共查询到20条相似文献,搜索用时 46 毫秒
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介绍了用于计算中性束注入实验中束流功率沉积的水流热量计系统优化及优化后的测试结果。前期的水流热量计系统利用串口传输和分散式牛顿模块采集,采样率低、传输速度慢、抗干扰能力差、无法满足实验要求;优化后的系统基于虚拟仪器,采用TCP\IP协议传输和虚拟仪器技术,提高了系统的采样率和精度、优化了数据传输速度及抗干扰能力。优化后的系统经测试可以准确监测中性束注入器装置上各热承载部件冷却水的温升及流量,并分析得到中性束注入时束流在各热承载部件上的功率沉积。实验结果表明优化后的系统工作稳定,使用灵活,数据准确,满足实验要求。 相似文献
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比较精确地模拟计算中性束注入(NBI)托卡马克等离子体的快离子初始分布是采用大规模数值模拟方法研究NBI快离子相关物理问题的首要任务。本文建立了NBI托卡马克等离子体的简化物理模型,采用蒙特卡罗方法自主开发了NBI应用程序。选取ASDEX Upgrade(AUG)托卡马克上切向注入和垂直注入两种情况为计算实例,分别模拟计算出NBI粒子被离子化的初始三维空间位置,并统计得出初始快离子的径向分布、极向角分布、环向角分布和投掷角分布,这些计算结果与国际上相关文献结果一致。 相似文献
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弧电源是中性束注入加热系统中最关键的设备之一,它的性能决定了弧放电的稳定性及束流引出的品质。为提高弧放电稳定性,降低电网容量,减少对电网的冲击,弧电源拓扑设计采用了基于超级电容储能和开关电源技术的DC/DC变换器结构。利用多个IGBT功率模块并联工作,可提高电源工作频率,实现更快的动态响应速度。在详细分析电源工作过程的基础上,设计了滤波电路和电流快速转移电路,根据电源的要求和具体参数,由一阶RL电路的电流响应特性,精确计算出滤波电感的最小值。最后,利用Matlab对电源性能指标进行了仿真验证,结果表明电源性能完全符合设计要求。 相似文献
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HL-1M 中性束注入器快速断电保护器 总被引:1,自引:0,他引:1
介绍了用于HL-1M中性束注入器电源系统中的一个快速断电保护器。它能快速探测注入器过黉,过流和打火击穿等运行故障并给出故障信号,以便快速分断电源,保护离子源和电源本身免于损坏。详细介绍了电路结构,工作原理和实验结果。保护器在强线路干扰和电磁干扰下可靠工作。 相似文献
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S. Gorelick F. Zhang H.J. Whitlow 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(19):3314-3318
Hydrogen silsesquioxane (HSQ) behaves as a negative resist under MeV proton beam exposure. HSQ is a high-resolution resist suitable for production of tall (<1.5 μm) high aspect ratio nanostructures with dimensions down to 22 nm. High aspect ratio HSQ structures can be used in many applications, e.g. nanofluidics, biomedical research, etc. Isolated HSQ nanostructures, however, tend to detach from substrates during the development process due to the weak adhesive forces between the resist and the substrate material. Larger proton fluences were observed to promote the adhesion. To determine an optimal substrate material and the proton irradiation doses for HSQ structures, a series of 2 μm long and 60-600 nm wide free-standing lines were written with varying fluences of 2 MeV protons in 1.2 μm thick HSQ resist spun on Ti/Si, Cr/Si and Au/Cr/Si substrates. The results indicate that the Ti/Si substrate is superior in terms of adhesion, while Au/Si is the worst. Cr/Si is not suitable as a substrate for HSQ resist because debris was formed around the structures, presumably due to a chemical reaction between the resist and Cr. 相似文献
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Secondary cosmic-ray neutron-induced soft errors in an n-type metal-oxide-semiconductor field-effect transistor are analyzed based on the multiple sensitive volume (MSV) model using Particle and Heavy Ion Transport code System (PHITS). The soft error rates (SERs) and the collected charge for each single event are compared with those obtained by PHits-HYenexss integrated code System for Effects of Radiation on Device (PHYSERD) based on the detailed technology computer-aided design (TCAD) simulation and by the single sensitive volume (SSV) model using PHITS. It is found that PHITS+MSV provides approximate SERs in a shorter time than PHYSERD by estimating collected charges without event-by-event TCAD simulation. Furthermore, PHITS+MSV reproduces collected charge for each single event more accurately than PHITS+SSV by considering spatial dependence of the charge collection efficiencies. Therefore, PHITS+MSV is the most suitable to estimate SERs in practical design of semiconductor devices which require high accuracy and a short computational time. 相似文献
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Ryota Katano Tomohiro Endo Akio Yamamoto Kazufumi Tsujimoto 《Journal of Nuclear Science and Technology》2018,55(10):1099-1109
We proposed the penalized regression ‘adaptive smooth-lasso’ for the estimation of sensitivity coefficients of the neutronics parameters. The proposed method utilizes the variation of the microscopic cross-sections and the neutronics parameters obtained by random sampling. The weighted penalty term of the proposed method is more appropriate for the estimation of the sensitivity of neutronics parameters to the microscopic cross-section than that of the conventional methods. In a numerical verification calculation, sensitivity coefficients of keff of an accelerator-driven system are estimated using the proposed method, the conventional penalized regression, and the direct method. Comparison of these results indicates that the proposed method is superior to the conventional penalized linear regression from the viewpoint of reproduction of the reference sensitivity coefficients obtained by the direct method. Through the verification calculations, the proposed method can be a candidate for a practical method to estimate the sensitivity coefficients with low calculation cost. 相似文献
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In the design of negative hydrogen ion sources,a magnetic filter field of tens of Gauss at the expansion region is essential to reduce the electron temperature,which usually results in a magnetic field of around 10 Gauss in the driver region,destabilizing the discharge.The magnetic shield technique is proposed in this work to reduce the magnetic field in the driver region and improve the discharge characteristics.In this paper,a three-dimensional fluid model is developed within COMSOL to study the influence of the magnetic shield on the generation and transport of plasmas in the negative hydrogen ion source.It is found that when the magnetic shield material is applied at the interface of the expansion region and the driver region,the electron density can be effectively increased.For instance,the maximum of the electron density is 6.7×1017 m-3 in the case without the magnetic shield,and the value increases to 9.4×1017 m-3 when the magnetic shield is introduced. 相似文献
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Laser-induced breakdown spectroscopy(LIBS) is a useful technique for accurate sorting of metal scrap by chemical composition analysis.In this work,a method for intensity-ratiobased LIBS classification of stainless steel applicable to highly fluctuating LIBS signal conditions is proposed.The spectral line pairs for intensity ratio calculation are selected according to elemental concentration and upper levels of emission lines.It is demonstrated that the classification accuracy can be significantly improved from that of full-spectra principal component analysis or intensity-based analysis.The proposed method is considered to be suited to an industrial scrap sorting system that requires minimal maintenance and low system price. 相似文献
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ABSTRACTBy introducing a new assumption of linear estimation, we derive a new formulation of the extended cross-section adjustment (EA) method, which minimizes the variance of the design target core parameters. The new formulation is derived on the basis of minimum variance unbiased estimation with no use of the assumption of normal distribution. In this formulation, we found that EA has infinitely many solutions as the adjusted cross-section set. The new formulation of EA can represent all the possible solutions minimizing the variance of the design target core parameters and includes a special case identical to the classical Bayesian EA method, which was derived on the basis of the Bayes theorem under the assumption of normal distribution. Moreover, we prove that the special case minimizes not only the variance of the design target core parameters but also the variance of the nuclear data. Meanwhile, we show that the new assumption of linear estimation is consistent with the Kalman filter and demonstrate that we can formulate similarly the extended bias factor method, the conventional cross-section adjustment method, and the regressive cross-section adjustment method with no use of the assumption of normal distribution. 相似文献
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Kosuke Tsujita Tomohiro Endo Akio Yamamoto 《Journal of Nuclear Science and Technology》2020,57(6):646-662
ABSTRACTAn efficient numerical scheme for time-dependent MOC calculations is proposed. In the present scheme, one of the most successful factorization method, the multigrid amplitude function (MAF) method, is employed to achieve faster computation with the minimum degradation for the temporal integration of the scalar flux. In addition, the MAF method is re-derived based on the linear source approximation, which is not applied for time-dependent MOC calculations in the past studies as far as the authors’ knowledge, to reduce the spatial discretization error with the coarser flux region separation. The accuracy and computational time of the present scheme are evaluated through the calculation of the TWIGL and the C5G7-TD 2D benchmark problems. The present calculation results show that the present scheme is 6.2 times faster than the conventional method while achieving the same accuracy in the C5G7-TD benchmark problem. 相似文献
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Yuki Kamidaira Hideyuki Kawamura Takuya Kobayashi Yusuke Uchiyama 《Journal of Nuclear Science and Technology》2019,56(8):752-763
Oceanic regional downscaling capability was implemented into Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) developed by Japan Atomic Energy Agency to enable us to predict more realistically the oceanic dispersion of radionuclides at higher spatiotemporal resolutions for broader applications. The system consisted of a double-nested oceanic downscaling circulation model with tidal forcing and an oceanic radionuclide dispersion model. This system was used to comparatively examine downscaling and tidal effects on the dispersion of radionuclides hypothetically released from the Fukushima Daiichi Nuclear Power Plant in the colder season. The simulated dissolved 137Cs distribution was different from that obtained using coarser-resolution models because downscaling enhanced both horizontal and vertical mixing. The suppression of horizontal mixing and the promotion of vertical mixing by tidal forcing synergistically reduced offshore 137Cs transport. In addition, the submesoscale effects strengthened the three-dimensional 137Cs fluctuations by <10 times, while the tidal effects promoted slightly increased the intensity of three-dimensional 137Cs fluctuations by approximately 3%. This indicated that the submesoscale effects substantially surpassed tidal forcing in oceanic mixing in the coastal margin off Fukushima in the colder season. 相似文献
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针对堆芯燃料组件在地震作用下可能发生的结构变形及破坏现象,采用简化方法对燃料组件进行时程分析,计算地震工况下格架所受的碰撞载荷以及应力情况,并将计算值与格架的压塌载荷以及导向管的应力限值进行了比较,从而对堆芯燃料组件的结构完整性进行了评估,为日后堆芯燃料组件结构的抗震性能分析计算提供参考。 相似文献
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FAN Juanjuan 《等离子体科学和技术》2015,17(11):897-903
Determination of the chemical composition of cement and ratio values of clinker plays an important role in cement plants as part of the optimal process control and product quality evaluation. In the present paper, a laboratory laser-induced breakdown spectroscopy (LIBS) apparatus mainly comprising a sealed optical module and an analysis chamber has been designed for possible application in cement plants for on-site quality analysis of cement. Emphasis is placed on the structure and operation of the LIBS apparatus, the sealed optical path, the temperature controlled spectrometer, the sample holder, the proper calibration model established for minimizing the matrix effects, and a correction method proposed for overcoming the ‘drift’ obstacle. Good agreement has been found between the laboratory measurement results from the LIBS method and those from the traditional method. The absolute measurement errors presented here for oxides analysis are within 0.5%, while those of ratio values are in the range of 0.02 to 0.05. According to the obtained results, this laboratory LIBS apparatus is capable of performing reliable and accurate, composition and proximate analysis of cement and is suitable for application in cement plants. 相似文献