A study of the suppression of the high-temperature helium embrittlement in an oxide-particle dispersion strengthened alloy

In this paper, an investigation on the micro-structure of an Fe-base oxide-dispersion-strengthened (ODS) alloy irradiated with high-energy Ne-20 ions to different doses at a temperature around 0.5T(m) (T-m is the melting point of the alloy) is presented. Investigation with the transmission electron microscopy found that the accelerated growth of voids at grain-boundaries, which is usually a concern in conventional Fe-base alloys under conditions of inert-gas implantation, was not observed in the ODS alloy irradiated even to the highest dose (12000 at.ppm Ne). The reason is ascribed to the enhanced recombination of point defects and strong trapping of Ne atoms at the interfaces of the nano-scale oxide particles in grains. The study showed that ODS alloys have good resistance to the high-temperature inter-granular embrittlement due to inert-gas accumulation, exhibiting prominence of application in harsh situations of considerable helium production at elevated temperatures like in a fusion reactor.

Measurement of total reaction cross section for neutron-rich nucleus Li-11 on Si-28 target at medium energy

The neutron-rich nucleus Li-11 is separated by the radioactive ion beam line RIBLL at HIRFL from the breakup of 50MeV/u C-13 on Be target. The total reaction cross sections for Li-11 at energies range from 25 to 45MeV/u on Si target have been measured by using the transmission method. The experimental data at high and low energies can be fitted well by Glauber model using two Gauss density distribution. The matter radius of Li-11 was also deduced.

Influence of isospin dependence of nucleon-nucleon cross section and momentum dependent interaction on the isoscaling in intermediate energy collisions

The influences of the isospin dependent in-medium nucleon-nucleon cross section and the MomentumDependent Interaction(MDI) on the isotope scaling have been investigated within the Isospin dependent Quantum Molecular Dynamics Model(IQMD). The results show that both the isospin dependent in-medium nucleon-nucleon cross section and the momentum interaction reduce the isoscaling parameter a appreciably, which means they decrease the dependence of yield ratios of two systems on the isospin difference between two systems.

High sensitivity beam phase measurement system for isochronous cyclotron

The beam phase measurement system in the HIRFL is introduced. Based on the double-balanced mixer principle using rf-signal mixing and filtering techniques, a stable and sensitive phase measurement system has been developed. The phase history of the ion beam is detected by using a set of capacitive pick-up probes installed in the cyclotron. The phase information of the measurement is necessary for tuning to obtain a optimized isochronous magnetic field which induces to maximize the beam intensity and to optimize the beam quality. The result of the phase measurement is reliable and the accurancy reaches +/- 0.5 degrees.

Experimental study of the high-voltage breakdown and simulations for the RFQ cooler and buncher RFQ1L

The RFQ cooler and buncher RFQ1L is one of the key parts of the being-built super-heavy nuclide research spectrometer. In order to understand the high-voltage breakdown phenomenon, the voltages between electrodes have been measured. In addition, more extensive simulations have been performed for better understanding and optimizing the RFQ1L work points.

Probing density-dependent symmetry energy by using the double n/p ratio

Based on a transport model IBUU04, the double n/p ratio is studied. It is found that the double n/p ratio has almost the same sensitivity to the density dependence of nuclear symmetry energy as the single n/p ratio does. Because the double n/p ratio of nucleon emissions taken from two reaction systems can reduce systemic errors effectively, it is thus more useful for constraining the density-dependent symmetry energy further.

Study of unbound nuclei N-11 resonance energy level

The excitation functions of elastic scattering proton which were measured with inverse kinematics of elastic resonance scattering reactions in GANIL and MSU have been fitted by the multi-energy level R-matrix theory. The final result shows that the new energy levels order for nucleus N-11 should be 1/2(+), 1/2(-), 5/2(+), 3/2(+), 3/2(-), 5/2(+), 7/2(-), which is consistent with the experimental results of Be-11 (the mirror nucleus of N-11) and the theoretical calculation of N-11 with GCM theory.

An online monitor ionization chamber used in particle therapy

The clinical trials of tumor therapy using heavy ions beam C-12 are now in progress at Institute of Modem Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy C-12 beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy C-12 beam in active pencil beam scanning mode.

Fluorene-Based Copolymers Containing Dinaphtho-s-indacene as New Building Blocks for High-Efficiency and Color-Stable Blue LEDs

By incorporating a new building block, 7,7,15,15-tetraoctyldinaphtho-s-indacene (NSI), into the backbone of poly(9,9-dioctylfluorene) (PFO), a novel series of blue light-emitting copolymers (PFO-NSI) have been developed. The insertion of the NSI unit into the PFO backbone leads to the increase of local effective conjugation length, to form low-energy fluorene-NSI-fluorene (FNF) segments that serve as exciton trapping sites, to which the energy transfers from the high-energy PFO segments. This causes these copolymers to show red-shifted emissions compared with PFO, with a high efficiency and good color stability and purity. The best device performance with a luminance efficiency of 3.43 cd . A(-1), a maximum brightness of 6 539 cd . m(-2) and CIE coordinates of (0.152, 0.164) was achieved.

Crystallization of mechanically alloyed amorphous W-Mg alloy under high pressure

Pure metal powder mixtures of W and Mg at the desired composition were milled in conventional high-energy ball mill, and amorphous alloy W50Mg50 was obtained after milling for 20 h. The structure evolution of elemental powder mixtures was studied following milling and subsequent high pressure and high temperature treatment. The amorphous alloy transform into a nanocrystalline material below 1050 degreesC at 4.0 GPa. On increasing the temperature, it transforms into a mixture of several new crystal phases under high-pressure condition. It also found that both mechanical alloying and high pressure treatment are the two necessary processes to form the nanocrystalline and the new phases.

MODIFICATION OF POLYTETRAFLUOROETHYLENE BY RADIATION .1. IMPROVEMENT IN HIGH-TEMPERATURE PROPERTIES AND RADIATION STABILITY

Polytetrafluoroethylene (PTFE) has never been reported to form a network structure when subjected to high energy radiation. Results obtained in this work indicates that when irradiation is performed under 330-340-degrees-C in vacuo PTFE can be crosslinked

镀铬/高能束复合表面处理研究进展

根据高能束对镀铬涂层及其界面强化机制的不同,镀铬/高能束表面复合技术可分为两类:高能束强化镀铬涂层复合技术和高能束预处理基体/镀铬复合技术.前者典型代表有激光表面强化或等离子体氮化/镀铬涂层;后者主要代表是激光预淬火基体/镀铬复合表面处理.综合阐述了上述3种典型的复合处理技术的原理、目的及实际综合效果;通过试验初步探讨了激光预淬火基体/镀铬复合技术延长镀铬身管寿命的主要机理.

低渗油田“层内爆炸”增产技术的小尺度模拟实验研究

本文是关于低渗油田增产技术的室内模拟实验研究的论文。我们对井内爆炸采油、核爆采油和高能气体压裂进行全面调研以后，吸取了井内爆炸采油的教训，借鉴了高能气体压裂的成功经验，提出了低渗油田“层内爆炸”增产技术。该技术是利用水力压裂技术的现有设备，将适当的炸药压入岩石裂缝，再用适当的方法起爆，从而在岩石裂缝周围产生大量裂缝，在不会对储层产生不利影响也不会毁坏井筒的前提下，达到提高采取收率并增产油气的目的。首先，建立了圆管点火实验装置、小尺度模拟实验装置和平板点火实验装置；然后利用实验装置进行了“层内爆炸”用特种火药和特种炸药配方的探索。通过实验我们至少找到了一种“层内爆炸”用药品的配方，并且在小尺度模拟实验装置中实现了“层内爆炸”基本过程的模拟实验，从而证实“层内爆炸”思路正确，原理上可行。接着，建立了爆燃推进的模型，并在恒稳推进和不可压缩简化条件下得到几组算例，这些解在物理上是合理的。通过计算我们得知爆燃恒温推进的条件是苛刻的，需要多个参数的匹配。通过本人硕士论文的工作，证实了低渗油田“层内爆炸”增产技术在原理上的可行性。但因为“层内爆炸”过程中牵涉到多个特征尺度，因此并不能从小尺度向大尺度简单地推广，下一步工作是建立中大尺度模拟实验装置，考察在中大尺度条件下“层内爆炸”的可行性，为现场实际应用作充分的实验准备。

Interactions of a femtosecond intense laser with rare gas clusters in a dense jet\

A study on the interactions of high intensity (similar to 10(16) W/cm(2)) femtosecond laser pulses with rare gas clusters in a dense jet is performed. Energy absorption by Ar and Xe clusters is measured and it can be as high as 90%. Very energetic ions produced in the laser interaction with a dense cluster jet are detected by time-of-flight spectrometry and the maximum ion energy of Xe is up to 1.3 MeV. The average ion energies are found to increase with increasing cluster size and get saturated gradually. The average ion energies also show a strong directionality and the average ion energy in the direction parallel to the laser polarization vector is 40% higher than that perpendicular to it. The findings are discussed in terms of a model of charge-dependent ion acceleration.

高能离子在稠密等离子体中的传输和能量沉积

用相对论福克-普朗克方程对高能离子在稠密氘氚等离子体中的碰撞动力学进行了研究,用球谐函数来展开方程的解：格林函数,然后简明地求出了不同能量质子和α粒子在等离子体中的停止时间、减速距离、纵向弥散距离和横向偏转距离.与以前研究离子在等离子体中运动的方法相比,没有假设高能离子在等离子体中损失能量远远小于入射离子能量,求解了纵向弥散距离;并且可以求解横向偏转距离.这些计算对实验上用高能离子加热冷的稠密等离子体,然后进行科学研究具有指导作用,并且可以用来研究快点火的可能性.