New progress on beam availability and reliability of PKU high intensity CW proton ECR ion source

The stability and reliability of an ion source and its beam availability are extremely significant for any accelerator,especially for those high current long term CW operation ones like ADS. Although the first high quality 306-hours continuous wave（CW） operating curve at 50 m A@35 ke V has been successfully obtained with a standard compact 2.45 GHz ECR ion source at Peking University（PKU）, but the uncertainties that caused beam trips before are unacceptable during an accelerator real operation and should be eliminated. Meanwhile, no permission will be given when the beam power is upgraded from 50 m A@35 ke V to 50 m A@50 ke V. To improve the PKU CW proton source quality, several upgrades were done recently. After those improvements, a new long term CW proton beam experiment at 50 m A@50 ke V was carried out in June 2016. The total running time is 300.5 hours, including near 6 hours ion source preparation and 294 hours non-disturb continuous operation. Within the continuous 13 days operation, no beam-off happened, no spark was observed,no beam drop appeared, no interrupting action was needed, and only a few beam fluctuations caused by the air conditional failure occurred. Beam availability and reliability within the 294 hours is 100%. The root-mean-square（RMS） emittance of this 50 m A@50 ke V CW proton beam is about 0.186 π.mm.mrad. A careful inspection of the ion source was done after this long term operation and no obvious damage was found. The restart experimental results obtained after the ion source inspection prove the high repeatability of PKU PMECRIS. In addition, a 130-m A H＋beam was obtained at 50 k V with duty factor of 10%（100 Hz/1 ms） with this source. Details will be presented in this paper.

双撑杆索穹顶施工成形和静力性能试验研究（英文）

目的:提出一种稳定性好、便于张拉施工的双撑杆索穹顶结构,以解决该结构的找力分析问题,并考察其施工方法和静力性能,为工程实践提供参考依据。方法:1.通过节点平衡方程,推导出考虑结构自重时的双撑杆索穹顶结构的预应力分布计算公式;2.通过模型试验,比较采用空中组装和整体提升两种施工方法时,结构的内力和位形变化;3.进行满跨荷载和半跨荷载的加载测试,并与有限元分析结果进行了对比。结论:1.本文所得公式可以准确得到双撑杆索穹顶结构考虑自重后的实际预应力分布。2.该结构适合通过张拉外斜索施加预应力;结合整体提升的施工方法,可以显著降低施工难度,使其更适用于实际工程。3.在外荷载作用下,双撑杆索穹顶结构中脊索和内斜索的内力减小,其他斜索和环索的内力增大。

可恢复功能装配式梁柱中柱节点抗震性能研究（英文）

目的:提出一种震后功能可快速恢复的装配式中柱节点,并建立其设计理论;考察装配式中柱节点的抗震性能及震后修复性能,并提出设计建议。创新点:提出一种可快速恢复震后功能的装配式中柱节点;2.提出装配式中柱节点设计理论,并通过数值手段对其合理性进行校核;3.试验研究考察基础试件的抗震性能及震后修复性能。方法:1.通过理论分析手段建立装配式中柱节点设计理论;2.利用数值模拟手段通过4组8个算例来验证节点设计理论,并对节点抗震性能进行数值研究;3.对基础试件进行低周往复荷载试验研究及修复试验研究,进一步验证设计理论的合理性,并考察节点的抗震性能及震后修复性能。结论:1.提出的设计理论可准确地预测装配式中柱节点的屈服荷载;2.设计合理的装配式中柱节点具有良好的承载性能及滞回特性,可满足结构震后功能修复要求;3.翼缘连接盖板厚度和材性、中间螺栓间距和梁段间隙参数对节点抗震性能影响较大,需合理设置。

Experimental study of the pinned double rectangular tube assembled buckling-restrained brace

In this study, seven pinned double-rectangular tube assembled buckling-restrained brace （DRT-ABRB） specimens were experimentally charaeterised by means of an axial cyclic test. The core member of the specimens was a single flat-plate. Two rectangular tubes were assembled using high strength bolts to form an external restraining member. Each rectangular tube was composed of an external steel channel and a cover plate. A gap or thin rubber filler was set between the core and the external restraining member to form an unbonded layer. The influence of several design parameters on the failure mode and energy dissipation capacity of the ABRB was investigated, including the height of the core wing plate, thickness of the external cover plate, and height of the external channel flange. This experimental study demonstrated that a local pressure-bearing failure at the end of the external member arises when the external cover plate is too thin or if the end construction detail is unreasonable. When the end rotations of the DRT-ABRB were restricted, the hysteretic performance was shown to be superior to that of a pure pinned DRT-ABRB. Finally, all the tested DRT-ABRBs exhibited excellent energy dissipation performance which amply satisfied existing regulation requirements.

Study of radially excited Ds(2^1S0)and Ds(3P)

The unobserved J^P= 0^-radial excitation Ds（2^1S0） is anticipated to have mass 2650 Me V（denoted as Ds（2650））. Study of hadronic production is an important way to identify highly excited states. We study hadronic production of Ds（2650） from higher excited resonances in a3P0 model. Relevant hadronic partial decay widths are found to be very small, which implies it is difficult to observe Ds（2650） in hadronic decays of higher excited resonances. Hadronic decay widths of radially excited Ds（3P） have also been estimated. The total decay widths of four Ds（3P） are large, but the branching ratios in the Ds（2650）η channel are very small, which implies that it seems impossible to observe Ds（2650） in hadronic decays of Ds（3P）. The dominant decay channels of the four Ds（3P） have been pointed out, and D1（2420）, D1（2430）, D＊2（2460）, D（2550）, D（2600）,（1-1D2）D（2750） and D3^（2760） are possible to observe in hadronic production from Ds（3P）.