Hydrodynamic Symmetry and Stability of a Heavy Ion BeamDriven Planar Icf Target.
Abstract
The twodimensional hydrodynamic stability and symmetry of a directdriven planar inertial confinement fusion (ICF) target irradiated by a heavy ion beam is investigated in a fourstep process. First, critical reviews and extensions of current theory are presented for hydrodynamic stability theory and its application to symmetry and stability problems in ICF (i.e., a new interpretation of limiting spike motion in the nonlinear RT instability), analytical theory of beamcoupled hydrodynamics (i.e., a new steadystate 1 D model), and chargedparticle slowingdown theory (i.e., recognition of the applicability of the unified slowing down theory). Second, a selfconsistent twodimensional particleincell (PIC) representation of the ion beamtarget interaction and hydrodynamic response is developed. This model, known as FLIP (fluid implicit particle), was developed specifically for the accurate modeling of unstable and distorted hydrodynamic flow in ion beamdriven ICF targets. Third, the PIC numerical model is studied, verified, and tested by comparison with exact analytic solutions and other published calculations. Fourth, the numerical model is used to study the hydrodynamic response of a tamped, HIBALLlike planar ICF target in two dimensions. Twodimensional hydrodynamic flow of the planar HIBALL ICF target is numerically studied for the following cases: (1) an initially uniform target imploded by a normally incident, 10 GeV Bi^+ beam with a spatially uniform, timedependent intensity (2) an initially uniform target imploded by a normally incident, 10 GeV Bi^+ beam with an intensity perturbed in a direction lateral to the beam propagation; and (3) an initially nonuniform target imploded by a normally incident, 10 GeV Bi^+ beam with a uniform intensity. Beam intensity perturbation wavelengths close to target shell thicknesses appear to have the most disastrous effects on implosion symmetry. Tolerable beam intensity perturbation amplitudes depend on the zero order intensity (510% at 1 TW/cm^2 and 1% at 1000 TW/cm^2 for intensities constant in time). Reactor beam pulses may possibly result in a target more tolerable to asymmetries. Initial surface perturbations in the planar HIBALLlike target irradiated at 1 TW/cm^2 were the most disastrous for those imposed at the tamper/absorber interface. Perturbation growth at the pusher/fuel interface appears to be more easily predicted and less complicated than in laserdriven targets.
 Publication:

Ph.D. Thesis
 Pub Date:
 1987
 Bibcode:
 1987PhDT.......152K
 Keywords:

 Physics: Fluid and Plasma