Ultrafast Framing Of X-Ray Images

Abstract

The interaction of pulsed, high-intensity (I>10¹⁴ W/cm2) laser light with a solid target typically produces a dense plasma that radiates significantly in the soft x-ray region of 0.1-10 keV.1 Important information concerning the dynamics of the laser-produced plasmas can be obtained through time-resolved imaging and spectroscopy of the x-ray emission. In particular, high-resolution x-ray imaging provides a direct means of studying the evolution of temperature and density profiles of the plasma, as well as the hydrodynamics which govern its expansion. Since the expansion velocities can be in excess of 107 cm/s, the frame duration of the time-resolved image must be less than 100 ps to avoid significant blurring. In addition, the laser-produced plasmas are usually small and have large density gradients, particularly at early times. Consequently, it is desirable that the imaging system be able to resolve structure on a spatial scale of 1-10 μm. In this paper we describe the development of a high resolution x-ray framing cameral (XFC) to be used to image the soft x-ray emission from laser-produced plasmas on a picosecond timescale. The XFC generates a single frame with 50 ps temporal resolution 22 pm spatial resolution at the image plane and real time readout. The camera is optically triggered, resulting in jitter-free synchronization of the frame time with the laser experiment, making it possible to integrate multiple shots with no loss of temporal resolution. One of the first applications of the XFC will be to image the dynamic implosion of micro-balloon fuel pellets for laser fusion using the Nova 10-beam laser system.