Intense particle beams generated from the interaction of ultrahigh intensity lasers with sample foils provide options in radiography, high-yield neutron sources, high-energy-density-matter generation, and ion fast ignition. An accurate understanding of beam transportation behavior in dense matter is crucial for all these applications. Here we report the experimental evidence on one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter, in comparison with the current-widely used models describing individual ion stopping in matter. Supported by particle-in-cell (PIC) simulations, we attribute the enhancement to the strong decelerating electric field approaching 1 GV/m that can be created by the beam-driven return current. This collective effect plays the dominant role in the stopping of laser-accelerated intense proton beams in dense ionized matter. This finding is essential for the optimum design of ion driven fast ignition and inertial confinement fusion.

The ShenGuang-III (SG-III) laser facility was developed by the laser fusion research center (LFRC) for inertial confinement fusion (ICF) studies in China. Over 80 diagnostics have been installed at the SG-III laser facility, including optical diagnostics, x-ray imaging diagnostics, x-ray spectrum diagnostics, fusion product diagnostics and general diagnostics assistant systems, as well as central control and data acquisition systems. Various ICF experiments have also been performed at the SG-III laser facility. The first experiment explored the laser-target coupling process, including investigations of hohlraum radiation flux and laser energy coupling efficiency. The second experiment explored ablation and implosion physics, including shell asymmetry and implosion trajectory. The third experiment explored stagnation, hotspot dynamics and the nuclear phase of the implosion.

A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China. This facility incorporates various diagnostic techniques, including optical, x-ray imaging, x-ray spectrum, and fusion product diagnostics, as well as general diagnostics assistance systems and central control and data acquisition systems. This paper describes recent developments in diagnostics at the facility.

High resolution X-ray diagnosis is a significant method for obtaining ablation-front and trajectory measurements targeting Rayleigh-Taylor (RT)-instability growth in initial confinement fusion (ICF) experiments. In this paper, a novel Kirkpatrick-Baez-type structure, as a kind of essential X-ray micro-imaging apparatus, has been developed that realizes a large field of view (FOV) and images with high resolution and energy response. Zoned multilayer coating technology is applied to the Kirkpatrick-Baez mirrors to transmit two specific quasi-monochromatic light through the same mirror and enables a compact dual-channel structure. This microscope has been assembled in the laboratory and later implemented at the Chinese SG-III laser facility. The characterization results show that this imaging system can achieve a good spatial resolution of 5 µm in a large FOV of 500 µm, while maintaining a strong monochromatic performance with bandwidth of 0.5 keV at 2.5 keV and 4.3 keV respectively.

A recent experiment on the Shenguang III laser facility has applied open-end gold hohlraums with two gas pressures to study the movement of a plasma bubble. Under a laser intensity and width close to those of an ignition main pulse, the bubbles possess radial scales from several hundred to one thousand micrometers. An x-ray framing camera is used to measure the N-band x-ray images generated from the gold bubble plasma at different moments, from which the edge positions of the expanding bubbles are accurately acquired. The experimental results are simulated by an optimized two-dimensional radiation hydrodynamic code. Based on the classical average atom (AA) model, two phenomenological coefficients Cer and Cop are introduced into the code to correct the bubble evolution. Cer artificially redistributes the energies between radiation and matter, and Cop correlatively adjusts the plasma opacity. The bubble movement simulated by the novel phenomenological model agrees better with the measured result than that by the AA model. This work plays a critical role in our code improvements and advances the reliability of the hohlraum design.