Effect of ion stress on properties of magnetized plasma sheath

In the plasma sheath,there is a significant gradient in ion velocity,resulting in strong stress on ions treated as a fluid.This aspect has often been neglected in previous sheath studies.This study is based on the Braginskii plasma transport theory and establishes a 1D3V sheath fluid model that takes into account the ion stress effect.Under the assumption that ions undergo both electric and diamagnetic drift in the presheath region,self-consistent boundary conditions,including the ion Bohm velocity,are derived based on the property of the Sagdeev pseudopotential.Furthermore,assuming that the electron velocity at the wall follows a truncated Maxwell distribution,the wall floating potential is calculated,leading to a more accurate sheath thickness estimation.The results show that ion stress significantly reduces the sheath thickness,enhances ion Bohm velocity,wall floating potential,and ion flux at the wall.It hinders the acceleration of ions within the sheath,leading to notable alterations in the particle density profiles within the sheath.Further research indicates that in ion stress,bulk viscous stress has the greatest impact on sheath properties.     

Etching and structure changes in PMMA coating under argon plasma immersion ion implantation

A thin (120 nm) polymethylmethacrylate coating was treated by plasma immersion ion implantation with Ar using pulsed bias at 20 kV. Ellipsometry and FTIR spectroscopy and gel-fraction formation were used to detect the structure transformations as a function of ion fluence. The kinetics of etching, variations in refractive index and extinction coefficient in 400-1000 nm of wavelength, concentration changes in carbonyl, ether, methyl and methylene groups all as a function of ion fluence were analyzed. A critical ion fluence of 10¹⁵ ions/cm² was observed to be a border between competing depolymerization and carbonization processes. Chemical reactions responsible for reorganization of the PMMA chemical structure under ion beam treatment are proposed.     

Temperature elevated N ion implantation of Ti6A14V alloys using the plasma source

1 INTRODUCTIONTi6Al4V alloys widely aPplied in aircraft comPorLents, cheAncal processing facilities,to medical jInplants, and so on because of its remaxkable mechaIilcal and chendcal prop-erties such as high strength-to-weight ratio and corrosj.on resistance[1]. However, the wearbehavior of titboum alloys in a tribological environInent is less satisfactoryl2l3]. Thereare reports on the effects of nitrogen ion imPlantation on hazdness, weax resistance, com-position and structure of Ti6…     

Influence of the residual oxygen in the plasma immersion ion implantation (PI3) processing of materials

In this work, we investigated the effects of the contaminants present in the vacuum chamber of the PI3 system, in particular, the residual oxygen, which results in the formation of the oxide compounds on the surface and hence is responsible for the high implantation energies required to achieve reasonably thick treated layers. We used a mass spectrometer (RGA) with a quadruple filter to verify the composition of the residual vacuum and pressure of the elements present in the chamber. Initially we found a high proportion of residual oxygen in a vacuum with a pressure of 1 × 10⁻³ Pa. Minimizing the residual oxygen percentage in about 80%, by efficient cleaning of the chamber walls and by improving the gas feeding process, we mitigated the formation of oxides during the PI3 process. Therefore we achieved a highly efficient PI3 processing obtaining implanted layers reaching about 50 nm, even in cases such as an aluminum alloy, where is very difficult to nitrogen implant at low energies. We performed nitrogen PI3 treatment of SS304 and Al7075 using pulses of only 3 kV and 15 × 10⁻⁶ s at 1 kHz with an operating pressure of 1 Pa.     

Formation of amorphous carbon on the surface of poly(ethylene terephthalate) by helium plasma based ion implantation

The surface modification of poly(ethylene terephthalate) (PET) by helium plasma based ion implantation (He PBII) was studied. The effect of the main process parameters (acceleration voltage, fluence and fluence rate) on the alterations of the surface chemical composition and structure were investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.According to SRIM calculations, at ion energies above 2 keV the stopping power of PET for He⁺ ions is dominated by the electronic component and the contribution of the nuclear component is relatively small. Degradation of the ester group and carbonisation were observed by XPS due to elimination of O-rich fragments. The total C-content of the modified layer increased with the increase of fluence rate and acceleration voltage of particles, enabling the purposeful alteration of the surface composition. A strong broadening was detected in the Raman spectrum between 1000 and 1700 cm⁻¹, testifying to the intense formation of amorphous carbon. The area ratio of the D (∼1410 cm⁻¹) to G (∼1570 cm⁻¹) band increased with the increase of particle fluence and the increase of acceleration voltage, offering the possibility of tailoring the chemical structure of the amorphous carbon layer created by the He PBII treatment.     

N+离子注入对锆-4合金耐腐蚀性能的影响

为了研究N+离子注入对锆-4合金耐腐蚀性能的影响,本文使用直线加速器产生的N+离子注入锆-4合金样品,通过对离子注入后样品电化学曲线的测量,分析不同剂量下N+离子注入对锆-4合金钝化电流密度的影响,同时使用透射电子显微镜分析注入层的微观结构.结果表明,随着注入剂量的提高(0-1×1016cm-2),样品钝化电流密度下降,耐腐蚀性能提高,其原因主要归结于样品表层由多晶结构到非晶结构的转变过程.     

离子注入与离子束混合两用机

早在1979年,为了解决应用于高温高真空环境下的轴承的自润滑问题,我们就着手采用     

离子注入对电器触头性能的影响

对两种电器触头注入1×10~(17)/cm~2的氮离子,然后做低压电器通断试验,测量了触头的重量损失、温升、接触电阻、触头材料转移等参数,发现离子注入方法处理对电器触头性能有不同程度的改善。     

镧离子注入对纯锆耐蚀性的影响

为了研究镧离子注入对纯锆耐蚀性的影响,样品表面分别注入了1×10~(16)-1×10~(17)cm-2的镧离子,使用MEVVA源作为注入源,注入能量为40 kv。X光电子谱(XPS)分析了注入样品表面镧的价态,三电极动电位扫描测定了注入样品在0.5 mol/L H2SO4溶液中的极化曲线,通过与空白样(未注入样品)比较可知,镧离子注入后,纯锆样品的耐蚀性大大提高。最后,讨论了耐蚀性提高的机理。     

脉冲注入中靶温对金属间化合物生成的影响

研究了在钢和Ａｌ中脉冲注入Ｔｉ和Ｍｏ的条件下金属间化合物形成的规律及生长机理，给出了金属间化合物生长与靶温的关系，得出的实验结果与计算相符合。与电镜中退火原位观察结果比较发现，注入过程中金属间化合物生长温度（４００℃）比退火中金属间化合物生长温度（６００℃）低得多，说明注入过程中空位流和间隙原子流能促进金属间化合物的生长。通过脉冲注入已得到十余种金属化合物和金属间化合物，这些化合物的出现提高了注入     

氮离子注入油菜M1代的生物学效应

研究了氮离子(N+)注入油菜干种子引发的当代生物学效应.结果表明N+在3.2×1016-4.6×1016/cm2注量范围内处理不影响油菜种子发芽;以3.9×1016/cm2注量处理可提高种子出苗率和成苗率;适当注量处理可促进苗期株高、叶片数和单株鲜重的增加,对成株期叶片数、茎粗、最大叶片长和宽等生物性状以及一次有效分枝数、全株总角果数和单株产量等经济性状均具有明显的生长刺激效应.同时,离子束处理区表现出广泛的变异,变异株率达到3.2%.     

Metal ion implantation in inert polymers for strain gauge applications

Metal ion implantation in inert polymers may produce ultra-thin conducting films below the polymer surface. These subsurface films are promising structures for strain gauge applications. To this purpose, polycarbonate substrates were irradiated at room temperature with low-energy metal ions (Cu⁺ and Ni⁺) and with fluences in the range between 1 × 10¹⁶ and 1 × 10¹⁷ ions/cm², in order to promote the precipitation of dispersed metal nanoparticles or the formation of a continuous thin film. The nanoparticle morphology and the microstructural properties of polymer nanocomposites were investigated by glancing-incidence X-ray diffraction and transmission electron microscopy (TEM) measurements. At lower fluences (<5 × 10¹⁶ ions/cm²) a spontaneous precipitation of spherical-shaped metal nanoparticles occurred below the polymer top-surface (∼50 nm), whereas at higher fluences the aggregation of metal nanoparticles produced the formation of a continuous polycrystalline nanofilm. Furthermore, a characteristic surface plasmon resonance peak was observed for nanocomposites produced at lower ion fluences, due to the presence of Cu nanoparticles. A reduced electrical resistance of the near-surface metal-polymer nanocomposite was measured. The variation of electrical conductivity as a function of the applied surface load was measured: we found a linear relationship and a very small hysteresis.     

离子注入提高高速钢W18Cr4V的耐磨性

1979年英国的N.E.W.Hartley采用注入CO~+的方式注碳,经CO~+注入的工具插件 (4Ni1Cr)和拉丝模(WC—6％CO),获得了磨损降低、寿命延长的好效果。1976年英国的I·H·Willson和1978年苏联的I.M.Belii曾分别报道用N~+注入Ti膜成功地合成了TiN,并对其电性能进行了系统研究。1981年中国台湾的P.A.Chen和T.T.Yang也用N~+轰击沉积在Si片上的1200A厚的Ti膜,成功地合成了化合物TiN,并用RBS和X-ray衍射对合成的化合物进行了鉴定。本实验采用CO~+注入高速钢,N~+注入高速钢表面镀Ti样品,与常规的N~+注入及空白样品进行对比,对注入后表面硬度和耐磨性的变化、注入层的成份、组织结构等进行了研究。实验结果表明,这两种注入工艺获得了比N~+注入更佳的效果。     

Effect of Fe ion implantation on tribological properties and Raman spectra characteristics of diamond-like carbon film

1 Introduction It is well known that DLC (diamond-like carbon)prepared by physical vapor deposition, plasma en-hanced chemical vapor deposition (PECVD) and otherplasma processing is an amorphous carbon materialcontaining sp2 and sp3 bonded carbon atoms. DLCfilm possesses some interesting properties, such ashigh hardness and Young's modulus, chemical inert-ness and low friction coefficient. The property andstructure of DLC film can be modified by addingsome metals. Ion implantation…     

低能氮离子注入对大豆幼苗脂质过氧化的影响

用N+注入丰豆101的种子,采收子叶伸展后24h和96h的幼苗做为试验材料,研究N+注入对其幼苗过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性以及氧化产物丙二醛(MDA)的含量、电解质外渗率的影响。结果表明,在25keV能量下,当N+注量在6.5×1016-7.8×1016N+/cm2时,幼苗的SOD和CAT活性最高。 而POD活性在小于5.2×1016N+/cm2低剂量下, 活性较恒定, 在大于5.2×1016N+/cm2中高剂量下,活性逐渐增大。此外,N+注入还可降低幼苗子叶中的MDA积累量和电解质外渗率,而且在6.5×1016N+/cm2剂量下,幼苗中的MDA含量和电解质外渗率最低。揭示了一定剂量N+注入大豆种子可削弱幼苗脂质过氧化作用以及提高其抗寒性的关系。     

高剂量注入中离子溅射的影响

在离子注入材料改性的研究过程中(金属、绝缘材料和光学材料等),在许多场合下,要求注入的元素(如Fe中注入N、Y、Ph和Sn等)在靶子中占百分之几的含量,这就要求注入剂量高达10~(17)/cm~2到10~(12)/cm~2。由于离子注入的溅射效应在低能和大剂量注入中是相当明显的,因此,对这些元素高剂量注入后的杂质分布、溅射系数、溅射厚度和靶子中杂质的收集量做一分析是十分重要的。     

聚苯胺的离子注入掺杂研究

研究了聚苯胺的离子注入掺杂对导电性的影响。用红外和紫外谱法探讨了聚苯胺的氧化态，本征态和还原态经离子注入后，其结构可能发生的变化。结果表明，聚苯胺的三种态的离子注入均为还原过程。讨论了离子注入掺杂的导电机制。     

氮离子束注入诱变选育胞外多糖高产菌株

采用氮离子束注入胞外多糖产生菌进行诱变处理来获得胞外多糖高产菌株.氮离子注入过程采用的能量为10 keV,剂量为60×1014-140× 1014 cm-2.根据其存活率及突变率确定最佳的注入剂量.结果表明:菌株存活率曲线遵循氮离子注入生物效应的“马鞍型曲线”,当注入剂量为120x 1014 cm-2时,获得了最佳的诱变效果.通过筛选和连续5次传代,获得具有良好稳定性的突变株,其多糖产量达到3.29 g/L,较出发菌株提高了19.20%,且发酵周期缩短了6h.     

高能磷离子注入硅晶格的损伤初探

对高能磷离子注入硅、低剂量迭加注入硅，高能低能双注入硅中引起的晶格损伤、二次缺陷及退火效应进行了初步探讨。     

Comparison of different plasma chambers in microwave ion source for the intense neutron tube

The microwave absorption efficiency, which is relevant to magnet field and its distribution, is a major parameter of the microwave ion source (MWIS) for the intense neutron tube. Based on previous work, the relations between microwave absorption efficiency and plasma chamber structure and thickness of the microwave introduction window are studied. The microwave absorption efficiency reaches to 100% when plasma chamber is 100mm long and the window thickness is 30mm. The microwave absorption efficiency as a function of pressure is also presented.