A Source for Multiply-Charged Ions and Acceleration of C, N and O Ions by IPCR Cyclotron

The design and performance of the ion source which is now used in the IPCR variable energy cyclotron are described. The source is of the electron-bombarded hot cathode type having two cylindrical cathodes of tungsten and a water-cooled copper anode containing a replaceable molybdenum slit plate. The arc discharge is established continuously but not pulsed. The source is usually operated very stably under an arc power of 1.5 to 3kW with a gas flow rate of 1 to 2 cc/min. The lifetime of the source is mainly limited by the erosion of the upper tungsten cathode at about 24 hours. At present, C4+, N4+, O4+, N5+ and O5+ ions are accelerated up to 48~100, 56~1100, 70~95, 56~125 and 70~125 MeV respectively, and a few micro-amperes of these ions are extracted from the cyclotron. The vacuum obtainable in the accelerating chamber is usually 2 ~ 4 × 10-6 mHg, and the loss of ion beam by the charge exchange effect is comparatively small. Extracted ion beams are used in several experiments for about 1900 hours in a year.     

Cross-sections and transport properties of F ions in Ar, Kr and Xe

The aim of the current work is to determine with relatively high accuracy the elastic momentum-transfer cross-sections of F⁻ ions in collisions with noble gases Ar, Kr and Xe. We have applied a simple form of momentum-transfer theory (MTT) based on elastic collisions as the first step in order to develop negative fluorine ion/Ar, Kr, Xe elastic momentum-transfer cross-sections based on the available data for reduced mobilities at 300 K as a function of E/N. In our procedure MTT is used only as the initial step to make adjustments and thus save a lot of computation time. However, our final results have been all obtained by exact Monte Carlo (MC) technique that has been well tested and documented. The unfolded cross-sections were validated or further improved by assuring a good agreement between our MC calculated transport data and the available experimental results for reduced mobility and longitudinal diffusion in the range from 1 Td to 500 Td. We have also calculated the net rates of elastic scattering and detachment.     

Electric-dipole,quadrupole, and magnetic-dipole susceptibilities and shielding factors for closed-shell ions of the He,Ne, Ar,Ni (Cu+), Kr,Pb, and Xe isoelectronic sequences

Theoretical values of electric and magnetic susceptibilities (α₁, α₂, χ₁) and shielding factors (γ₁, γ₂, σ₁) calculated in the relativistic random-phase approximation are presented in tabular form for ions with closed 1s, 2p, 3p, 3d, 4p, 4d, and 5p shells. The table includes all ions in these sequences with nuclear charge up to Z = 56 and a representative selection of ions with 56 < Z ? 92.     

Radiative recombination and photoionization cross sections for heavy element impurities in plasmas: II. Ions of Si, Cl, Ar, Ti, Cr, Kr, and Xe

Total cross sections for radiative recombination with an electron for 36 ions of Si, Cl, Ar, Ti, Cr, Kr, and Xe as well as subshell photoionization cross sections are presented. The electron kinetic energy is ?50 keV. The calculations were performed using the relativistic Dirac-Fock method and the results have been included in a database of radiative recombination and photoionization cross sections for the heavy element impurity ions occurring in plasmas. The data are required for modelling fusion and astrophysical plasmas. To obtain the total radiative recombination cross section, calculations have been carried out for ground and all excited electron states up to states with the principal quantum number n = 20. The subshell photoionization cross sections for all states with n ? 12 and orbital momenta ? ? 6 have been fitted by an analytical expression with five fit parameters which are tabulated.     

Generation and Storage of Multiply-Charged Ions within a RF Quadrupole Trap

A three-dimensional rf quadrupole field trap has been designed for generation of multiply-charged ions by successive electron impacts, and for studies of physical processes occurring during charge transfers. Optimum operating conditions have been derived from theoretical considerations, and preliminary experimental results are given. At the end, some limitations and prospects of the quadrupole trap as a tool for physical investigations are briefly discussed.     

Study the Characteristic of the Hot Cathode of High Current Ion Source

The difference of hot cathode operation mode has great influence on the arc discharge of high current ion source. Based on the analysis of the theory of hot filament with two operation modes and combined with ion source experiments, the paper studies the effects of hot filament operation modes on ion source arc discharge.     

用制备色谱法分离氪氙

叙述了通过改变填充5A分子筛色谱柱的载气流速和色谱柱温度,改变氪、氙的保留时间,实现氪、氙分离。分离后,在低温下分别用活性炭收集。结果表明,延长氪、氙色谱柱保留时间的间隔,可提高氪、氙的去污系数;在–80oC低温下,活性炭能很好地收集氪和氙,回收率>95%。     

Investigation of Arc Regulation of Hot Cathode Ion Source with Langmuir Probe

The neutral beam injector (NBI) is one of the main plasma heating methods for nuclear fusion devices. For the hot cathode high current ion source, the arc current and beam current tends to increase during the beam pulse. In order to gets long pulse beam extraction, the arc regulation technology is employed. The Langmuir probes are installed on the experimental advanced superconducting tokamak-NBI ion source, to feedback control the arc discharge and beam extraction. The experimental results show that, the long pulse of 100 s ion beam is extracted with beam energy of 30 keV with arc regulation. More the results are presented in this paper.     

低温下活性炭吸附分离Kr和Xe

研究了低温下活性炭吸附分离Kr和Xe的方法。Kr和Xe混合气在-78 ℃活性炭吸附柱上进行富集,根据Kr、Xe在活性炭柱上脱附条件的差异实现了Kr和Xe的分离。结果表明,Kr和Xe的回收率均大于90%,Kr样品中Xe的去污系数达10⁴以上,Xe样品中Kr的去污系数达10³以上。     

燃料棒芯块中Kr、Xe的低温释放机理

在Wise反冲机理微观模型的基础上,考虑芯块倒角的影响,给出了倒角表面平均反冲效率的计算模型;击出机理参考Olander的理论;由此建立了一个更为精细的裂变气体低温释放微观模型.使用新建模型进行计算的结果显示,倒角表面的平均反冲效率约为圆柱体芯块表面的两倍;当倒角的表面积与圆柱体芯块表面积相比不可忽略时,裂变气体反冲释放份额的计算应考虑倒角的影响.     

Energies, wavelengths, and transition probabilities for Ge-like Kr, Mo, Sn, and Xe ions

Energy levels, wavelengths, transition probabilities, and oscillator strengths have been calculated for Ge-like Kr, Mo, Sn, and Xe ions among the fine-structure levels of terms belonging to the ([Ar] 3d¹⁰)4s²4p², ([Ar] 3d¹⁰)4s 4p³, ([Ar] 3d¹⁰)4s²4p 4d, and ([Ar] 3d¹⁰)4p⁴ configurations. The fully relativistic multiconfiguration Dirac-Fock method, taking both correlations within the n=4 complex and the quantum electrodynamic effects into account, have been used in the calculations. The results are compared with the available experimental and other theoretical results.     

O-离子单电子解离过程的研究

采用交叉束方法，利用兰州大学串列加速器的负离子源提供的4—19kev的O^-与惰性气体靶原子He、Ne、Ar碰撞，通过静电偏转和位置灵敏探测器区分碰撞后中性粒子束和负离子束，测量了不同碰撞系统的中性粒子计数与相应入射负离子计数的比值R（E），讨论了R（E）与入射负离子能量E和靶原子种类的依赖关系。     

Preparation of Ne, Mg, Si, S, and Ar targets by ion implantation into thin carbon foils

The preparation of isotopically pure targets of ²⁰Ne, ²⁴Mg, ²⁸Si, ³²S, and ³⁶Ar by the implantation of 25-70 keV ions into carbon foils is described.     

Energy loss of energetic Ar, Kr, Au and U ions in mylar, aluminum and isobutane

The BigSol Superconducting Solenoid Beam Line at the Texas A&M Superconducting Cyclotron has been used to measure energy losses of ⁴⁰Ar, ⁸⁴Kr, ¹⁹⁷Au and ²³⁸U ions in mylar, aluminum and isobutane at energies ranging from the Bragg peak up to several MeV/nucleon. The experimental data are compared with predictions from the SRIM code. In general experimental data for ⁴⁰Ar and ⁸⁴Kr are in agreement with model predictions whereas differences on the order of 10% are evidenced in some cases for ¹⁹⁷Au and ²³⁸U ions especially at and around the Bragg peak energies.     

利用电离能去除40Ar^2＋对20Ne^＋的干扰

以^40Ar的第一和第二最小电离能之和作为阈值,在GAM400四极质谱计的探测限内以调节轰击电子能量接近于该阈值的方式去除了^40Ar^2＋对^20Ne^＋的干扰。该方法不需要附加样品处理条件,不改变原始样品成份,为Ne的同位素分析工作提供了一种简便快捷的去于扰方法。     

Effects of energy deposition on mechanical properties of sodium borosilicate glass irradiated by three heavy ions: P,Kr, and Xe

Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification;therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young's modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1(60.0% SiO_2, 15.0% B_2O_3, and 25.0% Na_2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively.The hardness and Young's modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young's modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young's modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young's modulus were apparent at approximately 1.2 × 10~(20) keV/cm~3 and 1.8 × 10~(20) keV/cm~3,respectively. The dose dependency of the hardness and Young's modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 10~(22) keV/cm~3 in this work. Therefore, the evolution of hardness and Young's modulus could have been primarily induced by nuclear energy deposition.     

Xe~+离子辐照诱导国产T91及316Ti钢微结构变化研究

对国产T91及316Ti钢进行室温下200keV的Xe~+离子辐照,使用X射线衍射(XRD)、透射电镜(TEM)等检测方法研究不同损伤剂量下辐照对材料相的稳定性和微观结构变化的影响。研究结果表明:T91钢辐照后未发生明显相变,而316Ti发生了γ(FCC)→α(BCC)的马氏体相变,且随辐照损伤剂量的增加,α相含量增加,相变的主要驱动力为辐照离子在辐照层的聚集从而产生的剪切应力;T91钢中的M_(23)C_6颗粒随辐照损伤剂量的增加,非晶化越来越明显,主要是由于辐照粒子的轰击削弱了M_(23)C_6颗粒晶格的稳定性,晶格塌陷成为非晶状态;316Ti钢在较低辐照损伤剂量(4.6dpa)下出现黑斑结构,而在高辐照损伤剂量(37.1dpa)下黑斑结构进一步聚集形成位错环。     

吸附法净化高温气冷堆He载气中Kr、Xe的研究

用椰子壳活性炭吸附剂固定床吸附法去除高温气冷堆He载气中Kr、Xe杂质。获得了Kr、Xe在椰子壳活性炭上的动吸附规律。考察了吸附温度、浓度、流速及床高等因素对保护作用时间、完全饱和时间、吸容量的影响,获得最佳运行参数。结果表明：采用椰子壳活性炭可以除去高温气冷堆He载气中Kr、Xe等有害杂质,满足净化系统的要求。     

85Kr测厚源制备及焊接性能分析

为保证⁸⁵Kr测厚源的密封质量,通过⁸⁵Kr测厚源结构设计、焊接工艺参数优化,制备合格的⁸⁵Kr测厚源。铜管与壳体的连接采用真空钎焊工艺,钎焊温度约900 ℃,时间约30 min;源窗与壳体的连接采用电子束焊工艺,焊接电流7 mA,焊接转速13 mm/s;源后盖与壳体的连接采用激光焊工艺,焊接功率180~185 W,焊接速度2 mm/s。测厚源检验结果表明,所制备的85Kr测厚源,氦质谱检漏结果小于1.0×10^-9 Pa·m³·s^-1,放射性气体检验不超过4 kBq/24 h,符合GB/T 15849—1995中“其他射气检验方法”要求。金相实验结果表明,采用优化参数试样的焊缝中未发现明显的裂纹、未焊透、未熔合等缺陷,最大焊接熔深约0.73 mm。