The LASL Fast Liner Experiment

The LASL Fast Liner Experiment explored a fusion concept in which a suitably prepared plasma is adiabatically compressed to thermonuclear temperatures and densities by a rapidly imploding solid metal liner. A prepared plasma having β>1 is in contact with the liner and end plugs, and contains an embedded magnetic field to inhibit thermal conduction. Cylindrical liners are magnetically imploded by a large axial current carried in the liner shell. The experimental work to develop this concept involved attempts to provide a suitable plasma for liner implosions and studies of magnetically driven liner implosions. In the plasma preparation experiments, a coaxial plasma gun was used to inject plasma into a simulated liner geometry. About 2μs after plasma injection a density of 3x1016cm-3, a temperature of 40eV, and an embedded azimuthal field of 10kG were measured. In the implosion studies, cylindrical aluminium liners were imploded by Z-pinch currents of 10-15MA. Symmetrical implosions having velocities in the range 4-6x105cm.s-1 have been obtained for liners with typical initial dimensions of 10cm length, 5cm diameter and 1mm thickness using a 1.8-MJ capacitor bank. Implosion velocities of 9-10x105cm.s-1 were observed for 6-cm-long, 5.6-cm-diameter, 1-mm-thick liners driven by a 2.4-MJ bank. In each case, current drive to the liner was maintained until the liner converged on the axis. The observed velocities and trajectories agree well with the predictions of a one-dimensional code, CHAMISA. (author)