超强激光加速产生的高能质子束源在基础物理研究、材料科学、生物医疗等领域具有广泛应用前景。基于激光聚变研究中心的SILEX-II装置，开展了高对比度飞秒激光驱动纳米刷靶质子加速实验研究。采用等离子体镜技术进一步提升激光对比度，有效降低了预脉冲对纳米刷靶结构的影响。相比于平面靶，采用纳米刷靶质子截止能量提高到1.5倍，质子束产额增加近一个量级，成功验证了超高功率密度下纳米刷靶对激光离子加速的增强效果，并且有效提升了质子束空间分布的均匀性。研究结果为高品质质子束源的产生和应用提供了技术途径。

The impact of radiation reaction and Breit–Wheeler pair production on the acceleration of fully ionized carbon ions driven by an intense linearly polarized laser pulse has been investigated in the ultra-relativistic transparency regime. Against initial expectations, the radiation reaction and pair production at ultra-high laser intensities are found to enhance the energy gained by the ions. The electrons lose most of their transverse momentum, and the additionally produced pair plasma of Breit–Wheeler electrons and positrons co-streams in the forward direction as opposed to the existing electrons streaming at an angle above zero degree. We discuss how these observations could be explained by the changes in the phase velocity of the Buneman instability, which is known to aid ion acceleration in the breakout afterburner regime, by tapping the free energy in the relative electron and ion streams. We present evidence that these non-classical effects can further improve the highest carbon ion energies in this transparency regime.

Characterizing exact energy density distributions for laser-accelerated ion bunches in a medium is challenging due to very high beam intensities and the electro-magnetic pulse emitted in the laser–plasma interaction. Ion-bunch energy acoustic tracing allows for reconstructing the spatial energy density from the ionoacoustic wave generated upon impact in water. We have extended this approach to tracing ionoacoustic modulations of broad energy distributions by introducing thin foils in the water reservoir to shape the acoustic waves at distinct points along the depth–dose curve. Here, we present first simulation studies of this new detector and reconstruction approach, which provides an online read-out of the deposited energy with depth within the centimeter range behind the ion source of state-of-the-art laser–plasma-based accelerators.

The acoustic pulse emitted from the Bragg peak of a laser-accelerated proton bunch focused into water has recently enabled the reconstruction of the bunch energy distribution. By adding three ultrasonic transducers and implementing a fast data analysis of the filtered raw signals, I-BEAT (Ion-Bunch Energy Acoustic Tracing) 3D now provides the mean bunch energy and absolute lateral bunch position in real-time and for individual bunches. Relative changes in energy spread and lateral bunch size can also be monitored. Our experiments at DRACO with proton bunch energies between 10 and 30 MeV reveal sub-MeV and sub-mm resolution. In addition to this 3D bunch information, the signal strength correlates also with the absolute bunch particle number.

We predict the production yield of a medical radioisotope ${}^{67}$ Cu using ${}^{67}$ Zn(n, p) ${}^{67}$ Cu and ${}^{68}$ Zn(n, pn) ${}^{67}$ Cu reactions with fast neutrons provided from laser-driven neutron sources. The neutrons were generated by the p+ ${}^9\mathrm{Be}$ and d+ ${}^9$ Be reactions with high-energy ions accelerated by laser–plasma interaction. We evaluated the yield to be (3.3 $\pm$ 0.5) $\times$ 10 ${}^5$ atoms for ${}^{67}$ Cu, corresponding to a radioactivity of 1.0 $\pm$ 0.2 Bq, for a Zn foil sample with a single laser shot. Using a simulation with this result, we estimated ${}^{67}$ Cu production with a high-frequency laser. The result suggests that it is possible to generate ${}^{67}$ Cu with a radioactivity of 270 MBq using a future laser system with a frequency of 10 Hz and 10,000-s radiation in a hospital.

流动的无支撑液体薄膜在各个领域有着广泛应用。超强激光作用在这样的薄膜上，可产生涵盖太赫兹到伽马射线的高亮度次级辐射及高能的离子，并具有高重频、低成本、可连续工作等显著优势。概述了液体薄膜靶的制备和表征方法，阐明了液体薄膜靶相对于传统靶材的特性和优势，并对其在激光驱动辐射源和激光离子加速中的应用做出了总结和展望。

Single-shot laser-induced damage threshold (LIDT) measurements of multi-type free-standing ultrathin foils were performed in a vacuum environment for 800 nm laser pulses with durations τ ranging from 50 fs to 200 ps. The results show that the laser damage threshold fluences (DTFs) of the ultrathin foils are significantly lower than those of corresponding bulk materials. Wide band gap dielectric targets such as SiN and formvar have larger DTFs than semiconductive and conductive targets by 1–3 orders of magnitude depending on the pulse duration. The damage mechanisms for different types of targets are studied. Based on the measurement, the constrain of the LIDTs on the laser contrast is discussed.