采用简单、绿色、低成本的方法合成石墨烯量子点（GQDs）一直是研究者们不断追求和探究的热点。本文首先采用简单、低成本的激光诱导聚二甲基硅氧烷（PDMS）方法成功制备出有缺陷的少层石墨烯, 然后再以所制备的石墨烯为碳源, 采用一步水热法成功制备出了分散性良好、横向平均尺寸约为6.67 nm、发稳定蓝色荧光的GQDs溶液。分别采用透射电镜（TEM）、拉曼光谱、紫外吸收光谱和荧光光谱对GQDs的形貌和荧光特性进行了表征。以硫酸奎宁为标准参考物, 计算所得GQDs的荧光量子产率约为6.3%。本研究提出的制备GQDs的方法具有简单、低成本、低污染的优势, 为石墨烯量子点的制备提供了一种新途径、新参考, 也为石墨烯量子点大规模商业化制备提供了潜力。

椭圆弯晶谱仪具有测谱宽度大, 能谱分辨力高等特点, 并在"神光II"激光惯性约束聚变实验研究中得到了很好的应用。利用X射线衍射仪铜(Cu)靶 X射线管作为X射线线光源, 选取合适厚度滤片, 抑制Cu-Kβ 线及韧致辐射, 测量了Cu-K α能点处二氧化硅石英椭圆弯晶的积分衍射效率和摆动曲线半高全宽, 并开展了针对上述两个重要参数随晶体弯曲曲率半径改变的测试验证, 预估了能谱分辨力。结果表明, 椭圆弯晶的积分衍射效率和摆动曲线半高全宽对晶体弯曲半径改变敏感, 通过提高晶体弯曲度可增强晶体"镶嵌"效果。该结果可为下一步优化设计多用途性椭圆弯晶谱仪, 以及完善X射线光谱定量化测量提供了数据支撑。

The coupling efficiency of short-pulse ignition laser energy to hot-spot internal energy directly affects the feasibility of fast ignition. Experimental characterization of the hot spot has attracted much attention. Among temperature, density and neutron yield of fast ignition experiments, the temperature of the hot spot has few available diagnostic methods. Multispectral X-ray imaging of hot-spot continuum emission is expected to give the time evolution of the electron temperature distribution. This article describes electron temperature determination from multispectral imaging, a dual-channel X-ray Kirkpatrick-Baez (KB) microscope designed for two-spectral imaging, and the experimental results of hot-core multispectral imaging of an imploded cone-shell target at the SG-II laser facility.

The X-ray spectrometer used in high-energy-density plasma experiments generally requires both broad X-ray energy coverage and high temporal, spatial, and spectral resolutions for overcoming the difficulties imposed by the X-ray background, debris, and mechanical shocks. By using an elliptical crystal together with a streak camera, we resolve this issue at the SG-II laser facility. The carefully designed elliptical crystal has a broad spectral coverage with high resolution, strong rejection of the diffuse and/or fluorescent background radiation, and negligible source broadening for extended sources. The spectra that are Bragg reflected (23°<θ<38°) from the crystal are focused onto a streak camera slit 18 mm long and about 80 μm wide, to obtain a time-resolved spectrum. With experimental measurements, we demonstrate that the quartz(1011) elliptical analyzer at the SG-II laser facility has a single-shot spectral range of (4.64–6.45) keV, a typical spectral resolution of E/DE = 560, and an enhanced focusing power in the spectral dimension. For titanium (Ti) data, the lines of interest show a distribution as a function of time and the temporal variations of the He-a and Li-like Ti satellite lines and their spatial profiles show intensity peak red shifts. The spectrometer sensitivity is illustrated with a temporal resolution of better than 25 ps, which satisfies the near-term requirements of high-energy-density physics experiments.

This paper explores the parameter measurement in laser produced plasma by X-ray line profile spectrscopy. The experiment was conducted on the SG-II laser facility. A 0.35 μm laser beam was focused on a solid chlorine (Cl) target in a vacuum chamber to produce a laser chlorine plasma and the high resolution X-ray elliptical bent crystal spectrograph was used to obtain the X-ray fine structure energy spectrum of the chlorine plasma radiation. The line integrated intensity ratio between H-like Cl (1s-3p) (Lyman-) and He-like Cl (1s2-1s3p) (He-) transitions was used for calculation of the electron temperature. By assuming optically thin, the Lyman-stark broadened profile was utilized to measure the electron density. Obtained experimental results show that the volume averaged electron temperature of Te is about 450 eV and the electron density of Ne is approximately 7.5×1022 cm-3. In addition, the line Full Width at Half Maximum (FWHM) was analyzed. The uncertainty in Ne due to uncertainties in the temperature and the assumed background level was also simply discussed and it is estimated to be within 25%. As a result, the experimental spectroscopic method may become a reference for diagnosing future higher-compression implosions.

开展了利用X射线特征谱轮廓诊断激光等离子体状态参数的研究。在"神光II"激光装置上, 将 0.35 μm频谱激光束聚焦于真空室内固体氯(Cl)元素靶上产生激光氯等离子体, 利用高分辨X射线椭圆弯晶谱仪获取高能谱分辨激光氯等离子体辐射的X射线精细结构能谱。用类氢(1s-3p)和类氦(1s2-1s3p)氯离子能级跃迁光谱线的光强度比率计算了激光等离子体的电子温度; 然后在假定光性为薄的情况下, 利用X射线谱线Lyman-线形轮廓的Stark效应所产生的谱线展宽测量了等离子体的电子密度。实验获得的激光等离子体日冕区内体平均电子温度约为450 eV, 电子密度约为7.5×1022 cm-3。文中还简单分析了能谱线的半高全宽度(FWHM)值以及诊断过程引入的诊断误差, 初步预估诊断误差可控制在25%以内。该项工作为X射线特征谱轮廓法进一步应用于激光聚变靶丸压缩度精度测量等工作提供了参考。

An experiment with thin titanium foils irradiated by two pulses delayed in time is conducted on the Shenguang-II laser facility. A prepulse induces an underdense plasma, 2-ns later a main pulse (λ_L = 0.35 μm, E_L = 120 J, τ_L = 100 ps) is injected into the underdense plasma and produces strong line emission from the titanium K shell (i.e., He_α at 4.7 keV). Data show that the intensity of 4.7-keV X-ray emission with the prepulse is approximately twice more than without the prepulse, and can be used as a backlighting source satisfying the diagnostic requirements for dense plasma probing. Highquality plasma images are obtained with the backlighting 4.7-keV X-rays in a Rayleigh–Taylor hydrodynamic instability experiment.

Several experiments are performed on the ShenGuang-II laser facility to investigate an x-ray source and test radiography concepts. X-ray lines emitted from laser-produced plasmas are the most practical means of generating these high intensity sources. By using a time-integrated space-resolved keV spectroscope and pinhole camera, potential helium-like titanium Kα x-ray backlighting (radiography) line source is studied as a function of laser wavelength, ratio of pre-pulse intensity to main pulse intensity, and laser intensity (from 7.25 to ~ 11.3×10¹⁵ W/cm²). One-dimensional radiography using a grid consisting of 5 μm Au wires on 16 μm period and the pinhole-assisted point projection is tested. The measurements show that the size of the helium-like titanium Kα source from a simple foil target is larger than 100 μm, and relative x-ray line emission conversion efficiency ξ_x from the incident laser light energy to heliumlike titanium K-shell spectrum increases significantly with pre-pulse intensity increasing, increases rapidly with laser wavelength decreasing, and increases moderately with main laser intensity increasing. It is also found that a gold gird foils can reach an imaging resolution better than 5-μm featured with high contrast. It is further demonstrated that the pinhole-assisted point projection at such a level will be a novel two-dimensional imaging diagnostic technique for inertial confinement fusion experiments.

讨论了椭圆弯晶谱仪的波长分辨能力。在假设谱线的固有宽度可以忽略的情况下，对两种实际影响椭圆弯晶谱仪波长分辨能力的主要因素，即光源空间尺寸和非理想椭圆分光晶面进行了分析。分别对上述两种情况进行了数学建模和数值模拟仿真。定量地分析了非理想椭圆晶面和光源空间尺寸对椭圆弯晶X射线谱仪波长分辨本领的影响程度，并给出了出射狭缝宽度与椭圆弯晶谱仪波长判读加宽的关系。从理论上论证了光源空间尺寸在限制谱仪的波长分辨能力方面仍然起关键主导作用；结合椭圆分光晶体的结构参数，合理地选择出射狭缝宽度，可使谱仪达到足够好的光谱分辨率和信噪比。用搭建的实验平台进行了实验测试，结果表明，当出射狭缝宽度(2δ)为10 mm时，实测的谱线半高全宽(Δλ)为3.1×10-3 nm；2δ为4 mm时，Δλ为2.3×10-4 nm，实测结果佐证了仿真结果的正确性。

描述了椭圆型晶体谱仪配X射线CCD相机的X射线谱测量系统(EBCS-XCCD),研究了CCD相机记录信号的解谱处理方法,推出了对实测原始谱曲线辨认或标识值的计算公式及激光等离子体辐射X射线在某一波长光谱强度的公式,使之应用在激光打靶产生的等离子体源辐射X射线谱的回推,辨认出了激光等离子体X射线源能谱,并与文献[1]的结果进行了比较,结果基本一致。测试结果证实了解谱方法的可行性,表明X射线CCD相机适用于椭圆型晶体谱仪的光谱测量记录。在已知晶体的积分反射率、滤片透射率和CCD探测效率的条件下,可以获得X射线源光谱强度,为下一步诊断激光等离子体的电子温度和离子密度的空间分布轮廓和进一步细化X射线激光研究奠定了基础。