This work presents a brief introduction on three kinds of newly developed $\text{Nd}^{3+}$-doped laser glasses in Shanghai Institute of Optics and Fine Mechanics (SIOM), China. Two $\text{Nd}^{3+}$-doped phosphate glasses with lower thermal expansion coefficient and thermal shock resistance 4 times higher than that of N31 glass are developed for laser processing. Nd:Silicate and Nd:Aluminate glasses with peak emission wavelength at 1061 and 1065 nm, effective emission bandwidth of 34 and 50 nm, respectively, are developed for Exawatt-class laser system application. Fluorophosphate glasses with low nonlinear refractive index ($n_{2}=0.6{-}0.86$) and long fluorescence lifetime ($430{-}510~\unicode[STIX]{x03BC}\text{s}$) are investigated for the purpose of decreasing B integral in high-power laser system. The properties of all these glasses are presented and compared with those of commercial neodymium laser glasses.

The Laboratory for Intense Lasers (L2I) is a research centre in optics and lasers dedicated to experimental research in high intensity laser science and technology and laser plasma interaction. Currently the laboratory is undergoing an upgrade with the goal of increasing the versatility of the laser systems available to the users, as well as increasing the pulse repetition rate. In this paper we review the current status of the laser research and development programme of this facility, namely the upgraded capability and the recent progress towards the installation of an ultrashort, diode-pumped OPCPA laser system.

Optical vortices are structures of the electromagnetic field with a spiral phase ramp about a point-phase singularity, carrying orbital angular momentum (OAM). Recently, OAM has been imprinted to short-wavelength radiation through high-order harmonic generation (HHG), leading to the emission of attosecond twisted beams in the extreme-ultraviolet (XUV) regime. We explore the details of the mapping of the driving vortex to its harmonic spectrum. In particular, we show that the geometry of the harmonic vortices is convoluted, arising from the superposition of the contribution from the short and long quantum paths responsible of HHG. Finally, we show how to take advantage of transverse phase-matching to select twisted attosecond beams with different spatiotemporal properties.

The ultrafast charge dynamics following the interaction of an ultra-intense laser pulse with a foil target leads to the launch of an ultra-short, intense electromagnetic (EM) pulse along a wire connected to the target. Due to the strong electric field (of the order of $\text{GV m}^{-1}$) associated to such laser-driven EM pulses, these can be exploited in a travelling-wave helical geometry for controlling and optimizing the parameters of laser accelerated proton beams. The propagation of the EM pulse along a helical path was studied by employing a proton probing technique. The pulse-carrying coil was probed along two orthogonal directions, transverse and parallel to the coil axis. The temporal profile of the pulse obtained from the transverse probing of the coil is in agreement with the previous measurements obtained in a planar geometry. The data obtained from the longitudinal probing of the coil shows a clear evidence of an energy dependent reduction of the proton beam divergence, which underpins the mechanism behind selective guiding of laser-driven ions by the helical coil targets.

As the basic conditions for laser inertial confinement fusion (ICF) research, the targets are required to be well specified and elaborately fabricated. Because of the characteristics of the targets, the research and fabrication process is a systematically tough task, which needs fundamental and deep insights into film deposition, mechanical machining, precise measurement and assembly, etc. As a result, knowledge of material science, physics, mechanical as well as electronics is a necessity for target researchers. In this paper, we give introductions to the state of art on target fabrication for ICF research at Research Center of Laser Fusion (RCLF) in China.

A unique approach for permeation filling of nonpermeable inertial confinement fusion target capsules with deuterium–tritium (DT) is presented. This process uses a permeable capsule coupled into the final target capsule with a 0.03-mm-diameter fill tube. Leak free permeation filling of glow-discharge polymerization (GDP) targets using this method have been successfully demonstrated, as well as ice layering of the target, yielding an inner ice surface roughness of 1-$\unicode[STIX]{x03BC}$m rms (root mean square). Finally, the measured DT ice-thickness profile for this experiment was used to validate a thermal model’s prediction of the same thickness profile.

This paper provides a review on sample injectors which are provided at SPring-8 Angstrom Compact free electron LAser (SACLA) for conducting serial measurement in a ‘diffract-before-destroy’ scheme using an x-ray free electron laser (XFEL). Versatile experimental platforms at SACLA are able to accept various types of injectors, among which liquid-jet, droplet and viscous carrier injectors are frequently utilized. These injectors produce different forms of fluid targets such as a liquid filament with a diameter in the order of micrometer, micro-droplet synchronized to XFEL pulses, and slowly flowing column of highly viscous fluid with a rate below $1~\unicode[STIX]{x03BC}\text{L}~\text{min}^{-1}$. Characteristics and applications of the injectors are described.

Modern chirped pulse amplification laser systems with continuously improving controllability and increasing power are about to reach intensities of up to $10^{22}~\text{W}~\text{cm}^{-2}$ and have proven their potential to accelerate ions out of plasma to several tens percent of the speed of light. For enabling application, one important step is to increase the repetition rate at which ion bunches are at the disposal. In particular, techniques used so far for thin foil target production can require several days of preparing reasonable amounts for a single campaign. In this paper we describe the reasonably droplet method which we have tested and improved so that the emerging foils with thicknesses of a few nanometres up to micrometre can be used as targets for laser ion acceleration. Their quality and performance can compete with so far employed techniques thereby enabling the production of hundreds of targets per day.

The designs of inertial confinement fusion (ICF) targets, which field on ShenGuang III, are becoming more complex and more stringent in terms of assembly precision. A key specification of these targets is the spatial angle alignment accuracy. To meet these needs, we present a new spatial angle assembly method, using target part’s 3D model-based dual orthogonal camera vision, which is better suited for the flexible automation of target assembly processes. The two-hands structure micromanipulate system and dual orthogonal structure visual feedback system were investigated by considering the kinematics, spatial angle measuring, and motion control in an integrated way. In this paper, we discuss the measurement accuracy of spatial angle assembly method, which compared the real-time image acquisition with the redrawing 2D projection. The result shows that the assembly method proposed is very effective and meets the requirements of angle assembly accuracy, which is less than $1^{\circ }$. Also, this work is expected to contribute greatly to the advancement of other target microassembly equipments.

The Be-based materials with many particular properties lead to an important research subject. The investigation progresses in the fabrication technologies are introduced here, including main three kinds of Be-based materials, such as Be–Cu capsule, $\text{Be}_{2}\text{C}$ ablator and high-purity Be material. Compared with the pioneer workgroup on Be-based materials, the differences in Be–Cu target fabrication were described, and a grain refinement technique by an active hydrogen reaction for Be coating was proposed uniquely. $\text{Be}_{2}\text{C}$ coatings were first prepared by the DC reactive magnetron sputtering with a high deposition rate $({\sim}300~\text{nm}/\text{h})$. Pure polycrystalline $\text{Be}_{2}\text{C}$ films with uniform microstructures, smooth surface, high density $({\sim}2.2~\text{g}\cdot \text{cm}^{3})$ and good optical transparency were fabricated. In addition, the high-purity Be materials with metal impurities in a ppm magnitude were fabricated by the pyrolysis of organometallic Be.

In inertial fusion energy (IFE) research, a considerable attention has recently been focused on the issue of large target fabrication for MJ-class laser facilities. The ignition and high-gain target designs require a condensed uniform layer of hydrogen fuel on the inside of a spherical shell. In this report, we discuss the current status and further trends in the area of developing the layering techniques intended to produce ignition, and layering techniques proposed to high repetition rate and mass production of IFE targets.

We report on a target system supporting automated positioning of nano-targets with a precision resolution of $4~\unicode[STIX]{x03BC}\text{m}$ in three dimensions. It relies on a confocal distance sensor and a microscope. The system has been commissioned to position nanometer targets with 1 Hz repetition rate. Integrating our prototype into the table-top ATLAS 300 TW-laser system at the Laboratory for Extreme Photonics in Garching, we demonstrate the operation of a 0.5 Hz laser-driven proton source with a shot-to-shot variation of the maximum energy about 27% for a level of confidence of 0.95. The reason of laser shooting experiments operated at 0.5 Hz rather than 1 Hz is because the synchronization between the nano-foil target positioning system and the laser trigger needs to improve.

Ultrashort laser pulses are used to create surface structures on thin ($25~\unicode[STIX]{x03BC}\text{m}$) silicon (Si) wafers. Scanning the wafer with a galvanometric mirror system creates large homogeneously structured areas. The variety of structure shapes that can be generated with this method is exemplified by the analysis of shape, height and distance of structures created in the ambient media air and isopropanol. A study of the correlation between structure height and remaining wafer thickness is presented. The comparatively easy manufacturing technique and the structure variety that allows for custom-tailored targets show great potential for high repetition rate ion acceleration experiments.

The improved laser-to-pedestal contrast ratio enabled by current high-power laser pulse cleaning techniques allows the fine features of the target survive before the main laser pulse arrives. We propose to introduce the nano-fabrication technologies into laser–plasma interaction to explore the novel effects of micro-structures. We found out that not only laser-driven particle sources but also the laser pulse itself can be manipulated by specifically designed micro-cylinder and -tube targets, respectively. The proposal was supported by full-3D particle-in-cell simulations and successful proof-of-principle experiments for the first time. We believe this would open a way to manipulate relativistic laser–plasma interaction at the micro-size level.

Targets have been developed to measure supersonic radiation transport in aerogel foams using absorption spectroscopy. The target consists of an aerogel foam uniformly doped with either titanium or scandium inserted into an undoped aerogel foam package. This creates a localized doped foam region to provide spatial resolution for the measurement. Development and characterization of the foams is a key challenge in addition to machining and assembling the two foams so they mate without gaps. The foam package is inserted into a beryllium sleeve and mounted on a gold hohlraum. The target is mounted to a holder created using additive manufacturing and mounted on a stalk. The manufacturing of the components, along with assembly and metrology of the target are described here.

Muons produced by a short pulse laser can serve as a new type of muon source having potential advantages of high intensity, small source emittance, short pulse duration and low cost. To validate it in experiments, a suitable muon diagnostics system is needed since high muon flux generated by a short pulse laser shot is always accompanied by high radiation background, which is quite different from cases in general muon researches. A detection system is proposed to distinguish muon signals from radiation background by measuring the muon lifetime. It is based on the scintillator detector with water and lead shields, in which water is used to adjust energies of muons stopped in the scintillator and lead to against radiation background. A Geant4 simulation on the performance of the detection system shows that efficiency up to 52% could be arrived for low-energy muons around 200 MeV and this efficiency decreases to 14% for high-energy muons above 1000 MeV. The simulation also shows that the muon lifetime can be derived properly by measuring attenuation of the scintilla light of electrons from muon decays inside the scintillator detector.

A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.

Proton radiography is a key diagnostics to measure and image the electric/magnetic field in laser-produced plasmas. A thin solid target is irradiated with an intense laser pulse to produce a proton beam. The accelerated proton can achieve higher energy with thinner target. In order to produce an extremely thin target, we have developed a large-area suspended graphene as a laser target for energetic ion sources. We describe the manufacturing process of the suspended graphene, and show the results of quality evaluations.

Inertial confinement fusion targets are complex systems designed to allow fine control of temperature and pressure for making precise spherical ice layers of hydrogen isotopes at cryogenic temperatures. We discuss the various technical considerations for a maximum leak rate based on heat load considerations. This maximum flow rate turns out to be $5\times 10^{-6}$ standard cc per second, which can be caused by an orifice less than half a micron in diameter. This makes the identification of the location and resolution of the leak a significant challenge. To illustrate this, we showcase one example of a peculiar failure mode that appeared suddenly but persisted whereby target production yield was severely lowered. Identification of the leak source and the root cause requires very careful analysis of multiple thermomechanical aspects to ensure that the end solution is indeed the right remedy and is robust.

In indirect drive, reducing peak intensity of a single beam and controlling overlap of multi-beams are two opposite requirements for laser focal spot design. In this paper, an improved laser spot design technique for indirect drive built upon the geometric structures of laser propagation into hohlraum has been introduced. The proposed technique is able to generate appropriate continuous phase plate (CPP) producing a special shaped spot that can balance the opposite requirements. The corresponding CPP does not bring difficulties to the design and fabrication. Phase aberrations are more sensitive to the special shaped spot; however, it can be tolerable for the current beam control level.