ALE finite elements with hydrodynamic lubrication for metal forming

Computer simulation methods for metal forming processes based on Arbitrary Lagrangian-Eulerian (ALE) finite elements, adaptive mesh deployment techniques and hydrodynamic lubrication finite elements are developed. The emphasis is placed on the interaction of the tool and metal workpiece by including the effects of lubricant flow, pressure gradient, film entrainment, surface roughness and sliding. It provides a more realistic modeling of contact, lubrication, and frictional stresses.     

Diagnostics for Lab and Astrophysical Plasmas

To monitor effects of vacuum conditioning, three radiation diagnostics are being built: a Helium–Neon (HeNe) heterodyne interferometer, a Bolometer, and a Hydrogen-alpha (Hα) detector. The interferometer will measure the line-average refractive index of the plasma, enabling us to obtain the line average density. The bolometer is a soft X-ray/UV detector (similar to those used on the Sustained Spheromak Physics Experiment (McLean et al. in Rev. Sci. Instruments 72(1):556–561, 2001) and the High-Beta Tokamak Experiment (Xiao and Navratil. in Rev. Sci. Instrument 67(9):3334–3335, 1996) and is used to directly measure the radiation loss from photons. The Hα detector will detect the amount of Hα being emitted by the plasma as a function of time, thus gauging the neutral density. These same concepts are also applied to astrophysical plasmas, with slightly different approaches. A brief overlap between diagnostics/detectors for laboratory and astrophysical plasmas is discussed.     

A posteriori error estimator and AMR for discrete ordinates nodal transport methods

In the development of high fidelity transport solvers, optimization of the use of available computational resources and access to a tool for assessing quality of the solution are key to the success of large-scale nuclear systems’ simulation. In this regard, error control provides the analyst with a confidence level in the numerical solution and enables for optimization of resources through Adaptive Mesh Refinement (AMR).     

中国实验快堆额定工况下冷热钠池数值分析

应用计算软件STAR-CD对中国实验快堆(CEFR)正常运行工况中的额定工况进行了三维数值分析，使用多孔介质模型对屏蔽柱的影响进行了模拟，给出了冷热钠池的三维温度场和流场，与已有热工设计进行了比较，并着重分析了浮升力在数值模拟计算中的影响，为事故工况下的设备动态分析及相应的设备力学分析提供了数据。研究结果为CEFR的优化设计及事故分析提供了参考数据和技术支持。     

Resonance Interaction Effect between Hot Sample and Cold Core in Analysis of Doppler Effect Measurement

The resonance interaction effect between hot sample and adjacent cold core was evaluated in a small sample ²³⁸U Doppler effect measurement. For this analysis a collision probability code with an ultra-fine group structure PEACO-X was developed. The previously measured Doppler effect reactivity coefficients at FCA are systematically analyzed by using the PEACO-X code. The results were compared with the conventional calculation results using the SLAROM code. From these results, it was shown that this effect depends on the background cross section for ²³⁸U in a core, and also depends on the radius and density of the sample. When this resonance interaction effect is taken into account, the calculated Doppler reactivity worths becomes larger than those using the conventional method and the sample dependency of calculation disappeared. The reliability of Doppler effect calculation was significantly improved.     

Charge and Mass Considerations for Plasma Velocity Measurements in Rotating Plasmas

Velocity of hydrogen plasmas rotating due to imposed E × B fields at the Maryland Centrifugal Experiment (MCX) (Ellis et al., Phys Plasmas 12:055704, 2005), where E is the electric field in the radial direction and B the magnetic field in the axial direction of a cylindrical configuration, has traditionally been measured using Doppler shifts of atomic spectra from impurity elements such as carbon. Ideally, the gyrocenter of trace particles rotates at the bulk plasma velocity, regardless of the charged state or trace particle mass. However, for sufficiently large applied |E/B| (or equivalently, a sufficiently large ratio of bulk plasma rotation frequency and particle gyrofrequency), charged particles may have gyroradii that depart significantly from quasi-circular orbits drifting about the B field axis. This effect is investigated numerically with a single particle code that includes scattering, as well as experimentally at MCX. Numerical findings are compared to experimentally measured Doppler shifts of singly inonized helium and oxygen, and doubly ionized carbon atoms.     

Contrasting Behaviours of AC and DC Excited Plasmas in Contact with Liquid

A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations is detailed in this paper. All plasmas studied here are shown to be glow discharges. This study is based on measurements of several key parameters, including electrical energy, optical emission intensities of active species, rotational and vibrational temperatures, and temperatures of the needle and liquid electrodes. AC plasmas can produce 1.2～5 times higher excited state active species than DC plasmas under the same dissipated power. AC excited liquid plasmas have the highest energy utilization efficiency among the three systems (AC excited plasmas, DC excited plasmas with water anode and DC excited plasmas with water cathode); most of the energy is used to produce useful species rather than to heat the electrodes and plasmas.     

Compaction of Radioactive Thermal-Insulation Materials and Construction Debris by Melting in a Cold Crucible

A technology is proposed for reprocessing radioactive thermal-insulation materials and construction debris, produced at nuclear power plants and radiochemical facilities, by melting the wastes in a induction furnace with a cold crucible. The results show that the final volume of the thermal-insulation wastes can be decreased by a factor of 40 and that of the construction debris by a factor of 2.5. The high hydrolytic stability of the final materials produced as a result of melting (the ¹³⁵Cs and ⁹⁰Sr leach rate is less than 1·10⁻⁷ g/(cm²·day) allows these wastes subsequently to be stored and buried. Recommendations are developed for an apparatus-technological scheme and for electrotechnical equipment for a commercial facility. __________ Translated from Atomnaya Energiya, Vol. 99, No. 3, pp. 167–171, September, 2005.     

Four-fluid Model and Radial Transport Equation for Toroidal Momentum in Tokamak Plasmas

1. IntroductionIn order to explain some recent experiment resultsand find new ways to improve the plasma performance: the study of the toroidal momentum transport and the spacial structure of radial electric fieldhave drawn more and more attention in tokamakplasma research [l,2,3,4]. To date, the theoreticalanalysis of plajsma toroidal momentum transport hasbeen mainly based on the ordinary MHD model.However, the ordinary MHD model fails to deal withconstraint conditions on the motions of th…     

中低温稠密等离子体电子压强的自洽场计算

对含温有界自洽场平均原子结构中自由电子的判据做了修改,用分波法和Fermi-Dirac统计处理自由电子。在计算电子压强时考虑了共振态和交换、库仑关联对压强的影响。计算并与实验比较了Ni,Cu的零温电子压强。以Fe,Pb为算例,展示了平均原子模型的适用性。     

Spherical and Cylindrical Ion Acoustic Shock Structures in Plasmas with q-Nonextensive Electron Velocity Distribution

The propagation of ion acoustic shock waves in cylindrical and spherical geometries has been investigated. The plasma system consists of cold ions, nonextensive electrons and thermal positrons. Spherical and cylindrical Korteweg–de Vries–Burger equations have been derived by reductive perturbation method and their shock behavior is studied by employing finite difference method. It is found that shock waves can be produced in this medium. The important effects of the q-nonextensive electron on the properties of ion acoustic waves are discussed. Furthermore, it is observed that the positron concentration, ratio of electron to positron temperature, geometry parameter and the plasma kinematic viscosity significantly modifies the shock structure.     

基于附加源项法的钠冷快堆冷热池三维分析

选择计算流体动力学(CFD)为模拟手段,建立快堆一回路钠池的三维闭式一体化CFD模型,对一回路中主要部件进行模拟,其中中间热交换器、独立热交换器、堆芯、主泵采用附加源项法进行模拟,得到中国实验快堆(CEFR)额定功率稳态运行时整个流场的三维速度场与温度场。计算值同CEFR设计值进行比较,结果符合预期,证明了模型的合理性。计算结果表明,钠池较明显地分为温度较低的冷钠池和温度较高的热钠池2个部分,热钠池温差较大,冷热流体搅混现象明显;同时冷钠池、热钠池不同高度的平均温度都很接近,说明分隔冷热钠池的热屏蔽效果较好。     

MHD Instabilities and Their Effects on Plasma Confinement in Large Helical Device Plasmas with Intense Neutral Beam Injection

MHD stability of the Large Helical Device (LHD) plasmas produced with intense neutral beam injection is experimentally studied. When the steep pressure gradient near the edge is produced through L-H transition or linear density ramp experiment, interchange-like MHD modes whose rational surface is located very close to the last closed flux surface are strongly excited in a certain discharge condition and affect the plasma transport appreciably. In NBI-heated plasmas produced at low toroidal field, various Alfven eigenmodes are often excited. Bursting toroidal Alfven egenmodes excited by the presence of energetic ions induce appreciable amount of energetic ion loss, but also trigger the formation of internal and edge transport barriers.     

Power Plant for Heavy-Ion DT Fusion with Targets Containing Fissioning Materials

The special features of the concept of a hybrid power-generating plant, which combines the fusion and fission processes in a cylindrical target initiated by a high-power heavy-ion accelerator, are analyzed. The main advantages of the proposed setup are: burning of unenriched ²³⁸U in the reactor cavity, continuous removal of fission products from the core, and impossibility of an uncontrollable nuclear reaction. The characteristics of matched heavy ion accelerator, target, reactor chamber, and blanket with circulating coolant in the blanket are presented, and the power parameters of the electric power plant are estimated. __________ Translated from Atomnaya Energiya,Vol. 99, No. 3, pp. 190–198, September, 2005.     

Interaction of Impurity （Li, Be, B and C） and Hydrogen Isotope Pellet Injection with Reactor-relevant Plasmas

Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's     

CVD金刚石核探测材料与器件

金刚石膜因其优异的电学、光学等性能已成为优越的辐射探测器材料,但探测器性能强烈地依赖于薄膜质量.本工作利用热丝化学气相沉积(HFCVD)法获得了 (100)取向不同质量的金刚石薄膜,并制备了CVD金刚石辐射探测器.应用5.9 keV 55Fe X射线测试了探测器的光电流响应和脉冲高度分布.50 kV/cm外电场作用下晶粒为10 μm的CVD金刚石探测器的暗电流和光电流分别为16.3和16.8 nA.光电流随辐照时间延长而增大,尔后趋于稳定.脉冲高度峰与噪声明显分离.探测器具有较高的计数效率和信噪比.     

Thermal Conductivity Measurement with Silica-Coated Hot Wire for Li4SiO4 Pebble Bed

The effective thermal conductivity of a Li₄SiO₄ pebble bed was measured by the hot wire method. The bare and silica-coated Nichrome heaters were used as the hot wires. At 975 K, effective thermal conductivity was not measured correctly by the bare hot wire. This is due to the fact that the electrical signal of a bare thermocouple is distorted due to the electrical conductivity of Li₄SiO₄. Using a silica-coated hot wire, effective thermal conductivity can be measured at temperatures ranging from room temperature to 975 K. The effect of the coating layer on the measured effective thermal conductivity was estimated to be small and corresponded to the experimental data. The hot wire method with silica coating can be applied to other ceramic breeder materials.     

A Simple Relation for Effective Neutron Temperature in Cold Moderators with Lattice Vibrational Modes

The effective neutron temperature in cold hydrogenous solid moderators is analyzed in phonon approximation with use made of two simple models representing the frequency distribution of lattice vibrations, and simple relations are derived between the variation of the effective neutron temperature and the moderator temperature, as also, an equation expressing the limiting neutron temperature in a moderator at absolute zero temperature.

Good agreement is obtained between the calculated and experimental results in cold light water ice. It is indicated that unbounded cooling of the moderator is not necessarily effective in improving the moderating efficacy, in the case of slowing-down by lattice vibrations; it generally suffices to cool the moderator down to the limiting neutron temperature.

It is revealed that approach of the neutron temperature to the limiting value is largely determined by the shape of the frequency distribution of the lattices, while the limiting value itself is influenced by such parameters as the Debye temperature, the molecular mass and the ratio of absorption to the scattering cross section in the moderator. As a result of the present analysis, a general method for comparing and evaluating various solid moderators for cold neutrons has been established for practical use.     

Modeling and Test Verification for Hardened Integrated Circuits

Hardened dielectrically isolated integrated circuits are being developed to provide an order of magnitude improvement in radiation response over previous bipolar technology. This paper describes (a) the analytical and experimental techniques used to develop the hardened parts, and (b) comparative analytical and test results obtained thus far in the program. The paper describes how (a) various "element" models were defined for CAD usage, (b) how design tolerances were established for the element models, (c) how circuit design margins were established, (d) experimental techniques and equipment used to validate early designs, and (e) comparative analytical and test results.     

直流蒸汽发生器给水控制半实物仿真系统

采用直流蒸汽发生器的核动力装置是一个多变量耦合的复杂被控对象,为了对其给水控制系统进行研究,设计了一个直流蒸汽发生器给水控制半实物闭环仿真系统.该系统由实时仿真系统、给水控制系统物理设备和仿真过程管理系统组成.给水控制系统物理设备采集实时仿真系统提供的参数信号,并输出控制信号至电动执行机构.半实物闭环控制仿真试验表明,该仿真系统具有较好负荷跟踪能力,可为实际直流蒸汽发生器控制系统的设计及运行提供技术指导.