“碰撞-辐射”模型在Z箍缩等离子体K壳层线辐射谱分析中的应用

介绍了由K壳层谱线强度比估算等离子体状态参数的"碰撞-辐射"模型的基本原理.详细描述了自行研制的基于该模型的Z箍缩等离子体K壳层线辐射谱分析程序——ZSPEC的基本情况.给出了氖等离子体的计算结果,包括不同电离态离子的相对含量随电子温度的变化曲线和K壳层谱线强度比在"电子密度-电子温度"平面内的等高线分布图.该程序已在"阳"加速器Z箍缩实验结果分析中得到应用,将椭圆晶体谱仪测得的氖等离子体K壳层谱线强度比与ZSPEC程序计算结果相比较,得出在该发实验 关键词： 碰撞-辐射模型 K壳层线辐射谱')" href="#">K壳层线辐射谱 氖气喷气Z箍缩 阳加速器     

神龙一号轫致辐射靶靶区回流离子测量

神龙一号直线感应加速器(LIA)产生的强流高功率的脉冲电子束与X光转换靶作用后可以产生高剂量的X光,同时由于转换靶的被烧蚀破坏在靶面产生回流离子,该回流离子的存在影响到电子束的聚焦。设计了4套法拉第筒及其对应的偏压电路,法拉第筒被放置在神龙一号X光转换靶上游不同位置,分布在电子束轴线两侧,电路设计最高偏压为1 kV;对神龙一号LIA的X光转换靶面产生的回流离子进行了实验测量,分别得到回流正离子密度约在1021/m3,离子运动速度可达2～3 mm/s。计算比较表明,该离子流强度与神龙一号靶前电子束流相差很大,只有电子束流强的0.27%,对神龙一号电子束聚焦不会造成影响。     

Experimental investigation of the relativistic backward wave oscillator with a periodic guiding magnetic field

Experiment is carried out on the accelerator Sinus-700 to investigate the Relativistic Backward Wave Oscillator （RBWO） with a periodic guiding magnetic field. When the strength of the guiding magnetic field, whose period is 4.6 cm, is 0.54 T, a microwave output power of 0.95 GW at 9.1 GHz microwave frequency is achieved. It is shown that the RBWO with a periodic guiding magnetic field is feasible.     

Primary result of ^236U measurement with accelerator mass spectrometry at CIAE

The rare isotope ^236U has a half-life of 2.342（3）×107 years, and is produced principally by thermal neutron capture on ^235U. The isotopic atom ratio of ^236U/^238U depends on the integral thermal neutron flux received by the material of interest. ^236U is potentially useful as a ＂fingerprint＂ for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity. By extracting negative molecular ion UO^- from the uranium oxide target, simulating the ^236U^16O^- beam transport with ^238U^16O^- and ^208Pb2^16O^- pilot molecular ion beam, transporting the ^236U-containing ion beam with a high resolution injection magnet analyzer and electrostatic analyzer system, and finally identifying and detecting ^236U with a time-of-flight detector （TOF）, a method for AMS （Accelerator Mass Spectrometry） measurement of ^236U was established on the HI-13 Accelerator AMS system at China Institute of Atomic Energy.     

Primary result of ~(236)U measurement with accelerator mass spectrometry at CIAE

The rare isotope 236U has a half-life of 2.342(3)×107 years,and is produced principally by thermal neutron capture on 235U.The isotopic atom ratio of 236U/238U depends on the integral thermal neutron flux received by the material of interest.236U is potentially useful as a fingerprint for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity.By extracting negative molecular ion UO- from the uranium oxide target,simulating the 236U16O- beam transport with 238U16O- an...     

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators,due to their compactness and their convenient shape for tuning and coupling,are very attractive for low-β beam acceleration.In this paper,two types of cavities with different geometry have been numerically simulated the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz,β=0.06 beams then the relative electromagnetic parameters and geometric sizes have been compared.It is found that the second type,whose structural design is optimized with the conical stem and shaping drift-tube,can support the better accelerating performance.At the end of the paper,some structural deformation effects on frequency shifts and appropriate solutions have been discussed.     

Field-driven creep motion of a composite domain wall in a Pt/Co/Pt/Co/Pt multilayer wire

We have studied the field-driven motion of a pair of coupled Bloch domain walls in a perpendicular magnetic anisotropy Pt/Co/Pt/Co/Pt multilayer Hall bar. The nucleation of an isolated but coincident pair of walls in the two Co layers, observed by Kerr microscopy, took place at an artificial nucleation site created by Ga⁺ ion irradiation. The average velocity v of the wall motion was calculated from time-resolved magnetotransport measurements at fixed driving field H, where the influence of the extraordinary Hall effect leads to the observation of voltages at the longitudinal resistance probes. We observed a good fit to the scaling relation lnv∝H^−1/4, consistent the motion of a single 1-dimensional wall moving in a 2-dimensional disordered medium in the creep regime: the two walls are coupled together into a 1-dimensional composite object.     

Vortex motion in high-Tc films and a micropattern-induced phase transition

A micropattern-induced transition in the mechanism of vortex motion and vortex mobility is observed in high-T_c thin films. The competition between the anomalous Hall effect and the guidance of vortices by rows of microholes (antidots) lead to a sudden change in the direction of vortex motion that is accompanied by a change in the critical current density and microwave losses. The latter effect demonstrates the difference in vortex mobility in different phases of vortex motion in between and within the rows of antidots.     

Hall’s and Kőnig’s theorem in graphs and hypergraphs

We investigate the relation between Hall’s theorem and K?nig’s theorem in graphs and hypergraphs. In particular, we characterize the graphs satisfying a deficiency version of Hall’s theorem, thereby showing that this class strictly contains all K?nig–Egerváry graphs. Furthermore, we give a generalization of Hall’s theorem to normal hypergraphs.     

A note on Bridgeland Hall algebras

In this note, let 𝒜 be a finitary hereditary abelian category with enough projectives. By using the associativity formula of Hall algebras, we give a new proof of the main theorem in [17 Yanagida, S. (2016). A note on Bridgeland’s Hall algebra of two-periodic complexes. Math. Z. 282(3):973–991.[Crossref], [Web of Science ®] , [Google Scholar]], which states that the Bridgeland Hall algebra of 2-cyclic complexes of projective objects in 𝒜 is isomorphic to the Drinfeld double Hall algebra of 𝒜.