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作为先进压水堆核电站关键技术研究项目之一,参照西屋电气公司和法马通公司的相关技术,研制了线功率密度保护的物理模型.通过限制线功率密度,可以限制燃料芯块的温度.在保证安全运行的基础上,能更准确地描述堆芯的运行状况,提供更大的灵活性.本文叙述了线功率密度保护的基本原理和物理模型. 相似文献
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小射野条件下60Coγ射线及6-MV X射线在非均匀介质中的剂量特性研究 总被引:1,自引:1,他引:0
用蒙特卡罗应用程序EGSnrc模拟计算了60Coγ射线、6-MV的点源光子束在有限宽非均匀模体中,不同射野条件下中心轴上的剂量分布情况,利用剂量扰动因子(Dose perturbation factor,DPF)定量研究了剂量增强或减弱效应的强度.DPF即不均匀介质模体中某点的剂量与均匀水模体中同一空间位置点处的剂量值之比.模拟结果表明,剂量扰动效应的强弱程度取决于多种因素,如射线的能量、射野的尺寸和入射介质的尺寸.另外,无论是在骨等效介质中,还是在肺等效介质中,剂量增强或减弱效应随射野尺寸的变化并不是线性的. 相似文献
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聚变电站中工程能量增益与质量功率密度对发电成本的影响 总被引:2,自引:2,他引:0
从经济弹性角度详细分析了聚变电站中工程能量增益与堆体质量功率密度对发电成本的影响。由发电成本对工程能量增益与堆体质量功率密度的函数关系,导出了发电成本对工程能量增益与堆体质量功率密度的“弹性系数”,并由此进行发电成本对工程能量增益与堆体质量功率密度的敏感性分析。分析表明,工程能量增益或堆体质量功率密度越大,发电成本对它们的敏感性越差。 相似文献
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介绍了高温气冷堆TRISO型的包覆燃料颗粒及球形燃料元件的结构特点及其安全原理.高温气冷堆具有低功率密度特点和负温度反应性特点,其与球形燃料元件有安全循环关系,实现了高温气冷堆固有循环安全特性. 相似文献
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物理学家利用高能粒子加速器进行了多方面的研究,但高能粒子加速器庞大且耗资巨大。随着超短超强激光的发展,现在的激光的功率密度可达到10^22W/cm^2。许多实验室利用不同功率密度的激光与固体靶、薄膜靶及气体等相互作用,进行加速产生高能粒子的研究。其中,利用超短超强激光与薄膜薄相互作用加速产生质子是一重要的研究课题,利用超热电子加速产生超热电子, 相似文献
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研究基于简单解析表达式的电子背散射系数与入射电子能量、介质厚度和能损的关系及其对电子束辐射加工的影响,考虑到入射电子在多层介质之间反复的穿透和背散射,编制了ED410程序,计算了不同补底材料和不同入射电子能量下能量沉积的深度分布和剂量因子,利用补底要 背散射抬高接近补底界面处的剂量,较大地改善了辐射加工的均匀性。 相似文献
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固体径迹探测器测量反应堆功率研究 总被引:2,自引:1,他引:1
在零功率反应堆上利用固体径迹探测器直接测量燃料元件内的裂变率,可得到反应堆的功率。同时测量反应堆某位置的热中子通量密度,继而可得到单位功率的热中子通量密度。因此,通过测量该点的任何热中子通量密度即可得到反应堆的运行功率。该方法可以减少与能谱测量有关的修正工作。由于辐照所需的中子通量密度低、时间短,因此与活化法等相比具有明显的优点。 相似文献
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Ion parameters in electron cyclotron resonance (ECR) microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressure and microwave power on the ion temperature and density were analyzed. The spatial distribution of the ion parameters was also investigated by the ion sensitive probes with a tunable radial depth installed on different probe windows along the chamber axis. Results showed that the ion density measured by the ion sensitive probe was in good agreement with the electron density measured by the double Langmuir probe. The influence of gas pressure on the ion parameters was stronger than that of microwave power. With the increase in working pressure, the ion temperature decreased monotonously with a decreasing rate larger than that at higher pressure. The ion density first increased to a peak (42.3?1010cm-3) at 1 Pa and then decreased. The ion temperature and density increased little with the increase in the microwave power from 400 W to 800 W. The plasma far away from the resonant point is found to be radially uniform. 相似文献
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Wenjin ZHANG 《等离子体科学和技术》2022,24(2):25403
The coaxial surface wave linear plasma with preeminent axial uniformity is developed with the 2.45 GHz microwave generator. By optical emission spectroscopy, parameters of the argon linear plasma with a length over 600 mm are diagnosed under gas pressure of 30 and 50 Pa and different microwave powers. The spectral lines of argon and Hβ (486.1 nm) atoms in excited state are observed for estimating electron excitation temperature and electron density. Spectrum bands in 305–310 nm of diatomic OH (${{\rm{A}}}^{2}{{\rm{\Sigma }}}^{+}-{{\rm{X}}}^{2}{{\rm{\Pi }}}_{{\rm{i}}}$) radicals are used to determine the molecule rotational temperature. Finally, the axial uniformity of electron density and electron excitation temperature are analyzed emphatically under various conditions. The results prove the distinct optimization of compensation from dual powers input, which can narrow the uniform coefficient of electron density and electron excitation temperature by around 40% and 22% respectively. With the microwave power increasing, the axial uniformity of both electron density and electron excitation temperature performs better. Nevertheless, the fluctuation of electron density along the axial direction appeared with higher gas pressure. The axial uniformity of coaxial surface wave linear plasma could be controlled by pressure and power for a better utilization in material processing. 相似文献
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Plasma filling can dramatically improve the performance of high power microwave devices.The characteristics of high-power microwave propagation along plasma filled waveguides in an axial magnetic field are analyzed in this paper,and the ponderomotive force effect of high power microwave is taken into consideration.Theoretical analysis and preliminary numerical calculations are performed.The analyses show that the ponderomotive effect would change the plasma density,distribution of microwave field intensity,and dispersion of wave propagation.The higher the microwave power,the stronger the ponderomotive effect.In different magnetic fields,the ponderomotive effect is different. 相似文献
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To develop a larger in-line plasma enhanced chemical vapor deposition(PECVD) device, the length of the linear microwave plasma source needs to be increased to 1550 mm. This paper proposes a solution to the problem of plasma inhomogeneity caused by increasing device length.Based on the COMSOL Multiphysics, a multi-physics field coupling model for in-line PECVD device is developed and validated. The effects of microwave power, chamber pressure, and magnetic flux density on the plasma distribution are investigated, respectively, and their corresponding optimized values are obtained. This paper also presents a new strategy to optimize the wafer position to achieve the balance between deposition rate and film quality. Numerical results have indicated that increasing microwave power and magnetic flux density or decreasing chamber pressure all play positive roles in improving plasma homogeneity, and among them, the microwave power is the most decisive influencing factor. It is found that the plasma homogeneity is optimal under the condition of microwave power at 2000 W, chamber pressure at15 Pa, and magnetic field strength at 45 mT. The relative deviation is within-3.7% to 3.9%,which fully satisfies the process requirements of the equipment. The best position for the wafer is88 mm from the copper antenna. The results are very valuable for improving the quality of the in-line PECVD device. 相似文献
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Kang AN Liangxian CHEN Jinlong LIU Yun ZHAO Xiongbo YAN Chenyi HUA Jianchao GUO Junjun WEI Lifu HEI Chengming LI Fanxiu LU 《等离子体科学和技术》2017,19(9):95505
The effect of the substrate holder feature dimensions on plasma density(ne), power density(Qmw) and gas temperature(T) of a discharge marginal plasma(a plasma caused by marginal discharge) and homogeneous plasma were investigated for the microwave plasma chemical vapor deposition process. Our simulations show that decreasing the dimensions of the substrate holder in a radical direction and increasing its dimension in the direction of the axis helps to produce marginally inhomogeneous plasma. When the marginal discharge appears, the maximum plasma density and power density appear at the edge of the substrate. The gas temperature increases until a marginally inhomogeneous plasma develops. The marginally inhomogeneous plasma can be avoided using a movable substrate holder that can tune the plasma density, power density and gas temperature. It can also ensure that the power density and electron density are as high as possible with uniform distribution of plasma. Moreover, both inhomogeneous and homogeneous diamond films were prepared using a new substrate holder with a diameter of 30 mm. The observation of inhomogeneous diamond films indicates that the marginal discharge can limit the deposition rate in the central part of the diamond film. The successfully produced homogeneous diamond films show that by using a substrate holder it is possible to deposit diamond film at 7.2 μm h~(–1)at 2.5 kW microwave power. 相似文献
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阐明核电站流出物监测仪的校准方法和初级校准与次级准的转换关系,并就这种方法的合理性和可靠性以及传递误差进行了简单的讨论。 相似文献