HLS逐束团跟踪监测系统

介绍了合肥光源(HLS)逐束团跟踪监测系统, 并且展示了相关的实验、数据分析 结果. 通过同相的门电路信号和RF的分频信号控制ADC的外触发, 对该测量系统的可靠性、稳定性进行了验证. 并且利用该系统, 跟踪记录了完整的注入, 慢加速, 降频, 校正轨道, 扭摆磁铁充电, 加斜四极铁以及正常供光运行的全过程. 最后展示了该过程的横向工作点(tune值)漂移, 多束团耦合不稳定性的研究结果.     

合肥电子储存环束流不稳定性的抑制

 合肥光源二期工程改造的电子储存环调试过程中，发现多束团存储和运行时存在耦合束团不稳定性，严重地限制了注入的最高流强，并且影响了光源运行的质量。通过过正地增大正色品以及在储存环上插入八极磁铁，基本上抑制了横向的耦合束团不稳定性，保证了稳定注入束流300 mA的技术指标。     

1,2-环氧辛烷的同步辐射光电离解离研究

利用同步辐射产生的真空紫外光和反射式飞行时间质谱仪,在超声冷却条件下测量了1,2-环氧辛烷在光子能量9.8~16.6 eV能区的光电离解离过程,获得了不同能量光子作用下的电离解离产物。通过测量各离子的光电离效率曲线,得到了主要碎片离子的出现势。结合G3理论计算得到了母体离子、中性碎片及离子碎片的结构与能量,通过对比实验测量值与理论值给出了1,2-环氧辛烷的光电离解离通道.     

Dissociative Photoionization of 1,2-Epoxyoctane Studied with Synchrotron Radiation

Dissociative photoionization of 1,2-epoxyoctane was investigated by synchrotron radiation vacuum ultraviolet photons in the energy region of 9.8-16.6 eV under ultrasonic molec-ular beam. Dissociative fragment ions were measured with reffection time-of-ight mass spectrometer at di erent photon energies. Appearance potentials of the dominative ion fragments were determined through photoionization efficiency curves. The structures and energies of the parent, ionized and neutral radicals were obtained with G3 calculations. Through comparing the experimental results with the theoretical calculations, we proposed the dissociative channels for the photoionization of 1,2-epoxyoctane.     

A theoretical interpretation of free volume at glass transition

We device a relaxed lattice model (RLM) to study the mechanism of glass transition,which unifies the cageeffects from particle-particle interaction and entropy.By analyzing entropy in RLM with considering the influence of interactions on equilibrium,we demonstrate that glass transition is a second-order phase transition.For a perfect onedimensional linked particle system like linear polymer under normal pressure,the free volume at glass transition is rigorously deduced out to be 2.6％,which provides a theoretical basis for the iso-free volume of 2.5％ given by Willian,Landel and Ferry (WLF) equation.Extending to system with dead particles linked with higher dimensions like branched or cross-linked chains under positive or negative pressure,free volume at glass transition is varied,based on which we construct a phase diagram of glass transition in the space of free volume-dead particle-pressure.This demonstrates that free volume is not the single parameter determining glass transition,while either dead particles like cross-linked points or external force fields like pressure can vary free volume at the glass transition.     

Rhodanine flanked indacenodithiophene as non-fullerene acceptor for efficient polymer solar cells

A fused-ring electron acceptor IDT-2BR1 based on indacenodithiophene core with hexyl side-chains flanked by benzothiadiazole rhodanine was designed and synthesized.In comparison with its counterpart with hexylphenyl side-chains(IDT-2BR),IDT-2BR1exhibits higher highest occupied molecular orbital(HOMO)energy but similar lowest unoccupied molecular orbital(LUMO)energy(IDT-2BR1:HOMO=-5.37eV,LUMO=-3.67eV;IDT-2BR:HOMO=-5.52eV,LUMO=-3.69eV),red-shifted absorption and narrower bandgap.IDT-2BR1 has higher electron mobility(2.2×10~(-3)cm~2 V~(-1)s~(-1))than IDT-2BR(3.4×10~(-4)cm~2 V~(-1)s~(-1))due to the reduced steric hindrance and ordered molecular packing.Fullerene-free organic solar cells based on PTB7-Th:IDT-2BRl yield power conversion efficiencies up to 8.7%,higher than that of PTB7-Th:IDT-2BR(7.7%),with a high open circuit voltage of0.95 V and good device stability.     

束流轨道快校正磁铁电源研究进展

快校正磁铁电源能够对束流轨道的偏离进行快速校正,提升同步辐射光源运行的可靠性。随着第四代衍射极限储存环(DLSR)光源品质的进一步提高,为了保证束流轨道的稳定性,快速轨道反馈(FOFB)系统对校正磁铁电源的性能也提出了更高的要求。针对先进同步辐射光源FOFB系统对快校正磁铁电源的需求,将目前国内外第四代同步辐射光源束流轨道快速校正磁铁电源的研究成果分为线性电源和开关电源两类,对各方案的拓扑结构、控制策略以及性能参数的特点等进行了简要对比分析,可以看出目前国内外正在研制的快校正磁铁电源响应带宽基本可以达到5 kHz甚至10 kHz水平,线性电源的低纹波噪声特性具备应用优势但需要关注效率低的问题;开关电源方案具有高效、模块化等特点,如果可以有效解决纹波噪声问题,将会更广泛地应用在快校正磁铁电源的设计中。     

A detailed high-pressure oxidation study of di-isopropyl ether

The oxidation of di-isopropyl-ether (DIPE) was studied in a jet-stirred reactor. Fuel-lean, stoichiometric, and fuel-rich mixtures (φ = 0.5–4) were oxidized at a constant fuel mole fraction of 1000 ppm, at temperatures ranging from 500 to 1160 K, at 10 atm, and constant residence time of 0.7 s. The chosen conditions are consistent with our previous studies on ether oxidation. Mole fraction profiles were obtained through sonic probe sampling, and analyzed by gas chromatography and Fourier transform infrared spectrometry. As opposed to our previous studies on ethers (S. Thion et al. 2017, Z. Serinyel et al. 2018 and 2020), DIPE showed no low-temperature reactivity under the same experimental conditions. Oxidation of the rich mixture showed similarities to pyrolysis producing important quantities of propene and isopropanol, while no isopropanol is observed under lean conditions. In terms of overall reactivity, DIPE showed smaller fuel conversion compared to other symmetric ethers previously studied. The present data and literature experiments were simulated with our ether oxidation mechanism showing good agreement.     

Establishment of a set of skeletal oxidation mechanisms for mono-alkylated cyclohexanes with consistent structure

As a major chemical class of fossil fuels, mono-alkylated cyclohexanes are frequently employed to construct the surrogate fuels of fossil fuels. Much effort has been made to study the oxidation behavior of mono-alkylated cyclohexanes, but reduced/skeletal mechanisms suitable for multi-dimensional combustion simulations are still scarce. In this work, a set of skeletal models for mono-alkylated cyclohexanes from methyl-cyclohexane (MCH) to octyl-cyclohexane (n-OTCH) were built and deduced by integrating the decoupling methodology and reaction rate rules. The development process contains two parts, i.e., the skeletal model establishment for the base fuel and the skeletal model deduction for other fuels utilizing the reaction rate rules. For mono-alkylated cyclohexanes, the reactions in the fuel-relevant sub-model also dominate the laminar flame speed, apart from the C₀–C₃ sub-model, which differs from that of n-alkanes. To well capture the flame propagation behavior, the local sensitivity analysis on the comprehensive mechanism was introduced. For each mono-alkylated cyclohexane, the skeletal model includes 52 species and 216 reactions. The final skeletal models were validated against extensive experimental measurements in jet-stirred reactors, shock tubes, rapid compression machines, and premixed flames over wide operating conditions. Satisfactory agreements between the observed data and simulated results are achieved, which indicates the practicability of the proposed method.     

Experimental and kinetic modeling study on auto-ignition properties of ammonia/ethanol blends at intermediate temperatures and high pressures

The auto-ignition properties of ammonia (NH₃)/ethanol (C₂H₅OH) blends close to engine operating conditions were investigated for the first time. Specifically, the ignition delay times (IDT) of ammonia/ethanol blends were measured in a rapid compression machine (RCM) at elevated pressures of 20 and 40 bar, five C₂H₅OH mole fractions from 0% to 100%, three equivalence ratios (ϕ) of 0.5, 1.0 and 2.0, and intermediate temperatures between 820 and 1120 K. The measurements reveal that ethanol can drastically promote the reactivity of ammonia, e.g., the auto-ignition temperature with merely 1% C₂H₅OH in fuel decreases accordingly around 110 K at 40 bar as compared to that of neat ammonia. Moreover, the promotion efficiency of ethanol is higher than hydrogen and methane with a factor of 5 and 10 under the same condition. Different dependences of IDT on the equivalence ratio were observed with different ethanol fractions in the blends, i.e., the IDTs of the 5%, 10% and 100% C₂H₅OH in fuel decrease with an increase of ϕ, but an opposite trend was observed in the mixture with 1% C₂H₅OH. A new chemical kinetic mechanism for NH₃/C₂H₅OH mixtures was developed and it is highlighted that the addition of cross-reactions between the two fuels is necessary to obtain reasonable simulations. Basically, the newly developed mechanism can reproduce the measurements of IDT very well, whereas it overestimates the reactivity of the stoichiometric and fuel-rich mixture with 1% C₂H₅OH in fuel. The sensitivity, reaction pathway, as well as rate of production analysis indicated that the ethanol addition to ammonia fuel blends provides key interaction pathways and enriches the O/H radical pool which further promotes the auto-ignition process.