(a) Sketch of the experimental setup. CSA is a circular soft aperture. OPM is an off-axis parabolic mirror. IP is the image plate with 20 cm height and 15 cm (first), 12.5 cm (second), and 12.5 cm (third) length. Some part ( length) of the first image plate is shadowed by the second image plate. The first image plate and the other two IPs are not placed at the same height. (b) Contrast ratio of the incident laser pulse. (c) Laser focus spot.
Angular distributions of hot electrons generated by the -polarized laser irradiated grating targets at 25° (a), 30° (b), 35° (c), 40° (d), and 45° (e) incident angles, and by a flat solid Al target at 25° incident angle (f). From left to right are, in turn, the electron images on the first, second, and third IP, respectively. Note that the first IP and the other two IPs are not placed at the same height and some part of the first IP is shadowed by the second IP. Angular distribution curves (insets) adopt the average intensity in the effective region. The laser incident direction is at 0° angle (labeled with arrows). Solid lines denote the target normal direction and the specular reflection direction.
The counts on IP of the collimated hot electron jet at the specular reflection direction and the spreading hot electrons emitting along the normal direction vs incident angle. The data are taken from Fig. 2 and integrated in the entire signal region.
Spatial distribution of initial electron density [(a) and (d)], transverse electric field amplitude [(b) and (e)], and longitudinal electric field amplitude [(c) and (f)] at . [(a)–(c)] are for the grating target, and [(d)–(f)] are for the flat target. For the grating target in (a)–(c), the electrons and ions in the region of and are removed. This does not affect the laser-grating target interaction. The scale unit is micrometer.
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