原子发射光谱法研究SCB放电特性

半导体桥(SCB)通过桥膜放电进行含能材料的点火,具有低点火能量、高安全性以及能与数字逻辑电路组合等优点.文章利用原子发射光谱技术研究了其放电特性.首先用Cu原子谱线510.5和521.8 nm进行温度测垦,用Si原子谱线390.5 nm和Si离子线413.0 nm进行电子密度测量,同时获得SCB放电温度和电子密度随时间分布的测量结果.在放电电压为20 V,充电电容为47 μF条件下,1.0 Ω的SCB放电温度分布在2 500～4 300 K之间,电子密度约为1016 cm-3左右.然后根据光谱诊断结果,结合等离子体成立的空间尺度和时问尺度条件,判断两种规格的SCB的放电行为是否产生等离子体.该研究结果为SCB桥体的设计以及点火方式的控制提供了理论依据.也为瞬态小尺寸等离子体的判断和诊断提供了一种参考方法.     

炸药爆轰瞬态温度的光谱法测定

在双谱线原子发射光谱测温原理的基础上,设计了对炸药爆轰的瞬态温度进行实时测量的光纤光谱测试系统,利用光学纤维将炸药爆轰的光谱信号传入测光系统,用多通道数据采集器处理数据,系统的时间分辨率可高达0.1μs,所选择的两条谱线的波长分别为CuI 510.5和CuI 521.8nm,为炸药爆温的测量提供了一种简单有效的方法。利用该测温系统,通过对炸药爆轰光谱的测量,获得了实时瞬态爆轰温度-时间分布曲线。     

单针与针-板喷枪放电特性的比较研究

通过光学与电学测量,对大气压氩气中运行的单针喷枪和针-板喷枪的放电特性进行了研究。结果表明两种喷枪产生等离子体的长度和截面积都随着外加电压峰值(U_p)的增大而增大。相同U_p下针-板喷枪等离子体截面积比单针喷枪大。相同U_p下针-板喷枪放电的外加电压比单针喷枪的低。通过采集两种喷枪放电的发射光谱,对其等离子体的电子温度和振动温度进行了比较。结果发现两种喷枪的电子温度和振动温度均随着U_p的增大而增大,且相同电压下针-板喷枪的温度高于单针喷枪。研究结果对大气压等离子体喷枪的工业应用具有重要价值。     

大气压等离子体射流中振转温度的发射光谱研究

通过发射光谱对大气压氦等离子体射流三个不同位置进行测量, 并采用光谱拟合获得氮气分子振转温度的方法, 研究了放电电压和气体流量以及离喷口的距离对射流的温度和化学活性的影响。发现大气压等离子体射流的气体温度和振动温度均随着放电电压增加而升高, 随着气体流量的增大而降低, 随着离喷口距离的增加而降低并逐步趋于稳定。通过对等离子体射流中振动温度的变化趋势并结合活性成分氧原子光谱强度的变化证实了等离子体射流的活性亦随着气体流量及离喷口距离的增大而降低, 随着放电电压增加而升高的结论。     

激光诱导钛产生等离子体的光谱分析及电子温度的测量

用Nd∶YAG激光器产生的1.06μm、10ns的脉冲激光激发钛靶,用光学多通道分析仪(OMAII)测量了钛等离子体的时间分辨发射光谱,记录并分析了在40ns~200ns延迟范围内438~448nm波段的钛等离子光谱,用一组钛原子谱线的相对强度计算了不同延迟时间下等离子体电子温度。     

较大体积的大气压空气介质阻挡放电特性研究

利用三电极介质阻挡放电装置, 在主放电区产生了较大体积的大气压空气均匀放电. 利用光学与电学方法, 对主放电特性进行了研究, 发现随驱动功率的不同, 主放电存在等离子体羽和等离子体柱两种模式, 等离子体羽的击穿电压随外加电压峰值的增加而减小. 利用光电倍增管对两种放电模式进行了空间分辨测量, 发现等离子体羽是以发光光层的形式传播, 而等离子体柱是连续放电. 通过采集两种放电的发射光谱, 对其振动温度和转动温度进行了测量. 发现两种放电模式的振转温度均随着U_p的增大而降低. 关键词： 介质阻挡放电 等离子体羽 等离子体柱 发射光谱     

分子发射光谱法测量微波等离子体气体温度

通过OH自由基A2Σ+→X2Π_r电子带系分子发射光谱测温法,实现了对氩气、氮气、空气三种大气压微波等离子体气体温度的测量。探究了不同微波功率、不同气体流量下气体温度的变化规律,测量了氮气、空气微波等离子体羽流的轴向温度分布。实验结果表明,不同工作条件下微波等离子体核心温度普遍超过2 000 K,空气微波等离子体可超过6 000 K;同样工作条件下三种微波等离子体气体温度满足：T_Ar<T_N2<T_Air;气体温度总体上随微波功率增加而小幅增加,随气体流量下降而小幅降低;氮气与空气等离子体羽流温度沿轴向迅速降低。为验证分子发射光谱测温法的准确性,以热电偶测温作为比对,对温度较低的介质阻挡放电氩气等离子体进行了温度测量,实验表明,分子发射光谱法与热电偶所测结果十分接近。     

等离子体激发和辐射温度瞬态光谱测试方法

对等离子体温度的测量能间接诊断瞬态物理场的瞬时温度变化.使用望远光学系统对准等离子体并收集其光谱.光栅分光系统高精度地(△λ<0.1 nm)分离提取出测最所需的等离子体四通道特征光谱信号.光纤将光谱信号导入高灵敏度、快速响应的光电倍增管(PMTs,采集时间小于1 μs),达到瞬态测试的要求.用四通道数据拟合Boltzmann直线提高了计算激发温度的精度(优于2%),同时从黑体辐射理论推导出等离子体辐射温度的计算模型.只需用一次测量得到的光强就可以同时得到等离子体的激发温度和辐射温度.利用标准温度灯对系统的光谱响应系数进行了标定,通过实验表明系统测温的精度优于3%.     

用发射光谱法测量氮气直流辉光放电的转动温度

本文报道了氮气气压分别为10和20Pa时，对直流辉光放电的发射光谱进行测量和分析的结果。选择的研究对象为N2放电中形成的N2^ B^2∑u^ →X^2∑g^ 跃迁的Δv=v′-v″=0谱带系中v′=0→v″=0谱带的R支。在阴极背面辉光区、阴极鞘层区、正柱区以及阳极辉光区中分别选择一点进行了转动分辨的发射光谱的测量。利用自己编写的光谱拟合程序，获得了相应的实验条件下N2^ 的转动温度，给出了转动温度随放电电压的变化趋势，其结果可以用直流放电的帕邢定律得到很好的解释。在10和20Pa气压下，放电的阴极鞘层区、正柱区、阳极辉光区中的转动温度都随放电电压呈现出了不同的变化趋势，甚至是完全相反的变化趋势。我们认为这是由于气压不同时，放电状态不同所致：气压为10Pa时的放电是正常辉光放电，而气压为时20Pa的放电为反常辉光放电。     

硼对电感耦合等离子体激发温度的影响

研究了制样时加入的硼酸或硼酸盐对感耦等离子体原子发射光谱的基本参数--等离子体激发温度的影响.测温实验用Fe线为温标线,采用多谱线Boltzmann作图法测量含有不同四硼酸钠浓度的溶液进样时的等离子体激发温度.测定结果表明,采用不同lg(gf)文献值计算所得的激发温度有所差距,但是同一lg(gf)文献值下测得的不同硼浓...     

Characteristics of semiconductor bridge (SCB) plasma generated in a micro-electro-mechanical system (MEMS)

Plasma ignition method has been applied in various fields particularly to the rocket propulsion, pyrotechnics, explosives, and to the automotive air-bag system. Ignition method for those applications should be safe and also operate reliably in hostile environments such as; electromagnetic noise, drift voltage, electrostatic background and so on. In the present Letter, a semiconductor bridge (SCB) plasma ignition device was fabricated and its plasma characteristics including the propagation speed of the plasma, plasma size, and plasma temperature were investigated with the aid of the visualization of micro scale plasma (i.e., ⩽350 μm), which generated from a micro-electro-mechanical poly-silicon semiconductor bridge (SCB).     

叠氮化铅的等离子体电子作用机理初探

本文分析了装有不同药剂的半导体桥（Semiconductor Bridge,SCB）火工品的电流信号,结合叠氮化铅（Lead Azide,LA）的铅核反应机理,探索性地分析了等离子体中电子对药剂分解反应的影响.表明SCB等离子体中的电子可能直接参与铅核的生成反应,使Pb²⁺/Pb⁰转化变得容易,实现6.89μs的发火.     

叠氮化铅的等离子体电子作用机理初探

本文分析了装有不同药剂的半导体桥（SCB）火工品的电流信号,结合LA的铅核反应机理,探索性地分析了等离子体中电子对药剂分解反应的影响。表明SCB等离子体中的电子可能直接参与铅核的生成反应,使Pb2+/Pb0转化变得容易,实现6.89µs的发火。     

Intermolecular structural homogeneity of metallocene polyethylene copolymers

Direct proof of intermolecular compositional inhomogeneity of a metallocene polyethylene copolymer has been obtained using a cross-fractionation (CF) technique. The ethylene/1-hexene copolymer sample was synthesized using a Zr-based homogeneous metallocene catalyst. A solvent gradient fractionation (SGF) applied to the whole polymer material has produced nearly monodispersed molecular weight distribution fractions. The component molecules of a representative SGF fraction are then further sorted out, using a temperature gradient fractionation technique, according to their short-chain branching (SCB) differences. Molecular characterization of the resulting CF fractions reveals the presence of significant intermolecular SCB content differences among the components of the sample material.     

小尺寸瞬态等离子体电子密度光谱法试验研究

本文对SCB等离子体发射光谱进行了试验研究,在局部热力学平衡条件下,用AlⅠ394.40nm谱线Stark的展宽法测量了SCB等离子体的电子密度;在发射光谱和Saha方程理论的基础上,设计并建立一套测试仪器,时间分辨率为0.1μs,将其测量的电子密度与同种试验条件下的Stark展宽法得到的结果相比较,电子密度的数量级都为1015cm-3－1016cm-3,且随时间的变化的规律相同。     

Charge oscillations in superconducting nanodevices coupled to external environments

Charge oscillations in certain nanodevices, more specifically the so-called Superconducting Cooper Pair Boxes (SCB), are usually interpreted as an effect of macroscopic quantum coherence; an alternative explanation is however possible in terms of the Gross-Pitaevski equation for the classical order parameter. These two explanations are based on different quantum states assigned to the SCB, occupation number states in the first case, coherent-like states in the second one. We show that, when the SCB is weakly coupled to an external source of noise and dissipation, occupation number states are much more unstable than coherent ones.     

4-戊基-4'-氰基联苯液晶的分子二阶非线性光学极化率测量方法

在玻璃衬底上制得单层硬脂酸的Langmuir-Blodgett(LB)膜,做为4-戊基-4''-氰基联苯(5CB)液晶的取向层,在取向层上旋涂一层5CB液晶,用透射二次谐波方法测量出5CB液晶分子二阶非线性光学极化率,其值为β=7×10-29esu.对比文献值,测量得到的结果符合较好.     

Synthesis and photoluminescence characteristics of (Sr, Ca)3B2O6:Eu for application in white light-emitting diodes

A series of yellow-green (Sr, Ca)₃B₂O₆:Eu phosphors have been synthesized using precursors prepared via a facile sol-gel route. The solid-solution phases crystallized to materials with the formula of Sr_3−x−yCa_xEu_yB₂O₆ with varied Ca²⁺ and Eu²⁺ contents. The emission peak centered at 540 nm under near-UV excitation exhibited a broad-band distribution in the range of 450-650 nm. The dependences of the luminescence intensity on the contents of Ca²⁺ substitution and Eu²⁺ dopant were also investigated. The composition in the host lattice sensitively affected the chromaticity index. Sr_1.21Ca_1.7Eu_0.09B₂O₆ (SCB:0.09Eu) was shown to possess the highest intensity and broadest emission band. Calcining temperature was shown to greatly influence the luminescent properties of SCB:0.09Eu. It is concluded that SCB:0.09Eu can be used as an efficient yellow-green phosphor for white light-emitting diodes (white LEDs) applications.     

Synergism of sweeping frequency ultrasound and deep eutectic solvents pretreatment for fractionation of sugarcane bagasse and enhancing enzymatic hydrolysis

Sugarcane bagasse (SCB) is an abundant agricultural waste in China and the conversion of the waste into plethora of useful resources is very vital. To achieve this, fractionation of the waste is highly important in the biomass biorefinery. The present study aims at investigating the synergistic role of deep eutectic solvents (DES) with sweeping frequency ultrasound (SFUS) and fixed frequency ultrasound (FFUS) in the fractionation of SCB to enhance the enzymatic saccharification process. Therefore, the effects of ultrasound (US) and DES conditions on the pretreatment efficiency were investigated. Under optimum SCB pretreatment conditions, FFUS (40 kHz, 60 min) + DES (choline chloride (ChCl)-lactic acid (LA), 120 °C, 3 h) and SFUS (40 kHz, 60 min) + DES (ChCl-LA, 120 °C, 3 h), the lignin removal rates were 80.13 and 85.62%, respectively. The hemicellulose removal rates were 78.08 and 90.46%, respectively; and the contents of glucose, xylose and arabinose in the liquid fractions after FFUS + DES pretreatment were 7.07, 17.95 and 3.01%, respectively. However, the yield of glucose, xylose, and cellobiose after enzymatic hydrolysis of the SFUS + DES pretreated SCB were 86.76, 38.68, and 20.76%. Analytical studies revealed that the SFUS + DES pretreatment can effectively destroy the ultrastructure of SCB and reduce the crystallinity of cellulose. Furthermore, the mechanism of pretreatment with SFUS + DES was proposed, which confirmed the excellent performance of SFUS + DES. Thus, the application of SFUS + DES pretreatment was able to improve the removal of lignin and hemicellulose from SCBs.