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| 1 | ORNL-HRIBF 6GHz ECR离子源的最新结果(英文)显示文摘Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source.The emittance of the source was investigated for the first time.The output beam currents of high-charge-states of Ar(q>8)were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter.To investigate possible enhancements with broadband microwave radiation,a'white'Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of~200MHz.The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region.However,the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned off the flat-B region. | Y.Kawai G.D.Alton | 2007 | Chinese Physics C2007，31，S1： | 0 |
| 2 | 宽带微波馈入对于具有常规磁场构型的ECR离子源性能的提高显示文摘As clearly demonstrated at several laboratories,the performances of electron-cyclotron resonance (ECR)ion sources can be enhanced by increasing the physical sizes(volumes)of embedded ECR zones.En- larged ECR zones have been achieved by engineering the central magnetic field region of these sources so they are uniformly-distributed'volumes'in resonance with single-frequency rf power.Alternatively,the number of ECR surfaces in conventional minimum-B geometry sources can be increased by heating their plasmas with multiple,discrete frequency microwave radiation.Broadband rf power offers a simple,low cost and arguably more effective means for increasing the physical sizes of the ECR zones within the latter source type.In this article,theoretical arguments are made in support of the volume effect and the charge-state enhancing ef- fects of broadband microwave radiation(bandwidth:200MHz)plasma heating are demonstrated by comparing the high-charge-states of Ar ion beams,produced by powering a conventional minimum-B geometry,6.4GHz ECR ion source,equipped with a biased disk,with those produced by conventional bandwidth(bandwidth:~1.5MHz)radiation. | G.D.Alton Y.Kawai Y.Liu O.Tarvainen P.Suominen H.Koivisto | 2007 | Chinese Physics C2007，31，S1： | 0 |
| 3 | 受空间电荷效应影响的离子束流从等离子体边界的最佳引出的一阶理论(英文)显示文摘The problem of extracting space-charge-limited ion beams from spherical emission boundaries is analyzed for simple,two electrode,parallel-plate and spherical sector electrode systems by application of Langmuir-Blodgett theory with account taken for the divergent lens effect caused by the aperture in the extraction electrode.Results derived from simulation studies for the three electrode system,designed for use with the Oak Ridge National Laboratory ECR ion source,complement predictions made from elementary analytical theory with or without magnetic field in the extraction region of the source.Under minimum half- angular divergence(minimum emittance)conditions,the plasma emission boundary has an optimum curvature and the perveance,P,(i.e,current density,j+and extraction gap,d),has an optimum value for a given charge- state.From these studies,we find that the optimum perveance for any electrode system can be determined from the Child-Langmuir relation for the parallel-plate electrode system multiplied by a factor,F with value 0.49≤F≤1. | G.D.Alton H.Bilheux | 2007 | Chinese Physics C2007，31，S1： | 0 |
| 4 | 在线同位素分离装置的靶系统设计方法显示文摘产生放射性核束的在线同位素分离装置的靶系统设计是整个装置产生效率的关键环节 .在ORNL的窄高斯分布的离子注入模型的基础上 ,研究了不同的靶的几何形状和尺寸、不同的温度条件、半衰期不同的放射性核素等对释放时间特性的影响 ,这对设计具有快速释放过程的靶系统 ,具有直接的实用价值 .基于德国ZFK关于表面物理的实验测量数据 ,用MonteCarlo统计的方法来模拟放射性核素从靶材料表面到在线离子源的电离室的传输过程 ,对大量的放射性核素 -传输管材料组合 ,和不同尺寸的传输管进行了统计计算 ,从这些统计计算中得到了可用于传输管工程设计的图表和经验公式 . | 张天爵 G.D.Alton | 2002 | 高能物理与核物理2002，26，3： | 0 |
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