Investigation of the Ion Energy Transport in the Scrape-Off Layer on the J-TEXT Tokamak Using a Retarding Field Analyzer

Radial profiles of the ion temperature,T_i,have been measured by a double-sided retarding field analyzer(RFA) in the scrape-off layer(SOL) of the J-TEXT tokamak(R = 105 cm,r = 25-29 cm,B_t = 1.8-2.0 T,I_p = 120-180 kA,n_e =(2-2.5) × 10~(19) m~(-3)).Strongly declining T_i profiles in the SOL have been found.The different e-folding lengths,At,of the T_i profiles in two experimental configurations with different magnetic connection lengths,L_c,reveal that a longer L_c results in weaker parallel energy transport and longer At.In similarity with the particle transport across the SOL,At is approximately proportional to the square root of L_c.Additionally,the poloidal asymmetry has been identified with enhanced ion energy transport across the SOL on the low-field side.     

Energy properties and spatial plume profile of ionic liquid ion sources based on an array of porous metal strips

An ionic liquid ion source(ILIS)is a kind of high brightness ion source capable of providing high-speed positive or negative ion beams.This paper presents a miniaturized ILIS based on an array of porous metal strips.The porous emitter array,integrated with seven 10 mm long strips,is fabricated using wire electrical discharge machining(WEDM)combined with electrochemical etching.The assembled ILIS is 30 mm x 30 mm x 17.5 mm in size and weighs less than 25 g.A series of experiments,including an I-V characteristic test,a retarding potential analyzer(RPA)test,and a spatial plume distribution test,have been conducted in vacuo to characterize the performance of the ILIS.Results show that the emitted current is up to about 800 μA and ion transparency is as high as 94％.Besides,RPA curves reveal that the total fragmentation rate of the emitted particles accounts for 48.8％in positive mode and 59.8％in negative mode.Further,with the increase in applied acceleration voltage,the voltage loss rises while the energy efficiency decreases.It is also found that the plume perpendicular to the strips has a higher divergence than the one parallel to the strips.A numerical simulation by COMSOL reveals that the electric field distribution between the two electrodes results in such a spatial plume profile.     

在线硼浓度计在压水堆核电站中的应用

国内压水堆核电站在线硼浓度计使用方法有中子吸收法、滴定法和密度法等。文章介绍了在线硼浓度计的测量原理,及其相应的在线监测硼浓度分析仪在国内压水堆核电站实际应用和维护情况,并分析比较了这几类硼浓度计的优缺点。为核电站在线硼浓度计的选型、使用、检修、维护以及提高在线仪表的可用率提供参考。     

多相介质成分测量中的脉冲幅度分析器

本文叙述了一种用于多相介质成分测量中的脉冲幅度分析器,它接收来自探测器的脉冲序列信号,这些脉冲的幅度分布具有两个峰位,分别对应于γ射线的不同的能量。分析器能将序列中不同幅度的脉冲进行甄别,并输出两路独立的计数脉冲,该分析器电路结构简单,速度快,稳定性好。     

Measurements of Neutron Thermalization Time Constant of Light Water by Pulsed Neutron Method

The thermalization parameters of light water have been measured using a pulsed neutron source and non-l/v absorbers (Cd, Gd and Sm). The pulsed neutron source utilizing the D-D reaction was placed at the center of an effectively infinite system of water poisoned with non-1/v; absorbers. The time dependent capture γ-rays from these absorbers were detected by a Nal(Tl) scintillation counter. The neutron thermalization time constant of light water was determined to be 5.3 ± 0.3,μsec from the difference of the decaying reaction rates of the γ-rays, expressed as the sum of two asymptotical exponential components. The resulting value was larger than that of Möller's experiment (4.1 ± 0.4μsec), but agreed fairly well with the theoretical value of 5.6μsec, calculated by Hoshino based on the Nelkin model. A supplementary experiment was performed using thick neutronic filters of Cd and Ag.     

离线灰分仪新型数据采集系统设计

为适应离线灰分仪数据采集的需要,设计了一套新型的离线灰分仪数据采集系统。该系统用多道取代原有的单道和稳峰器,可以实现自动稳峰,操作简单。数据通信使用串口完成,并设计了完整的通信协议,保证数据传输的安全稳定。上位机软件使用LabVIEW编写而成,可以完成灰分仪的控制。     

Electric Potential in Surface Produced Negative Ion Source with Magnetic Field Increasing Toward a Wall

Electric potential near a wall for plasma with the surface produced negative ions with magnetic field increasing toward a wall is investigated analytically.The potential profile is derived analytically by using a plasma-sheath equation,where negative ions produced on the plasma grid (PG) surface are considered in addition to positive ions and electrons.The potential profile depends on the amount and the temperature of the surface produced negative ions and the profile of the magnetic field.The negative potential peak is formed in the sheath region near the PG surface for the case of strong surface production of negative ions or low temperature negative ions.As the increase rate of the magnetic field near the wall becomes large,the negative potential peak becomes small.     

Analysis and Optimization of Stability of CAS-LIBB Single Ion Microbeam

Single ion microbeam is the most advanced technology which can emit a single ion for precise localization. A single-ion microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering （LIBB）, Chinese Academy of Sciences （CAS）, with a spatial resolutions of about 5 μm. Based on CAS-LIBB microbeam, three key elements affecting the quality of the system are assessed： the size of beam spot, the energy range and the counting accuracy of implanting ions. Various contributions to the ion beam stability, including the ion source, the terminal voltage of electrostatic accelerator and the components in beam pipeline, are discussed. Analysis shows that the improvement of terminal voltage stability is the most important issue for future optimization of CAS-LIBB facility. Some preliminary investigations and project aimed at optimization and development are proposed as well.     

Theoretical Analysis on Effect of Adding Argon to Hydrogen Plasma

An increased of H- ion beam current whenever argon gas is added has been observed.The physics behind argon effect is that in the production of more H atoms, a part of H atoms will be converted to H*2(v＞4) to increase H- density. Increase of nH depends on the rate of added Ar η%, primary filling pressure P, electron density neAr and recombination coefficient γ of H atom.Adding 25% Ar is optimal, although there have been assumed various parameters. Increase of nH depends on decreased recombination coefficient γ, and increased primary filling pressure P. The increase of nH is small when the pressure P ＜ 0.3 Pa. Optimized volume size L/R ～ 2 is optimal for obtaining a maximum Ar effect.     

高速SPI通信在多道能谱仪中的实现

基于在ARM+FPGA多道能谱仪中,ARM与FPGA之间的通信速度对数据采集的实时传输具有重要影响,因此本文将SPI通信应用于两者之间进行数据传输,利用ARM自带SPI接口和FPGA上编写SPI模块实现彼此间高速通信,经过仿真、验证和实际应用测试表明该方法能使仪器正常稳定高速工作,而且可移植性强。     

在加速器质谱仪上测量 14C的虚拟双参数多道分析器系统设计

介绍了基于LabVIEW平台与多功能数据采集卡设计的虚拟双参数多道分析器系统 ,及其在加速器质谱仪上测量14 C双参数谱的应用     

Analysis of products of thymine irradiated by ^18O^8＋ ion beam in N2O saturated aqueous solution

Some methods of capillary gas chromatography,such as GC,GC-mS,GC-FT-IR,are used to analyze the products of thymine irradiated by ^18O^8 ion beam in N2O saturated aqueous solution.From the results of GC-MS the molecular weight of products can be determined,and from the results of GC-FT-IR some molecular structure information of products can be obtained.By this way the products,5,6-Dihydrothymine,5-Hydroxyl-5-Methylhydantoin,5-Hydroxyl-6-Hydrothymine,5-Hydro-6-Hydroxylthymine,5-Hydroxymethyluracil,Trans-Thymine glycol,Cis-Thymine glycol and dimers are dtermined without separation of them from sam,ples.Though these products are as same as those products of thymine irraduiated by γ rays in N2O saturated aqueous solution,the mechanism of thymine irradiated by heavy ion beam in aqueous solution is differrent from that by γ rays.The main products of thymine irradiated by ^18O^8 ion beam in N2O saturated aqueous solution are hydroxyl adducts at 5-6 band of thymine,while the main products of thymine irradiated by γ ray in N2O staurated aqueous solution are dimers of thymine.     

离子束轰击涂层(BDC)对钢材耐海水腐蚀的影响

本文介绍了离子束轰击扩散涂层(BDC)对20~#钢和2Cr13钢耐海水腐蚀的影响。通过人工海水全浸腐蚀实验及电化学性能测试,获得了2Cr13 Cr Ni的表面混层的耐海水腐蚀能力与1Cr18Ni9Ti的耐蚀能力相当的结果。     

75MeV/u￣(12)C离子Bragg曲线及黑色素瘤细胞失活的测量

用双电离室法测定了ＨＩＲＦＬ提供的７５ＭｅＶ／ｕ１２Ｃ离子经不同厚度降能片后的相对剂量，将降能片厚度等效为组织等效材料一水中的深度，得到了碳离子在水介质中的Ｂｒａｇｇ曲线，与计算的Ｂｒａｇｇ曲线进行了比较。同时测定了离子经不同厚度降能片后对黑色素瘤（Ｂ１６）细胞的失活效应，得到了离子束在不同贯穿深度上的Ｂ１６细胞存活数据。     

共振物质的重子化学势和奇异子化学势计算

在高能重离子碰撞统计模型中，根据一定温度下的净重子密度和净奇异子密度计算出共振物质的重子化学势和奇异子化学势，并进一步分析净重子密度和净奇异子密度与重子化学势和奇异子化学势之间的关系。计算结果表明：重子化学势和奇异子化学势均随净重子密度和净奇异子密度的增大而增大，而净重子密度比净奇异子密度变化的影响要大得多。     

Development of Conventional Quadrupole Mass Analyzer for RI Target Analysis and Its Performance

A Knudsen-cell-based quadrupole mass analyzer has been developed for the analysis of a small amount of RI sample. To achieve a high signal/noise ratio, a continuous dynode electron multiplier was installed at the end of the mass filter and was operated in a pulse counting mode. Furthermore, the cylindrical shape molecular trap was set around the mass analyzer to reach high degree of vacuum and to reduce the RI contamination area in the apparatus.

The isotope ratio of ¹³⁵Cs/¹³⁷Cs samples has been measured to demonstrate the performance of the mass analyzer. Taking the advantage of the Knudsen-cell's precise controllability over temperature, the contribution of the isobar ¹³⁷Ba was successfully removed in the mass spectrum of cesium. With samples containing about 0.3μg ¹³⁷Cs and almost the same amount of ¹³⁵Cs, the isotope ratio measurement with the total error of 3% has been achieved. The molecular trap was also shown to be effective to reduce the contamination area in the apparatus.     

箍缩反射离子二极管产生的强流脉冲离子束特性

通过对离子束流密度分布的测量和对被离子束轰击的铜箔不同半径处表面微观形貌的分析,研究了200kV箍缩反射离子二极管产生的离子束特性。结果表明：轴线上离子束流密度最大。     

Focusing characteristics of the relativistic electron beam transmitting in ion channel

Based on the beam–plasma system model established in this paper, the trajectory of the electron beam in the ion channel is studied quantitatively through the envelope equation. Under different initial system parameters, the focusing transmission conditions of the beam in the ion channel are discussed. Then, a series of particle-in-cell simulations are performed, which generally versifies the theoretical results and shows some further details of the focusing behavior of the beam. It is found that the deceleration of some electrons around the focusing point or the beam–plasma interaction at the ion channel boundary will result in the generation of the residual electrons,which forms the electron return current that leads to the new instabilities influencing the focusing characteristics of the beam.     

脉冲离子束流聚焦装置的研制

用小型化的质量分析系统进行脉冲离子束流实验研究时,从真空弧离子源中引出的束流脉冲幅度大、能量低,由于空间电荷效应使脉冲束流发散度很大,使得离子束流成分分析的不确定度增大。为克服在有限的空间范围内脉冲离子束流聚焦的困难,研制了一种新的双限束光阑三膜片透镜离子束流聚焦装置。双限束光阑着重减少束流发射度,三膜片透镜则适合小尺度空间的脉冲束流聚焦。计算机模拟的结果符合这种大脉冲离子束流聚焦的设计思想。磁质谱仪应用该聚焦装置后,发散到质量分析器分析盒上的脉冲离子束流幅值从未加聚焦前的115 mA减少至0.06 mA,脉冲离子束流质量分析的不确定度降低。     

Ti-Mo互扩散界面吸氢同位素效应的离子束分析研究

为探究Ti-Mo互扩散对金属吸氢的影响,本文采用离子束分析方法对Ti-Mo薄膜的膜-基互扩散界面的吸氢同位素（H和D）效应进行了研究。通过氩离子刻蚀减薄的方法有效降低了表面碳、氧杂质对样品吸氢的影响。吸氢结果表明,对于表面洁净的样品,氢化后固相中氢或氘的浓度均沿着深度随钼原子含量的增加而减小。在单一气体吸氢实验中,氢原子浓度减小的趋势较氘原子缓慢;而在氢氘混合气体吸氢实验中,当容器中的氢氘压强比p(H2)∶p(D2)≥05∶1时,固体中氘氢浓度之比随钼浓度的增加而降低,但当p(H2)∶p(D2)<05∶1时,氘氢浓度之比随钼浓度的增加而升高。因此,由于Ti Mo界面的互扩散,吸氢出现了显著的氢同位素效应,钼的存在不利于体系对氢同位素气体的吸收。