托卡马克LHCD系统的等离子体电流熄灭保护技术

根据实际HT－7托卡马克的实验需要,提出并实现了等离子体电流熄灭保护装置,杜绝了等离子体电流熄灭或在低等离子体电流下,强功率、长脉冲的低杂波对托卡马克装置及低杂波系统的威胁。     

SUNIST球形托卡马克的研究进展

球形托卡马克为聚变能的商业应用提供了一条可能的途径。中国联合球形托卡马克SUNIST以真空室的环向和极向都有绝缘隔缝为结构特征。该装置的主要任务是研究低环径比等离子体的基本特性和等离子体的非感应加热与电流驱动。包括同轴磁螺旋性注入电流启动、电极放电辅助电子回旋波电流启动、电子伯恩斯坦波以及离子高次谐波快波加热与电流驱动。装置已经顺利组装完毕,并安装了磁测量、静电探针和软X射线等基本的诊断系统。目前正处于系统联调阶段。     

球形托卡马克装置SUNIST的建立

2002年建成的SUNIST球形托卡马克装置是中国第1台低环径比(R／α≈1．3)的托卡马克装置，具有氟橡胶交叉密封和电绝缘的结构。该装置主要设计参数为：大半径0．3111，小半径0．23m，自然拉长比1.6，截面中心磁场0．15T和等离子体电流50kA。在初步的欧姆加热实验中已得到了等离子体电流为52kA的可重复放电。     

从低杂波电子相互作用到低杂波离子相互作用的转折密度

在HL-1M托卡马克上,当等离子体密度大于4×10~(13)cm~(-3)时,成功地进行了可重复的低杂波离子加热实验。提出了一个基于离子朗道阻尼的模型来解释这些实验结果。主要考虑了波在等离子体中加热离子的垂直于环向磁场的电场远大于加热电子的平行于环向磁场的电场。在假定低杂波波谱上移后,由所提出的模型得到的从低杂波电子相互作用到低     

从低杂波电子相互作用到低杂波离子相互作用的转折密度(英文)

在HL-1M托卡马克上,当等离子体密度大于4×10~(13)cm~(-3)时,成功地进行了可重复的低杂波离子加热实验。提出了一个基于离子朗道阻尼的模型来解释这些实验结果。主要考虑了波在等离子体中加热离子的垂直于环向磁场的电场远大于加热电子的平行于环向磁场的电场。在假定低杂波波谱上移后,由所提出的模型得到的从低杂波电子相互作用到低杂波离子相互作用的转折密度不但与HL-1M上的实验结果相符合,也与其它托卡马克的实验结果相符合。计算结果表明转折密度随电子离子温度比的变化非常敏感。     

EAST全超导托卡马克等离子体击穿模拟

托卡马克装置的等离子体击穿有两个关键因素：合适的环电压和真空区域尽可能大的零场区。极向场线圈电流放电引起真空室感应涡流的产生,感应涡流对零场的优化、环电压的建立都有着不容忽视的影响。文章在对EAST真空室简化和划分的基础上,求解出真空室上感应涡流在等离子体击穿阶段的分布,对环电压的建立和零场区的变化情况进行了有效模拟。     

SWIP-RFP装置等离子体环电压和电流测量(英文)

介绍SWIP-RFP装置等离子体环电压和环电流的测量方法和测量结果。对RFP环电压模型也作了初步分析,实验中采用单匝线圈测量的环电压很大程度地取决于外电路的电流,这一电压中存在一感应分量,即使考虑了测量环电压的感应分量,RFP等离子体的环电压也要大于环形磁约束系统等离子体的经典电阻环电压,这是反场箍缩等离子体螺旋量守恒的一个重要课题。对与环电压有关的电磁特性也作了一定研究。测量结果表明,SWIP-RFP装置的等离子体电流一般大于60kA,在较好的放电条件下,等离子体电流可以驱动到100kA,等离子体电流最大值时刻的单匝线圈测量的环电压约为250V。这样的结果与其它方式的估算是相对应的。测量结果还揭示了RFP装置大的等离子体电流密度和异常的环电压的存在。     

中国环流器新一号(HL-1M)物理设计

中国环流器新一号(HL-1M)是在中国环流器一号(HL-1)基础上升级改造的托卡马克装置。基于当时世界上受控核聚变研究发展的趋势,经过深入研究和广泛的物理技术论证,确立了关于HL-1改造的主要方向,即去掉原有的厚铜壳,改造真空室,并根据等离子体需要改造电源设备,以便于开展较大规模的辅助加热和无感驱动电流研究。HL-1M装置的主要物理目标是开展兆瓦级功率的辅助加热和低混杂波电流驱动研究。此外,还将通过装置的改进,增大等离子体体积,在更高参数下研究欧姆加热等离子体性质,在自己的装置上获得对未来设计托卡马克装置有用的实验数据库,并为下一代更大托卡马克装置(HL-2)的建造积累经验。同时,利用HL-1实验结果外推和托卡马克实验定标关系,以及数值模拟计算和理论分析,详细地设计了HL-1M的欧姆加热和辅助加热等离子体物理参数。     

低环径比托卡马克堆中等离子体特性及α粒子输运

低环径比托卡马克装置的实验和理论结果已证实它有利于改善MHD稳定性。基于目前等离子体物理,向减小环径比方向外推,初步讨论了低环径比托卡马克堆的物理特征。在自洽的低环径比托卡马克堆参数下,计算了α粒子约束和损失以及不同环径比对α粒子约     

KSTAR托卡马克设计

韩国超导托卡马克（KSTAR）探索性研究项目是韩国国家聚变计划的重点项目，其主要工作是研制能稳态运行的先进超导托卡马克，为具有吸引力的聚变堆建立科学技术基础。该托卡马克的主要参数是，大半径1.8m，小半径0.5m，环向场3．5T，环向场3．5T，等离子体电流2MA，并具有强变形的等离子体横截面和双零偏滤器。最初由极向磁系统提供的脉冲长度为20s，但是通过非感应电流驱动脉冲长度可以增大到300s。等离子体加热和电流驱动系统包括中性束，离子回旋波，低杂波和电子回旋波，它们都可用于灵活的剖面控制。全套诊断设备计划用于等离子体控制和特性计算以及对物理学的了解。该项目已经完成概念设计阶段，进入到工程设计阶段。首次产生等离子体的日期确定在2002年。     

我国东南沿海城市地下建筑氡浓度分布

为了解东南沿海城市地下建筑氡浓度的分布，用固体核径迹法(SSNTD’s)，分别在春、夏、冬3季对沿海7城市地下建筑室内氡浓度进行调查。结果表明，福州具有最高的平均氡浓度，上海的平均氡浓度最低。季节的变化对地下建筑室内氡浓度有影响，各城市氡浓度平均值夏季最高、冬季最低。各城市夏季氡浓度与该城市的年均值的比值与城市中各测点氡浓度之间的离散度有一定的相关性。夏季地下建筑室内氡浓度高的城市，它的平均氡浓度受某些具有高氡水平测点的影响大。     

Fusion Safety Studies in Russia in 1996

The paper seeks to provide a summary report of observations and results of some Russian fusion safety studies performed in 1996. Release of tritium and helium from neutron irradiated beryllium at relatively high neutron fluences has a burst nature. With the growth of the beryllium temperature-increase rate to 90 K/s, the temperature of tritium burst release decreases from 800 to 450–500°C and for helium decreases from 1200 to 500°C. Characterization of carbon and tungsten dust produced in experiments simulating plasma disruptions revealed that dust particle distribution of sizes for graphites and carbon fiber composites has a bimodal nature with maxima in the range of 0.01–0.03 and 2–4 m for composite UAM and in the range of 0.14–0.18 and 2–4 m for graphite MPG-8. Chemical reactivity of beryllium with air was studied as well. A mathematical model for beryllium weight gain under its chemical interaction with air at temperatures of 700–800°C as a function of beryllium porosity, temperature, and interaction duration was developed.     

Trends in computational intelligence in nuclear engineering

Several changes to the focus of Computational Intelligence in Nuclear Engineering have occurred in the past few years. With earlier activities focusing on the development of condition monitoring and diagnostic techniques for current nuclear power plants, recent activities have focused on the implementation of those methods and the development of methods for next generation plants and space reactors. These advanced techniques are expected to become increasingly important as current generation nuclear power plants have their licenses extended to 60 years and next generation reactors are being designed to operate for extended fuel cycles (up to 25 years), with less operator oversight, and especially for nuclear plants operating in severe environments such as space or ice-bound locations.     

Increase in internal friction in uranium with change in temperature

On the basis of the previously described increase in internal friction in uranium during heating, a semiquantitative evaluation was made of the dependence of increase in internal friction on the rate of heating, frequency and amplitude of vibrations. The results of the calculations agree satisfactorily with data obtained experimentally. A study was made of the effect of the initial state of the specimen on the increase in internal friction at the initial stages of heating.     

Temporal changes in vertical distribution of 137Cs in litter and soils in mixed deciduous forests in Fukushima,Japan

Downward migration of ¹³⁷Cs in soils was studied in three mixed deciduous forests c.a. 40 km northwest of the Fukushima Daiichi Nuclear power plant (FDNPP), Japan. We selected three different types of forest regarding to environmental condition such as slope inclinations and snow coverage conditions at the time of deposition. We examined temporal changes in the vertical distribution of ¹³⁷Cs from litter layers to 10 cm soil depth for two years (2.3 to 4.3 years after the FDNPP accident in 2011). At all three study sites, the ¹³⁷Cs in the litter layer had largely migrated to surface soil by 2013. After 2014, about 80% of the ¹³⁷Cs in forest soils (litter layer to 10 cm soil depth) remained within 0–5 cm soil layer. The vertical distribution had not changed substantially since 2014, suggesting that changes to the downward migration rates of ¹³⁷Cs in soils drastically decreased with time. In addition, small amounts of migrating ¹³⁷Cs could not be detected by the present method because there was a large spatial variation in the distribution of soil ¹³⁷Cs. The results showed similar patterns of soil ¹³⁷Cs distribution among the three study sites although there were differences in the environmental conditions.     

固体核径迹研究进展

介绍最近几年固体核径迹研究取得的主要进展，包括：径迹形成机制和探测方法研究固体核径迹在核物理、高能和相对论重离子核反应，原子物理、空间科学、宇宙射线探测、地学、测氡和核孔膜等领域的应用。     

广东省进出口食品中的放射性检验

报道了广东省商检中心放射性检验室开展的广东进出口食品中的放射性检验工作。介绍了检验工作采用仪器的主要性能及应用;给出了分析测量方法和探测下限以及实验的质量保证措施,并给出了检验室测量的广东省几种食品中的放射性含量范围,测量结果与我国食品中放射性活度变化范围大体一致。     

自噬与鼻咽癌放疗研究进展

自噬对鼻咽癌(Nasopharyngeal carcinoma,NPC)具有抑瘤和促瘤双重作用。自噬在NPC发生、发展及转归中起重要作用:低水平、基础自噬有利于细胞的自我保护与新陈代谢,是NPC放、化疗抵抗的重要因素之一;高水平、过度自噬则可导致自噬性细胞死亡,是基于自噬靶点的NPC治疗基础。自噬剂的研发与应用是实现自噬水平调控的关键环节,自噬抑制剂或自噬诱导剂可增敏NPC放、化疗甚至诱导其自噬性细胞死亡,但其作用机理颇为复杂且迄今尚未完全明了。本文着重综述自噬与NPC放疗研究进展,并探讨自噬作为新靶点的NPC治疗前景,尤其X射线作为自噬剂以诱导NPC发生治疗性的自噬性细胞死亡。     

Tritium concentrations in precipitation in Shanghai

Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ranged from 0.68 ± 0.04 to 4.11 ± 0.39 Bq/L, and it showed a decreasing trend compared with historical data; however,the values were slightly higher than the natural background tritium level. Additionally, the tritium concentration shows a seasonal variation: It was higher in autumn and winter and lower in summer and spring. A comparison of concentrations in precipitation in Shanghai and around the Qinshan Nuclear Power Plant reveals no correlation,implying that the nuclear power plant operations may not affect the environment of Shanghai. Thus, the raised tritium concentrations in Shanghai might be due to the effects of monsoons, spring leak, raindrop, or other activities that generate tritium there. Those activities may include chemistry research that uses tritium as a tracer.