K_α fluorescence measurement of relativistic electron transport in the context of fast ignition

The energy transport properties were investigated within a dense plasma using a K_α fluorescence layer. A spherically bent Bragg crystal monochromatic two-dimensional (2D) x-ray imaging technique was utilized to record the origin of K_α photons created in a 20 μm thick buried Ti or Cu fluor layer in a planar Al or CH target. It was found that one or more processes cause lower energy electrons to travel at very large angles very near the front surface of the target. The results show that laser generated electrons penetrating through more than 100 μm of Al, emerge from a >150 μm wide region and travel in a 40° full-width cone.