Polar Angle Fluence Distribution Measurements Using Fast Total Stopping Calorimeters

Alameda Applied Sciences Corporation (AASC) proposes to adapt a commercially available instrument called a Laser Wavefront Analyzer (LWA) to capture snap-shots of the current and density in the initial coronal region of an imploding z-pinch on the 0.7 MAHawk accelerator at NRL. These snap-shots will reveal the structure of instabilities in the formation of the pinch and allow us to correlate improved power coupling to the pinch and higher radiation efficiency. The LWA, based on the Shack-Hartmannprinciple, works by traversing a collimated and P-polarized laser pulse across the z-pinch. The plasma distorts the laser wavefronts and the polarization vector rotates due to the density and magnetic field vectors. After the pinch, the beams are splitinto orthogonal S and P polarized beams and the distorted wavefronts are focused by a 200x200 micro-lens array. The intensities and positions of these focused micro-beamlets are captured by CCD cameras. From the captured images, it is possible toreconstruct the plasma density (from position shifts) and the magnetic field/implosion current (from intensity variations). In Phase-II, an upgraded LWA may be used to obtain the density profiles around the corona and core pinch plasmas and the implosioncurrent in the core plasma.The LWA can capture images of shock phenomena in combustion flows and also resolve inter-phase vapor-liquid droplet phenomena in rocket nozzles and other fuel mixtures. The LWA is also useful as an optical diagnostic tool influid mechanics, with applications in heat flow, turbulence and droplet evaporation. The LWA may also be widely used in defense adaptive optical imaging and transmission applications.