High-resolution imaging of early-time imprinting using normal-incidence multilayer mirrors. Final report

Abstract

A normal-incidence multilayer mirror telescope was designed, fabricated, and tested. The telescope consisted of a primary mirror and a secondary mirror in a Cassegrain optical configuration. The mirrors had multilayer coatings that efficiently reflected the soft x-ray radiation in a narrow bandpass centered at a wavelength of 48 {angstrom}. The telescope was taken to the Laboratory for Laser Energetics (LLE) on October 28, 1996. The telescope was mounted in a TIM instrument module on the OMEGA target chamber. The focusing and alignment of the mirrors were checked and optimized. Images were recorded on x-ray film on October 30. Images were recorded on a gated framing camera on October 31 and November 1. On each laser shot, hard x-ray images were recorded by a pinhole camera and a gated framing camera. The soft and hard x-ray images were returned to NRL for analysis. The images were digitized and compared. The major result of the study was that the soft x-ray emission from plasmas generated by 6 to 8 overlapping OMEGA beams is quite uniform, even for the case when beam smoothing techniques were not implemented. This implies that the soft x-ray emission can be used for backlighter applications and for the study of absorption by CH foils in the 48 {angstrom} wavelength region, at slightly longer wavelengths than the carbon K absorption edge where carbon is relatively transmissive. These backlighter techniques are now being implemented at LLE.