Non-Uniformity of Ion Implantation in Direct-Current Plasma Immersion Ion Implantation

A particle-in-cell simulation is developed to study dc plasma immersion ion implantation. Particular attention is paid to the influence of the voltage applied to the target on the ion path, and the ion flux distribution on the target surface. It is found that the potential near the aperture within the plasma region is not the plasma potential, and is impacted by the voltage applied to the implanted target. A curved equipotential contour expands into the plasma region through the aperture and the extent of the expansion depends on the voltage. Ions accelerated by the electric field in the sheath form a beam shape and a flux distribution on the target surface, which are strongly dependent on the applied voltage. The results of the simulations demonstrate the formation mechanism of the grid-shadow effect, which is in agreement with the result observed experimentally.     

Progress in AMS Measurement of 182Hf at CIAE

Accelerator mass spectrometry （AMS） is one of the most promising methods to detect minute amounts of 182Hf. However, the sensitivity of 5×10^-11 for ^182Hf/180Hf obtained previously by the AMS method at China Institute of Atomic Energy （CIAE） cannot meet the requirement of some applications. We present some new improvements of measurement method for AMS measurement of 182Hf at the CIAE HI？13 tandem accelerator system. As a result, a sensitivity of 1.0×10^-11 for 182Hf/180Hf is achieved.     

高性能内锡法Nb_3Sn超导股线生产用Sn-Ti合金的研制

高性能内锡法Nb3Sn超导股线可用于国际热核聚变反应堆(ITER)磁体,股线加工过程中的断线问题是股线制备的关键技术之一.在股线的Sn组元中添加适量的Ti不但能够提高Sn的强度利于股线的长线加工;同时Ti元素的添加还可以提高热处理中Nb3Sn的成相速度,降低晶粒尺寸,提高股线的电磁特性.本文介绍了满足Nb3Sn超导股线制备要求的Sn-Ti合金的制备技术,分析了不同浇铸温度对铸锭的影响,对比了加工中Sn-Ti合金的微观组织变化,为我们制备满足ITER要求的Nb3Sn超导股线提供了重要的保障.     

高能闪光照相密度测量的LEPM方法

研究了利用高能闪光照相方法实现密度分布测量的技术.根据闪光照相投影成像原理,将成像过程中的非线性成像因素看成一个综合性的非线性算子,利用先验测量的方法该非线性算子的响应曲线,利用该曲线校正成像图像得到待测客体的光程分布图像.采用以最小误差为重建准则的代数重建法,从光程分布图像中重建出照相客体的线吸收系数分布.最后利用相对等效质量吸收系数以及客体总质量不变的约束条件,获得照相客体的空间密度分布.在高能闪光照相实验平台上进行了静态客体的密度测量实验,测量的均方根误差约为10%.     

水在激光作用下的强制流动沸腾模型

通过分析影响沸腾的各种因素,结合水的流动特性以及激光在水中按照指数衰减的特点,利用单元差分方法着重分析了整个光斑所在区域过余温度的分布,借助水沸腾状态与过余温度之间的关系,建立了水在激光作用下的强制流动沸腾模型.环行光束被作为主要研究对象,对环行光束进行了数据模拟和实验验证.在实验中采用照相法记录下气团的形态,与模拟沸腾曲线具有较好的一致性.     

某身管的实验模态分析

为了了解某身管的振动情况,对该身管进行了实验模态分析,获得了其固有频率、阻尼比和振型等.此外,对身管进行了有限元模态分析,用于对模态试验的指导,并与试验的结果进行了对比和验证,两者符合很好.     

大学物理理论与现象相结合的教学最佳模式的探索

本文结合教学工作实际指出物理演示实验是大学物理理论与现象相结合的教学最佳模式,在大学物理教学中起着积极的推进作用。针对农业院校学时有限、任务繁重的特点,给出了一种开展物理演示实验教学的新模式。     

Tuning of the cosmic-ray test system of the BESⅢ drift chamber

The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the chamber.The noise performance,drift time and charge measurements,and the scanning of channels were examined specifically.The preliminary results of the test indicate that the whole system works well.     

龙牙百合体细胞胚的诱导及植株再生

以龙牙百合鳞片为外植体，以MS为基本培养，通过添加不同浓度的6-BA，2，4-D，研究了其体细胞胚发生的最佳培养条件，并对体细胞胚的发生过程进行了形态学观察。结果表明：影响龙牙百合体细胞胚发生方式的因素是2，4-D。当2，4-D浓度低于0．5mg／L时，体细胞胚以直接方式发生，起源于鳞片表皮下数层细胞或深层的细胞，依次经过多细胞原胚，球形胚，心形胚，成熟胚等阶段，其形态学发育过程与合子胚相似。当2，4-D浓度适中时，体细胞胚以间接方式发生，起源于愈伤组织内部的胚性细胞团，其形态学发育过程也与合子胚相似；诱导胚性愈伤组织的最适培养基为MS＋0．5mg／L6-BA＋2．0mg／L2，4-D，在分化形成体细胞胚时，需降低或去除2，4-D。     

Pterocarine, a New Diarylheptanoid from Pterocarya tonkinesis, its Cell Cycle Inhibition at G0／G1 Phase and Induction of Apoptosis in HCT-15 and K562 Cells

Pterocarya tonkinesis(Franch.)Dode.(Juglandaceae)forms a typical community ofriverside season rain forest in Xishuangbanna area of Yunnan province1.The same genusplant P.stenoptera C.DC.,has long been used as a traditional Chinese herbal medicine2and P.tonkinesis,itself,is also used as a folk medicine for the treatment of certain cancersin partial area of China.However,no report had so far been seen on the chemicalconstituents and their biological activities of the title plant yet.In the …