Temperature mapping of compressed fusion pellets obtained by monochromatic imaging

We report the first use of toroidally bent crystals to record two‐dimensional, spatially resolved, monochromatic images of laser‐produced fusion plasma. The electron temperature was determined by seeding the deuterium fuel with argon and evaluating the intensity ratio of the two monochromatic images in the Ar+ 17Ly β and the Ar+ 16He β lines. Silicon and germanium crystals were chosen to achieve high diffraction reflectivities. Spatial resolution better than 10 μm was achieved by bending the crystals toroidally to minimize the geometrical aberrations [E. Forster, K. Gabel, and I. Uschmann, Laser Particle Beams 9, 135 (1991)]. Comparison of the two line intensities requires a calibrated imaging system. Monochromatic images of fusion pellets driven with the GEKKO XII glass laser system are presented.