THERMONUCLEAR PARTICLE IMAGING BY MAXIMUM-ENTROPY

MaXiMUM entropy techniques have been developed to image thermonuclear particle emission from laser driven implosions of DT filled microballoons. Spatial resolutions of 5-10 mum have been achieved using two separate techniques: maximum entropy deconvolution of penumbral images, and maximum entropy smoothed PNP (pseudo noise product) coded aperture images. The penumbral technique is generally capable of yielding higher resolution reconstructions. The analysis and fitting statistics have been developed to allow images to be obtained from the minimum number of particles. Rough images have been obtained from as few as 1 00 particles. These techniques can be extended to spectral images, and images of other particles such as X-rays in the case where the aperture function may be determined. The techniques are illustrated with a-particle and proton images obtained on the VULCAN laser at the Central Laser Facility, Rutherford Appleton Laboratory.