HYDRODYNAMIC STABILITY AND THE DIRECT DRIVE APPROACH TO LASER FUSION

In order for inertial confinement fusion (ICF) capsules to achieve high gain, they must not break up because of hydrodynamic instability, the fuel should be maintained on a low adiabat, and the peak laser intensities should be below thresholds of various plasma instabilities. In this paper the results of two-dimensional computer calculations modeling the growth of hydrodynamic instabilities of slabs directly driven with a laser are reported. In order for direct drive capsules to succeed with capsule finishes of 100-300 Å, the capsules must be imploded on an adiabat a factor of 3-4 in pressure above a Fermi-degenerate adiabat or techniques must be developed for producing density gradient scale lengths of about half the shell thickness. These conclusions depend only weakly on the laser intensity. © 1990 American Institute of Physics.