Research with High-Power Short-Wavelength Lasers
J. F. Holzrichter 1,
E. M. Campbell 2,
J. D. Lindl 3, and
E. Storm 4
1 Iinertial fusion direction and laser research., Lawrence Livermore National Laboratory, Livermore, California 94550.
2 Laser-plasma experiments and diagnostics., Lawrence Livermore National Laboratory, Livermore, California 94550.
3 Theory and numerical modeling., Lawrence Livermore National Laboratory, Livermore, California 94550.
4 Inertial confinement fusion experiments and direction., Lawrence Livermore National Laboratory, Livermore, California 94550.
Three high-temperature, high-density experments were conducted recently with the 10-terawatt, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. The experiments demonstrated successful solutions to problems that arose during previous laser-plasma interaction experiments with long-wavelength (greater than 1 micrometer) lasers: (i) large-scale plasmas, with dimensions approaching those needed for high-gain inertial fusion targets, were produced in which potentially deleterious laser-plasma instabilities were collisionally damped; (ii) deuterium-tritium fuel was imploded to a density of 20 grams per cubic centimeter and a pressure of 1010 atmospheres under the improved laser conditions, and compression conditions (preheating and pressure) were consistent with code calculations that predict efficient (high-gain) burn of a large thermonuclear fuel mass when driven with a large, short-wavelength laser; and (iii) soft x-rays were amplified by a factor of 700 by stimulated emission at 206 and 209 angstroms (62 electron volts) from selenium ions in a laser-generated plasma. These small, short-pulse x-ray sources are 1010 to 1011 times brighter than the most powerful x-ray generators and synchrotron sources available today. The plasma conditions for these experiments were made possible by advances in Nd:glass laser technology, in techniques to generate efficiently its short-wavelength harmonics at 0.53, 0.35, and 0.26 micrometers, and in diagnostic and computational modeling.
