文中基于量子阻抗洛伦兹振子（Quantum Impedance Lorentz Oscillator, QILO）模型，研究了含芴二茂铁衍生物的单、双、及三光子吸收特性。首先，理论推导并给出了用有效量子数、电子电量及质量和玻尔半径等微观量表示的该振子四、五阶非线性效应参量的计算参考公式。在此基础上，利用QILO模型，通过拟合取代基为R=NO₂的含芴二茂铁衍生物分子线性吸收光谱，得到了其在400 nm峰值附近的电子跃迁前后的有效量子数，并进一步推算了该分子的双、三光子吸收截面。数值计算结果显示：该化合物分子在793 nm波长附近的双光子吸收截面为 $0.49\times {10}^{-20}\;{\mathrm{c}\mathrm{m}}^{4} \cdot {\mathrm{G}\mathrm{W}}^{-1}$，在1 260 nm和1 314 nm附近的三光子吸收截面分别为 $2.01 \times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6}\cdot{\mathrm{G}\mathrm{W}}^{-2}$、 $1.00\times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6} \cdot {\mathrm{G}\mathrm{W}}^{-2}$，与实验结果均吻合较好。文中结果说明：QILO模型可以较好地描述以NO₂作为取代基的含芴二茂铁衍生物的单、双、及三光子的吸收特性。根据QILO模型的“依据介质的线性吸收光谱可以估算其多光子吸收截面”的特点，该模型或许能为寻找具有大的双、三光子吸收截面的材料提供一种可供参考的理论分析方法，降低研究多光子过程的综合实验成本。

中国散裂中子源二期升级采用超导腔技术方案，其中在165～300 MeV能量段采用648 MHz 6-cell 超导腔模组，每个模组中集成3只6-cell超导腔。超导腔工作在脉冲模式，为了保证超导腔2 K下的频率满足运行要求，每只超导腔需要一套低温调谐器对其频率进行精确调节控制。针对648 MHz 6-cell超导腔的结构和运行特点进行了低温调谐器的设计，采用快慢组合机构补偿超导腔的频率偏移，对调谐器的基本性能和超导腔脉冲模式运行下的动态洛伦兹失谐进行了分析。

中国散裂中子源是中国第一台、世界第四台脉冲型散裂中子源，其已于2020年2月达到100 kW功率的设计指标，运行稳定高效，供束效率位于国际前列。中国散裂中子源二期升级方案中总束流功率将升级到500 kW，其中直线加速器段将采用超导加速腔结构，束流能量由80 MeV提高到300 MeV。其中在80～165 MeV能量段采用324 MHz双spoke超导腔，在165～300 MeV能量段采用648 MHz 6-cell椭球超导腔。采用CST、COMSOL等仿真软件完成324 MHz双spoke超导腔的电磁、机械设计及优化，达到实际运行指标要求。为了提高腔运行的稳定性，在腔的设计中对E_P/E_acc着重进行了优化，使其尽量降低。

The unevenly distributed Lorentz–Gaussian beams are difficult to reproduce in practice, because they require modulation in both amplitude and phase terms. Here, a new linearly polarized Lorentz–Gauss beam modulated by a helical axicon (LGB-HA) is calculated, and the two various experimental generation methods of this beam, Fourier transform method (FTM) and complex-amplitude modulation (CAM) method, are depicted. Compared with the FTM, the CAM method can modulate the phase and amplitude simultaneously by only one reflection-type phase-only liquid crystal spatial light modulator. Both of the methods are coincident with the numerical results. Yet CAM is simpler, efficient, and has a higher degree of conformance through data comparison. In addition, considering some barriers exist in shaping and reappearing the complicated Lorentz–Gauss beam with heterogeneous distribution, the evolution regularities of the beams with different parameters (axial parameter, topological charge, and phase factor) were also implemented.

Chromatic aberration-free meta-devices (e.g., achromatic meta-devices and abnormal chromatic meta-devices) play an essential role in modern science and technology. However, current efforts suffer the issues of low efficiency, narrow operating band, and limited wavefront manipulation capability. We propose a general strategy to design chromatic aberration-free meta-devices with high-efficiency and ultrabroadband properties, which is realized by satisfying the key criteria of desirable phase dispersion and high reflection amplitudes at the target frequency interval. The phase dispersion is tuned successfully based on a multiresonant Lorentz model, and high reflection is guaranteed by the presence of the metallic ground. As proof of the concept, two microwave meta-devices are designed, fabricated, and experimentally characterized. An achromatic meta-mirror is proposed within 8 to 12 GHz, and another abnormal chromatic meta-mirror can tune the reflection angle as a linear function. Both meta-mirrors exhibit very high efficiencies (85% to 94% in the frequency band). Our findings open a door to realize chromatic aberration-free meta-devices with high efficiency and wideband properties and stimulate the realizations of chromatic aberration-free meta-devices with other functionalities or working at higher frequency.