994 resultados para 7038-401
Resumo:
The aim of this paper is to investigate the mechanism of small scale sand-wave migration. According to the environmental characteristic of the north gulf of South China Sea, a quasi-3D mechanics model has been built for simulating the small scale sand wave migration. The calculation results are shown to be consistent with the observed data in the trough of sand ridge. Considering the effect of environmental actions and sand wave features, we develop an effective formula to predict sand-wave migration. It is indicated that the physical models should be used to predict the migration of the small scale sand-wave, which is rarely dominated by wave activity.
Resumo:
A high current RFQ (radio frequency quadrupole) is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is air important parameter when designing a 4-rod RFQ cavity, it reflects the RF efficiency of the cavity, and has a direct influence on the cost of the structure. Voltage distribution of a RFQ cavity has an effect on beam transmission, and particles would be lost if the actual voltage distribution is not as what, it should be. The influence of cell length, stern thickness and height on Shunt impedance and voltage distribution have been studied, in particular the effect of projecting electrodes has been investigated in detail.
Resumo:
本工作研究了四种不同形状和尺寸的石英管对1100eV、1300eV、1500eV三种能量电子束的导向作用，并把四种实验结果进行了分析对比。四种石英管分别为等径圆柱形弯曲管、等径圆柱形直管、直锥形管以及弯曲锥形管，它们的内径均在毫米量级。实验中利用一个位置灵敏法拉第筒对从石英管出射的电子束进行探测，获得从管道中出射的电子束流强度在位置灵敏法拉第筒各道上的强弱分布，其结果显示宏观尺寸石英管对电子束存在导向作用。对于等径圆柱形石英管，入射电子束流的强度越强，其导向作用越明显；然而对于锥形管，导向作用并不明显，且不随入射电子束流强度增加有明显的变化。此外，实验结果在一定程度上显示出石英管对中低能电子束的导向能力并不取决于管的形状。石英管导向能力与管的尺寸、形状及材料之间的关系还有待进一步的研究
Resumo:
本人建立了一台塑料闪烁体β射线望远镜，该望远镜由工作在符合状态的ΔE探测器和E探测器构成。ΔE探测器由ST-401型塑料闪烁体薄片（Φ 25 * 0.5）构成，用来甄别掉γ射线。E探测器由ST-401型塑料闪烁体（Φ 70 * 70，异形）构成，在跟ΔE探测器符合的条件下，用来测量β谱。光电倍增管均采用GDB-50L型。用该望远镜测量了~(207)Bi 991KeV内转换电子谱，在没有扣除电子到达E探测器闪烁体前Ni窗、E闪烁体和空气对峰的展宽的条件下，主峰分辨为38%。作为对β连续谱测量和处理方法的检验，测量了~(90)Sr-~(90)Y源的β连续谱，并且对该谱用迭代的“展开法”进行了处理。另一方面，本文还利用费米球模型，对重离子核反应类弹产物动量分布宽度进行了计算
