碳气凝胶/聚苯乙烯双介质柱状靶的研制

 介绍了碳气凝胶/聚苯乙烯（CRF/CH）双介质柱状靶的制备方法。使用溶胶-凝胶法和微模具原位成型法制备了直径为820 μm的间苯二酚-甲醛（RF）气凝胶微柱,在氮气保护下进行高温碳化后得到直径为730 μm、密度为250 mg·cm^-3的CRF微柱;采用浸渍提拉法在CRF微柱柱面镀制一层厚度为26 μm 的CH薄膜, 形成CRF/CH双介质结构;采用机械微切割技术制备了长度为1 mm, 内径为730 μm,壁厚为26 μm的CRF/CH双介质柱状靶。实验研究了RF,CRF气凝胶微柱的制备工艺、微观形貌及CRF微柱轴向和径向的密度均匀性,探讨了影响CH薄膜厚度的主要因素,并对CH薄膜的表面形貌和两种材料之间的界面进行了表征。     

ICF流体力学不稳定性实验用柱状激波管的研制

在惯性约束聚变(ICF)实验中,点火靶丸表面(界面)的粗糙度和缺陷所产生的流体力学不稳定性是决定点火成功与否的关键因素之一,设计和研制流体力学不稳定性分解实验用靶是解决该问题的主要技术手段。结合国内外的研究现状和神光-Ⅱ激光装置的特点,设计并研制了一种新型柱状激波管。该靶型由三种介质组成,分别为调制聚苯乙烯(CH)圆片、柱状碳气凝胶(CRF)和CH微套管。调制CH圆片和柱状CRF通过微加工技术装配到CH微套管内,封装后形成柱状激波管。介绍了该靶型的设计原理和详细的制备工艺,并对相应的靶参数进行了测量。结果表明:柱状CRF气凝胶具有较好的成型性,长度、直径和密度分别为1000μm、730μm和250mg·cm-3;CH圆片的厚度和直径分别为15μm和730μm,表面调制图形的周期和峰谷差分别为100μm和4.3μm;实验得到的柱状激波管的轴向和径向最大装配误差分别为2μm和3μm。     

密度渐变多层碳气凝胶靶型的制备

 以间苯二酚-甲醛为原料,结合自制活动式微模具成型工艺制备不同厚度和密度的碳气凝胶薄片,采用密度为10 mg·cm^-3的SiO₂溶胶为“粘合剂”,获得单元薄片厚度在100～580 μm,密度在50～400 mg·cm^-3范围内变化的5层密度渐变碳气凝胶靶型。重点研究了该特殊靶型内部C/SiO₂气凝胶层间界面情况。采用场发射扫描电镜（FESEM）,X射线相衬成像仪等对靶型整体结构及碳气凝胶单元薄片表面和内部微观结构进行了表征。结果表明：胶粘层SiO₂气凝胶厚度约为15 μm,厚度一致,远小于碳气凝胶层厚度且与碳气凝胶薄片的胶粘程度较好,界面平整,靶结构均匀。     

超低密度SiO2气凝胶的制备研究

超低密度的SiO2气凝胶是一种经典的三维网状纳米多孔材料,已经广泛应用于如保温隔热、吸附等多种领域。以四甲氧基硅烷(TMOS)为硅源,采用酸碱两步法,利用乙醇超临界干燥技术制备了超低密度的SiO2气凝胶,分别利用SEM\TEM\BET等表征手段对该气凝胶进行了一系列的研究,发现当其密度为0.6 mg/cm3时,气凝胶拥有最佳的综合性能。该种气凝胶具有超低密度、高比表面积、加工成型性好、制备周期短等优点,有望在激光惯性约束聚变实验中作为冷冻靶发挥巨大的作用。     

碳气凝胶薄片的制备及表面密度致密层去除工艺

研究了不同密度和厚度的碳气凝胶薄片的制备及其表面致密层去除工艺。在以间苯二酚、甲醛为原料制备有机及碳气凝胶块体材料的基础上,结合自制活动式微模具成型工艺,制备了厚度在80~350 μm,密度在50~600 mg·cm-3范围内变化的碳气凝胶薄片。采用场发射扫描电镜、X射线相衬成像和表面轮廓仪-台阶仪等手段对其表面和内部微观结构进行了表征。测试结果表明,碳气凝胶薄片与块体的内部结构相同,但薄片表面存在一层和内部结构截然不同的致密层。采用不同粗糙程度的材料对薄片进行了表面微处理,成功去除该致密“皮”层。     

用于ICF实验的掺溴聚苯乙烯平面调制箔靶

以掺溴聚苯乙烯平面调制箔靶的制备为主，介绍通过激光干涉法结合图形转移工艺获得具有正弦起伏图形的掺溴聚苯乙烯平面调制箔靶的工艺．对表面调制起伏图形的精确转移进行研究，以ＳＥＭ和台阶仪监控图形转移过程，控制耦合在调制图形上的表面粗糙度．     

碳气凝胶薄片的制备及表面密度致密层去除工艺

 研究了不同密度和厚度的碳气凝胶薄片的制备及其表面致密层去除工艺。在以间苯二酚、甲醛为原料制备有机及碳气凝胶块体材料的基础上,结合自制活动式微模具成型工艺,制备了厚度在80~350 μm,密度在50~600 mg·cm^-3范围内变化的碳气凝胶薄片。采用场发射扫描电镜、X射线相衬成像和表面轮廓仪-台阶仪等手段对其表面和内部微观结构进行了表征。测试结果表明,碳气凝胶薄片与块体的内部结构相同,但薄片表面存在一层和内部结构截然不同的致密层。采用不同粗糙程度的材料对薄片进行了表面微处理,成功去除该致密“皮”层。     

低密度Cu掺杂SiO_2复合气凝胶的制备及表征

分别以正硅酸甲酯、醋酸铜为硅源和铜源,通过溶胶凝胶法及CO2超临界干燥技术制备了一系列Cu掺杂SiO2复合气凝胶。采用红外谱仪(FTIR)、扫描电镜(SEM)、X射线能谱仪(EDS)、比表面积和孔隙度分析仪(BET)、动态热机械分析仪(DMA)对样品进行了表征。结果表明随着铜含量的增加,复合气凝胶密度增加,比表面积降低,平均孔径增加,实际掺杂比与理论掺杂比对应增加。该复合气凝胶具有三维网状结构,密度低(40mg/cm3),比表面积高(390m2/g),成型性较好,有望应用于惯性约束聚变(ICF)实验。     

掺溴聚苯乙烯平面调制箔靶的制备及测量

 平面调制靶是ICF分解实验中的重要用靶。介绍了在过去工作的基础上掺溴聚苯乙烯平面调制箔靶的制备工艺,研究旋转涂覆和流延工艺对靶的表面起伏图形转移的影响,采用SEM观察薄膜表面起伏图形的形貌,对掺杂溴的含量进行测量和控制,以台阶仪测量靶的表面粗糙度。     

超低密度SiO2气凝胶的制备及成型研究

 以正硅酸乙酯(TEOS)为硅源，采用酸碱二步催化溶胶-凝胶法，结合超临界干燥技术制备了超低密度SiO₂气凝胶,最低密度为3.4 mg/cm³；进一步结合成型工艺，在解决了模具设计和脱模技术后制备了具有不同密度的柱状和微型套筒样品，密度10～50 mg/cm³。研究了水、催化剂、稀释剂对二步溶胶-凝胶过程的影响，获得了制备低密度SiO₂气凝胶的最佳条件。利用扫描电镜、孔径分布及比表面积测试仪等对SiO₂气凝胶微结构进行了研究。结果表明，获得的超低密度SiO₂气凝胶具有较好的纳米网络，平均孔径18.9 nm，还具有高比表面积898 9 m²/g。     

锌基复合气凝胶的微观结构

以ZnCl2为前躯物,不同相对分子质量的聚丙烯酸为模版剂,环氧丙烷作为催化剂,超临界干燥成功制得了锌基复合气凝胶。运用场发射扫描电镜、高分辨透射电子显微镜和N2等温吸附测试对气凝胶的微观结构进行了表征。结果表明,制备的锌基复合气凝胶呈现三维网络状结构,其三维结构是由大量微小颗粒组成,颗粒的粒径为nm量级,为介孔材料。选用相对分子质量为1800的聚丙烯酸作为模版剂制备的气凝胶的微观结构最好,无明显的塌陷和团聚现象,其比表面积为236 m2/g,平均孔径分布在11 nm左右,总的孔体积为0.179 cm3/g。     

Backscattering of Relativistic Electrons Incident on a Planar Foil at a Small Angle to Its Surface

Photographs of cross sections of an electron beam backscattered from a thin tungsten target have been obtained on a dosimetric film. The procession of images makes it possible to obtain the spatial distribution of backscattered particles. The angles of back reflection θ_br of electron beams from foils have been measured. A 7.4-MeV microtron has been used as a source of electrons. The experiments have been performed with a tungsten foil 386 mg/cm² (200 μm) thick and a tantalum foil 1328 mg/cm² (800 μm) thick. Particles have been injected at an angle of α = 10° to the foil surface. The Monte Carlo simulation of the scattering of relativistic electrons incident on a planar target at small angles to its surface has been performed. The spatial and energy distributions of backscattered particle fluxes both transmitted through the target and reflected from it have been calculated. The dependences of fluxes on the direction of injection of particles and on the material and thickness of the target have been considered.     

Particular features of the transmission of laser radiation with wavelength 0.438 µm and intensity (3–7)·1014 W/cm2 through an undercritical plasma from polymer aerogels

The velocities of energy transport in an undercritical plasma of polymer aerogel with and without copper nanoparticles were measured. Transmission of the laser light through targets of different thicknesses such as submicron three-dimensional polymer networks with densities below the critical value (0.13–0.52 N _cr) for a wavelength of 0.438 μm and intensity of (3–7)·10¹⁴ W/cm² at a half-height pulse duration of 0.32 ns was studied. The transfer of a heating laser radiation was registered on the rear side of the target. It ranged from a level of ∼0.5% for the thickness of a low-density layer of 400 μm and density of 9 mg/cm³ (mass per unit square of 0.36 mg/cm²) up to 50–60% for a thickness of 100 μm and density of 2.25 mg/cm³ (mass per unit square of 0.02 mg/cm²). The time dependences of the optical emission from the rear side of the targets were measured. They appear to be indicative of the plasma dynamics in two-layer targets (polymer foam on Al foil) and enable the estimation of the absorption depth for the laser light in an undercritical plasma. __________ Translated from Preprint No. 8 of the P. N. Lebedev Physical Institute, Moscow (2007).     

Nuclear fusion induced by a super-intense ultrashort laser pulse in a deuterated glass aerogel

A SiO₂ aerogel with absorbed deuterium is proposed as a target for the fusion reaction d + d → He³ + n induced by a superintense ultrashort laser pulse. The multiple inner ionization of oxygen and silicon atoms in the aerogel skeleton occurs in the superintense laser field. All the formed free electrons are heated and removed from the aerogel skeleton by the laser field at the front edge of the laser pulse. The subsequent Coulomb explosion of the deuterated charged aerogel skeleton propels the deuterium ions up to kinetic energies of ten keV and higher. The neutron yield is estimated at up to 10⁵ neutrons per laser pulse for ～200–500 ps if the peak intensity is 10¹⁸ W/cm² and the pulse duration is 35 fs.     

Studies on the performances of silica aerogel electrodes for the application of supercapacitor

Silica aerogel (SiO₂ aerogel) was prepared by sol–gel method from tetraethyl orthosilicate hydrolyzation and has been characterized by scanning electron microscopy and N₂ adsorption for its surface structure, surface area, and pore-size distribution. Constant current charge–discharge technique, cyclic voltammetry, and electrochemical impedance spectrum were employed for its specific capacitance and equivalent series resistance. The results showed that the maximum specific capacitance of SiO₂ aerogel electrode in 1 M Et₄NBF₄/PC electrolyte was 62.5 F g⁻¹. In addition, the SiO₂ aerogel capacitor exhibits excellent long-term stability with no significant degradation after 500 charging and discharging cycles. Therefore, the application of high surface area SiO₂ aerogel as electrodes in supercapacitor devices is promising.     

用SCLC法研究低k多孔SiO2:F薄膜的隙态密度

用溶胶-凝胶法制备了低k多孔SiO₂:F薄膜，用空间电荷限制电流法(SCLC)研究了多孔SiO₂:F薄膜中的隙态密度以及掺F量对隙态密度的影响，得到了平衡费米能级附近的隙态密度约为7×10¹⁵cm^-3·eV^-1，以及带隙中隙态随能量的分布. 并对造成隙态的主要原因也进行了讨论.