil creates a beam of diagnostic x rays. The scattered x rays reveal an electron density of more than 2 x 10²³ per cubic centimeter and an electron temperature of 600,000 K. These conditions are hard to come by for plasmas in low-atomic-number atoms like beryllium and the hydrogen isotopes that will be the fuels in inertial confinement fusion. Siegfried Glenzer and his colleagues do their research as part of the lead-up to fusion work at the National Ignition Facility, where target pellets will undergo a compression up to 1000 times the normal solid state density. (Glenzer et al., Physical Review Letters, 2 May 2003; associated website, http://www.llnl.gov/nif/)