A phase-controlled lower hybrid wave （LHW） multi-junction （M J） coupler （3（rows）×4（columns）×4 （subwaveguides）） has been developed in the HT-7 tokamak. Simulations show that it is more effective f...A phase-controlled lower hybrid wave （LHW） multi-junction （M J） coupler （3（rows）×4（columns）×4 （subwaveguides）） has been developed in the HT-7 tokamak. Simulations show that it is more effective for driving plasma current than an ordinary phase-controlled LHW antenna （3（rows）× 12（columns）） （traditional coupler）. The plasm-wave coupling experiments show that the reflection coefficient （RC） is below 10%, implying that the MJ grill can launch the wave into the plasma effectively. The effect of power spectrum launched by the MJ coupler on RC indicates that an optimal condition is requisite for a better coupling in the lower hybrid current drive （LHCD） experiments, Studies indicate that the drive efficiency of the MJ antenna is higher than that of the traditional one, which is mainly ascribed to the discrepancy in impurity concentration, plasma temperature, and spectrum directivity. An improved confinement with an electron internal transport barrier is obtained by LHCD. The analysis shows that the modified negative （low） magnetic shear and the change of radial electric field profile due to LHCD are possible factors responsible for the eITB formation.展开更多
A five-channel polychromator, utilizing high performance interference filters, has been completed for Thomson scattering measurements on HT-7 tokamak. For our instrument, the range of electron temperature varies from ...A five-channel polychromator, utilizing high performance interference filters, has been completed for Thomson scattering measurements on HT-7 tokamak. For our instrument, the range of electron temperature varies from 50 eV to 1.5 keV. According to this, the bandpass of the different interference filters are chosen. Unique features of the polychromator are high throughput, easy alignment, flexibility and compact size when compared with other alternatives. In this article, both the method of designing and the measured transmission curves for the polychromator are given.展开更多
随着移动互联网和物联网的快速发展,越来越多的终端设备接入网络边缘节点,数据量呈现爆炸式增长,其中流媒体数据占比超80%。网络边缘设备需要从数据中心请求数据,导致主干网络流量压力剧增,进而导致数据传输延迟增加,用户服务质量难以...随着移动互联网和物联网的快速发展,越来越多的终端设备接入网络边缘节点,数据量呈现爆炸式增长,其中流媒体数据占比超80%。网络边缘设备需要从数据中心请求数据,导致主干网络流量压力剧增,进而导致数据传输延迟增加,用户服务质量难以得到有效保障。内容分发网络(content distribution networks,CDN)是缓解主干网络压力、提高服务质量的有效手段。CDN将一定区域内用户经常访问的数据缓存在靠近用户的网络边缘节点,从而减少网络带宽压力,降低数据传输时延,提高服务质量。然而,网络数据内容分发,尤其是流媒体处理,对服务器体系结构性能和功耗有着非常严格的要求,而且网络数据内容分发应用具有不同于传统高性能应用的特征。因此,如何设计高能效CDN服务器体系结构成为亟需解决的问题。基于此,本文对CDN应用在传统服务器体系结构上的性能进行全面的测试,包括应用类型、中央处理器(central processing unit,CPU)利用率、分支预测失误率、缓存(Cache)失效率、网络带宽、时延以及片外存储性能等;基于测试结果,分析了CDN应用对体系结构不同于传统高性能计算应用的需求;基于分析结果,对面向CDN应用的体系结构给出了相应的设计建议和优化方向。本文的研究结果对面向未来高能效的CDN服务器体系结构设计具有一定的借鉴意义和实用价值。展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10205015 and 10575104）.Acknowledgement 0ne of the authors, Ding B J, would like to thank the members of HT-7 Team for their cooperation and kindly help.
文摘A phase-controlled lower hybrid wave （LHW） multi-junction （M J） coupler （3（rows）×4（columns）×4 （subwaveguides）） has been developed in the HT-7 tokamak. Simulations show that it is more effective for driving plasma current than an ordinary phase-controlled LHW antenna （3（rows）× 12（columns）） （traditional coupler）. The plasm-wave coupling experiments show that the reflection coefficient （RC） is below 10%, implying that the MJ grill can launch the wave into the plasma effectively. The effect of power spectrum launched by the MJ coupler on RC indicates that an optimal condition is requisite for a better coupling in the lower hybrid current drive （LHCD） experiments, Studies indicate that the drive efficiency of the MJ antenna is higher than that of the traditional one, which is mainly ascribed to the discrepancy in impurity concentration, plasma temperature, and spectrum directivity. An improved confinement with an electron internal transport barrier is obtained by LHCD. The analysis shows that the modified negative （low） magnetic shear and the change of radial electric field profile due to LHCD are possible factors responsible for the eITB formation.
基金The project supported by the National Nature Science Foundation of China(No.10075049 and No.10275068)
文摘A five-channel polychromator, utilizing high performance interference filters, has been completed for Thomson scattering measurements on HT-7 tokamak. For our instrument, the range of electron temperature varies from 50 eV to 1.5 keV. According to this, the bandpass of the different interference filters are chosen. Unique features of the polychromator are high throughput, easy alignment, flexibility and compact size when compared with other alternatives. In this article, both the method of designing and the measured transmission curves for the polychromator are given.
文摘随着移动互联网和物联网的快速发展,越来越多的终端设备接入网络边缘节点,数据量呈现爆炸式增长,其中流媒体数据占比超80%。网络边缘设备需要从数据中心请求数据,导致主干网络流量压力剧增,进而导致数据传输延迟增加,用户服务质量难以得到有效保障。内容分发网络(content distribution networks,CDN)是缓解主干网络压力、提高服务质量的有效手段。CDN将一定区域内用户经常访问的数据缓存在靠近用户的网络边缘节点,从而减少网络带宽压力,降低数据传输时延,提高服务质量。然而,网络数据内容分发,尤其是流媒体处理,对服务器体系结构性能和功耗有着非常严格的要求,而且网络数据内容分发应用具有不同于传统高性能应用的特征。因此,如何设计高能效CDN服务器体系结构成为亟需解决的问题。基于此,本文对CDN应用在传统服务器体系结构上的性能进行全面的测试,包括应用类型、中央处理器(central processing unit,CPU)利用率、分支预测失误率、缓存(Cache)失效率、网络带宽、时延以及片外存储性能等;基于测试结果,分析了CDN应用对体系结构不同于传统高性能计算应用的需求;基于分析结果,对面向CDN应用的体系结构给出了相应的设计建议和优化方向。本文的研究结果对面向未来高能效的CDN服务器体系结构设计具有一定的借鉴意义和实用价值。
