Experimental investigation of fast electron transport through Kα imaging and spectroscopy in relativistic laser–solid interactions

Abstract

The study of the basic physical processes underlying the generation of fast electrons during the interaction of high-intensity short laser pulses with solid materials and the transport of these fast electrons through the target material are of great importance for the fast ignition concept for inertial confinement fusion and for the development of ultra-short X-ray sources.We report on the experimental investigation of fast electron transport phenomena by means of the spatial and spectral characterization of the X-ray emission from layered targets using bent crystal spectrometers and a new diagnostic technique based on a pinhole-camera equipped with a CCD detector working in single-photon regime for multi-spectral X-ray imaging [1]. In particular, differences of fast electron transport features depending on the atomic number and/or the resistivity of the target material have been studied.The experiments were carried out at relativistic laser intensities, both in the longer (≃ps) pulse interaction regime relevant for fast ignition studies [2] and in the short-pulse (≃100 fs) interaction conditions related to basic physics studies as well as to the development of ultrashort Kα X-ray sources.

Experimental study of K-shell X-ray emission generated from nanowire target irradiated by relativistic laser pulses

“…2 are Kα 1 (0.15406 nm) and Kα 2 (0.15444 nm), respectively. The integrated peak intensity ratios of Kα 1 and Kα 2 both satisfy Iα 1 /Iα 2 ∼ 2, which agrees with previously reported results [15] . Still in the raw dispersion spectrum, no continuous radiation is obtained (Fig.…”

Temperature profiles derived from transverse optical shadowgraphy in ultraintense laser plasma interactions at 6×1020 W cm−2

“…X-ray diagnostics included x-ray pinhole imaging, Cu K␣ imaging with a spherical crystal, and a mica crystal spectrometer. 9 The expansion on the front and back surfaces of the target was diagnosed using a transverse optical probe. The 1.054 m light was frequency doubled to 527 nm using a potassium dihydrogen phosphate crystal.…”

HiPER laser: from capsule design to the laser reference design

“…Preliminary experimental studies of key issues concerning hot electron generation and transport in a low-intermediate density plasma and the interaction between cone and spherical shell have begun [20][21][22] but not yet addressed in the full needed detail. We are currently developing the necessary tools (including computer codes and the required development [23]).…”