Influence of high-intensity pulsed ion beams irradiation on oxidation behavior of 316L stainless steel at 700℃

316L stainless steel samples, as a widespread used material, were irradiated with HIPIB at the beam parameters of ion energy 300 keV, current density 100, 200 and 300 A/cm2, shot number 10 and pulse duration 75 ns. The surface morphology and the phase structure in the near surface region of original and treated samples were analyzed with scanning electron microscopy (SEM) and X-ray diffractometry (XRD). It is shown that the HIPIB irradiation can smooth the surface of the samples, and the preferred orientation is present in the surface layer of irradiated coupons. The influence of HIPIB irradiation on the oxidation behavior of 316L stainless steel at 700℃for up to 100 h was investigated. Electron probe microanalysis (EPMA) was used to study the distribution of elements in the oxidation products. It is found that the oxidation behavior of the irradiated coupons depends greatly on the ion current density of HIPIB. HIPIB irradiation with ion current density of 100 A/cm2 slightly reduces the oxidation rate with respect to the unirradiated coupon. The improvement of the oxidation resistance can be attributed to more oxide of Cr that forms on the surface of the irradiated coupons. In contrast, HIPIB irradiation with ion current density of 200 or 300 A/cm2 is proved to be detrimental, causing a higher oxidation rate.

Numerical study on the thermo-stress of ZrO_2 thermal barrier coatings by high-intensity pulsed ion beam irradiation

This paper studies numerically the thermo-mechanical effects of ZrO2 thermal barrier coatings （TBCs） irradiated by a high-intensity pulsed ion beam in consideration of the surface structure. Taking the deposited energy of ion beams in TBCs as the source term in the thermal conduction equation, the distribution of temperature in TBCs was simulated. Then, based on the distribution, the evolution of thermal stress was calculated by the finite element method. The results show that tensile radial stress formed at the valley of TBC surfaces after irradiation by HIPIB. Therefore, if cracks happen, they must be at valleys instead of peaks. As for the stress waves, no matter whether through peak or valley position, tensile and compressive stresses are present alternately inside TBCs along the depth direction, and the strength of stress decreases with time.

The Effect of Intensity Pulsed Ion Beam Irradiation on Wear Resistance of High-speed Steel

The structural and phase transformations occurring in the near-surface layers of pre-quenched W6Mo5Cr4V2 high-speed steel (HSS) subjected to intensity pulsed ion beam (IPIB) melting have been investigated. The effect of IPIB irradiation on wear resistance of the HSS has also been studied. The IPIB consists mainly of Cn+(30%)^0 H+(70%), with a high beam current density of 80A/cm2, acceleration voltage of 250kV, pulse duration of 70 ns. Samples were bombarded with 1, 3, 5 pulses respectively. It has been revealed that after IPIB irradiation the initial martensite in the near-surface layer of HSS changed into austenite and produced residual stresses by using electron microscopy and X-ray diffraction. Redistribution and interlace of dislocations in the irradiated samples were generated under the impact of shock wave. With increasing pulse times gradual liquid-phase dissolution of M6C carbide particles occurs in the near-surface layer and produces nanocrystalline MC. This process results in the decrease of martensite crystal (a-phase) and increase of austenite (y-phase) content and the dispersed carbide. Wear resistance of the HSS is improved by a factor of 2, which is explained by the formation of metastable phases such nanocrystal and residual stresses and the redistribution and interlace of dislocations.

Numerical Study on the Two-Dimensional Temperature Fields of Titanium/Aluminum Double-Layer Target Irradiated by High-Intensity Pulsed Ion Beam

Interaction between high-intensity pulsed ion beam （HIPIB） and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with the deposited energy in the target taken as source term, were derived and solved by finite differential method. As a result, the two-dimensional spatial and temporal evolution profiles of temperature were obtained for a titanium/aluminum double-layer target irradiated by a pulse of HIPIB. The effects of ion beam current density on the phase state of the target materials near the film and substrate interface were analyzed. Both titanium and aluminum were melted near the interface after a shot when the ion beam current density fell in the range of 100 A/cm2 to 200 A/cm2.

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam(IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes(MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450(active MID) and TEMP-4M(passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.

Hydrodynamic Effects on Surface Morphology Evolution of Titanium Alloy under Intense Pulsed Ion Beam Irradiation

The hydrodynamic effects of molten surface of titanium alloy on the morphology evolution by intense pulsed ion beam （IPIB） irradiation are studied. It is experimentally revealed that under irradiation of IPIB pulses, the surface morphology of titanium alloy in a spatial scale of μm exhibits an obvious smoothening trend. The mechanism of this phenomenon is explained by the mass transfer caused by the surface tension of molten metal. Hydrodynamic simulation with a combination of the finite element method and the level set method reveals that the change in curvature on the molten surface leads to uneven distribution of surface tension. Mass transfer is caused by the relief of surface tension, and meanwhile a flattening trend in the surface morphology evolution is achieved.

Significant friction reduction of high-intensity pulsed ion beam irradiated WC-Ni against graphite under water lubrication

Two types of commercial WC-Ni samples were irradiated with the High-intensity pulsed ion beam(HIPIB).Both the surface characteristics and tribo-characteristics of the non-irradiated and irradiated WC-Ni samples,sliding against graphite under water lubrication,were compared.Quite low steady friction coefficients(approximately of 0.02) of the irradiated WC-Ni were observed.The surface topographies and components were investigated.The quite low friction of the irradiated WC-Ni samples was ascribed to the higher fluid retention capability of the latter and the tribofilm formed during sliding.

Progress in particle-beam-driven inertial fusion research: Activities in Japan

Research activities in Japan relevant to particle beam inertial fusion are briefly reviewed.These activities can be ascended to the 1980s.During the past three decades,significant progress in particle beam fusion,pulsed power systems,accelerator schemes for intense beams,target physics,and high-energy-density physics research has been made by a number of research groups at universities and accelerator facilities in Japan.High-flux ions have been extracted from laser ablation plasmas.Controllability of the ion velocity distribution in the plasma by an axial magnetic and/or electric field has realized a stable high-flux low-emittance beam injector.Beam dynamics have been studied both theoretically and experimentally.The efforts have been concentrated on the beam behavior during the final compression stage of intense beam accelerators.A novel accelerator scheme based on a repetitive induction modulator has been proposed as a cost-effective particle-beam driver scheme.Beam-plasma interaction and pulse-powered plasma experiments have been investigated as relevant studies of particle beam inertial fusion.An irradiation method to mitigate the instability in imploding target has been proposed using oscillating heavy-ion beams.The new irradiation method has reopened the exploration of direct drive scheme of particle beam fusion.

High Current and High Intensity Ion Beam Sources and Their Technological Applications

High-current ion beams have become a powerful tool for improving the surface properties of different materials.The prospects of wide commercial use of such beams for material treatment is not only due to the possibility of improving their properties,but,also for economic expediency.To achieve a high throughput and reduce the cost on ion beam material treatment,ion beams of high average and pulsed power are necessary.This paper gives an overview of work on generation of pulsed and repetitively pulsed beams of accelerated ions with currents ranging from fractions of an ampere to several tens of kA and with pulse duration from several tens of nanoseconds to several hundreds of microseconds.A number of different methods of materials surface properties modification using high power and intense ion beam and plasma are considered.

用强流脉冲离子束(HIPIB)方法在玻璃表面制备ITO膜

强流脉冲离子束 (HIPIB)方法以新的成膜机理通过高强度 (约 10 8W /cm2 ) ,脉冲 (约 70ns)离子束照射到ITO陶瓷靶材上产生的高密度、高温二次等离子体快速地沉积到室温玻璃基片上成功地制得ITO薄膜。经一次脉冲发射即可制得约 6 5nm厚的膜。通过原子力显微镜 (AFM)图象分析膜的表面形貌 ,膜的平整性与膜厚有直接关系 。

HIPIB辐照处理对316L不锈钢耐磨性的改善

利用强流脉冲离子束(HIPIB)对316L不锈钢进行了表面辐照处理,研究了HIPIB辐照对316L表面摩擦磨损性能的影响。实验结果表明,HIPIB辐照处理后,在深度达50μm以上范围内316L的显微硬度提高,表面滑动摩擦系数降低,耐磨性得到显著改善。采用扫描电子显微镜(SEM)观察辐照前后试样的表面形貌;用X射线衍射(XRD)分析辐照前后试样表面层相结构的变化。结果发现,HIPIB辐照使试样表面光滑化,且表面层产生择优取向。HIPIB辐照引起的强大应力和冲击波使材料发生了明显的塑性变形,不仅导致“形变织构”出现,并且产生大量的位错等缺陷,形成稳定的网络分布,从而强化了316L不锈钢表面层。

Design study of a radio-frequency quadrupole for high-intensity beams

The Rare isotope Accelerator Of Newness（RAON） heavy-ion accelerator has been designed for the Rare Isotope Science Project（RISP） in Korea. The RAON will produce heavy-ion beams from 660-MeV-proton to200-MeV/u-uranium with continuous wave（CW） power of 400 k W to support research in various scientific fields.Its system consists of an ECR ion source, LEBTs with 10 ke V/u, CW RFQ accelerator with 81.25 MHz and 500 ke V/u, a MEBT system, and a SC linac. In detail, the driver linac system consists of a Quarter Wave Resonator（QWR） section with 81.25 MHz and a Half Wave Resonator（HWR） section with 162.5 MHz, Linac-1, and a Spoke Cavity section with 325 MHz, Linac-2. These linacs have been designed to optimize the beam parameters to meet the required design goals. At the same time, a light-heavy ion accelerator with high-intensity beam, such as proton,deuteron, and helium beams, is required for experiments. In this paper, we present the design study of the high intensity RFQ for a deuteron beam with energies from 30 ke V/u to 1.5 MeV/u and currents in the m A range. This system is composed of an Penning Ionization Gauge ion source, short LEBT with a RF deflector, and shared SC Linac. In order to increase acceleration efficiency in a short length with low cost, the 2nd harmonic of 162.5 MHz is applied as the operation frequency in the D^＋RFQ design. The D^＋RFQ is designed with 4.97 m, 1.52 bravery factor. Since it operates with 2nd harmonic frequency, the beam should be 50% of the duty factor while the cavity should be operated in CW mode, to protect the downstream linac system. We focus on avoiding emittance growth by the space-charge effect and optimizing the RFQ to achieve a high transmission and low emittance growth. Both the RFQ beam dynamics study and RFQ cavity design study for two and three dimensions will be discussed.

Two-dimensional numerical research on effects of titanium target bombarded by TEMPⅡ accelerator

Two-dimensional numerical research has been carried out on the ablation effects of titanium target irradiated by intense pulsed ion beam （IPIB） generated by TEMP Ⅱ accelerator. Temporal and spatial evolution of the ablation process of the target during a pulse time has been simulated. We have come to the conclusion that the melting and evaporating process begin from the surface and the target is ablated layer by layer when the target is irradiated by the IPIB. Meanwhile, we also obtained the result that the average ablation velocity in target central region is about 10 m/s, which is far less than the ejection velocity of the plume plasma formed by irradiation. Different effects have been compared to the different ratio of the ions and different energy density of IPIB while the target is irradiated by pulsed beams.

Numerical Research on Plasma Generation and Expansion into Vacuum

Energy deposition of intense pulsed ion beam （IPIB） on the Ti target based on the 2D model of IPIB density has been simulated by the Monte Carlo （MC） method. Taking the deposited energy as the thermal source, we have established the ablation model of the target and calculated the spatial and temporal evolution of the ablation shape of the Ti target irradiated by IPIB with different energy densities. We have also established the ejection model of the hydrodynamic equations related to the ablation shape of the target by using the ablation results as the initial conditions of plasma formed by IPIB irradiation. The spatially and temporally evoluted profiles of the plasma pressure and mass density are calculated.

高能束表面改性技术在航空领域的应用

高能束表面改性适用于各种金属和合金,能够显著提升材料表面硬度、耐磨、耐蚀等性能指标,是航空部件实现性能提升的有效手段之一。本文总结了6种高能束表面改性技术的基本原理、设备构成和改性应用,其中激光相变硬化通过马氏体相变强化金属材料表面;激光熔覆通过选择不同粉末实现表面修复和表面性能提升,重点在于控制裂纹缺陷;激光冲击强化可有效解决航空发动机部件高周疲劳断裂问题;强流脉冲电子束和强流脉冲离子束一方面需要提高设备的性能和运行稳定性,另一方面要针对航空部件应用开展深入研究;而离子束辅助沉积则可以通过制备固体润滑涂层实现对微动磨损的有效防护。最后,提出对高能束表面改性机理深入研究、发展专业化智能化装备和实现多种束源复合与集成的发展方向。

基于强流脉冲离子束的中子辐照模拟装置及评价技术

依据高能原子辐照与中子辐照的初级离位原子(PKA)能谱相似性,基于TEMP-6M型强流脉冲离子束(HIPIB)系统,研发了一种中子辐照模拟装置,该装置以磁绝缘离子二极管伴生的强流脉冲二次电子束流实现0.1 MeV以上高能离子的高效率中和,获得动能为0.1~1 MeV、脉冲宽度为120~160 ns、脉冲辐照剂量为1012~10^(15)n/cm^(2)的强流脉冲原子或混合束,原子占比为85%~100%。通过辐照缺陷原位差热分析方法,快速确定材料缺陷数量、密度及dpa损伤速率等抗中子辐照性能评价指标。以核级AISI 304奥氏体不锈钢为例,计算PKA相似性定标曲线,采用220~280 keV的C原子等效1.8~2.3 MeV中子进行辐照模拟,调节名义束流能量密度0.5~4 J/cm^(2),实测辐照剂量范围为0.46×10^(13)~8.55×10^(13)n/cm^(2),热分析确定Frenkel缺陷密度为1.99×10^(16)~2.90×10^(17)/cm^(2),外推预测奥氏体不锈钢在1021n/cm^(2)中子剂量条件下的辐照损伤为500 dpa量级,适用于核电厂结构材料60年服役寿期评价需求。

高功率环境下多丝靶设计及运行考虑

多丝靶被广泛用于束流截面测量,但是常常因为束流功率沉积导致丝被损坏。为了研究不同束流参数以及丝靶设计与丝上温度和丝变形之间的关联,开发了基于后向欧拉法的自适应步长多丝靶温度数值模拟程序,并在离子源平台上开展了由温度导致的多丝靶变形实验。模拟和实验表明:在缺失恒定张力的情况下,温度是导致丝变形的主因。基于我们的模拟计算、实验验证以及操作经验,在丝温度低于1 300 K的情况下,拉丝采用锡焊固定的方式,其结构简单成本低;在高于1 300 K的情况下,采用弹簧张力的固定方式,可以提供恒定的张力,避免丝变形。

Xe^(23+)离子束轰击低温工况下的无氧铜表面解吸性能研究

强流重离子加速器运行时产生动态真空效应引起束流寿命缩短,需安装无氧铜束流准直器来降低该效应。为探究无氧铜材料在离子束轰击下的解吸性能,本工作设计并研制了满足低温工况的解吸率测试装置,在兰州重离子加速器国家实验室利用Xe^(23+)离子束完成了无氧铜温度在4.2 K、20 K、77 K和300 K,以及束流能量为0.58 MeV/u、0.96 MeV/u和1.3 MeV/u的在束试验。结果表明,离子束轰击无氧铜表面时解吸出最多的分子为H_(2),其次分别为H2O、CO、CO_(2)、Ar和O_(2);当温度为4.2 K、束流能量为0.58 MeV/u时无氧铜解吸出H2的比例为87.74%。在同一能量下,随着无氧铜表面温度的升高,解吸率呈增加趋势,能量为0.58 MeV/u时,4.2 K下无氧铜的解吸率仅为25 mol/ion,小于300 K时的600 mol/ion,表明温度越高其解吸产额越大。在同一温度下,随着束流能量的升高无氧铜表面解吸率增加,但增加趋势逐渐减缓,解吸产额趋向饱和。

强流脉冲离子束辐照W6Mo5Cr4V2高速钢表面改性研究

利用强流脉冲离子束(HIPIB)技术对W6Mo5Cr4V2高速钢进行表面辐照处理.HIPIB主要由Cn+(70％)和H+(30％)组成,束流密度为160 A/cm2,加速电压为250 kV,脉冲宽度为80-100 ns,能流密度为3-4 J/cm2,脉冲次数分别为1,3和5次.利用XRD,SEM和EPMA研究了HIPIB辐照处理前后该高速钢表面层结构和成分的变化,结果表明,HIPIB辐照处理使该高速钢表面层发生由马氏体α’-Fe向奥氏体γ-Fe转变,其表面产生许多火山口状熔坑,熔坑中心处富含离子束元素成分,熔坑的形成可以用“雨滴”模型进行解释.由于HIPIB辐照压缩波的影响,处理后在深度达200μm左右的范围内该高速钢的显微硬度提高,表面层耐磨性能提高近2倍,而且耐腐蚀性能也有所提高.

用于模拟X射线热-力学效应的高功率脉冲离子束研究进展

计算了与黑体谱 1keVX射线在材料中产生的应力波和冲量相当的质子束参数 ;给出了箍缩型二极管产生离子束的实验结果 ,以及在“闪光二号”加速器上已经获得的流强约 5 0kA的脉冲质子束。