Analysis of Imploded Capsule Images from Spherical Hohlraums with Tetrahedral Illumination

Tetrahedral hohlraums (spherical hohlraums with four laser entrance holes) have potential advantages over cylindrical hohlraums for symmetric implosion of ICF capsules.(J. D. Schnittman and R. S. Craxton, Phys. Plasmas 3, 3786 (1996).)(D. W. Phillion and S. M. Pollaine, Phys. Plasmas 1, 2963 (1994).) Experiments have been performed at the OMEGA Laser Facility in which ``standard'' capsules have been imploded using tetrahedral hohlraums. The fuel of the capsule was doped with Argon to allow x-ray images of the imploded core to be obtained. The lowest order mode in an ideal tetrahedral experiment is the Y_3,2 mode so that the dominant asymmetry in the image is expected to be an m=3 mode. The distortion is defined as the ratio of the maximum to the minimum radius and is designated d₃ ≡ (A_0+A_3)/(A_0-A_3) where A_n is the amplitude of the m=n Fourier component of the x-ray emission contour.