共查询到20条相似文献,搜索用时 15 毫秒
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Ranajoy Bhattacharya Naveen Kr Sahu Arani Ali Khan Hasina Khatun A.K. Sinha 《Fusion Engineering and Design》2013,88(4):253-257
The paper presents the electrical and thermo-mechanical design of single stage beam recovery system for 120 GHz, 1 MW gyrotron. The electrical study shows that the cylindrical shape single stage beam recovery system enhances the efficiency by 66.26%. The maximum power deposited to collector in depressed collector operation is 0.48 MW for electronic efficiency, 30% and 1.44 MW for DC electron beam. The thermo-mechanical analysis has been performed to evaluate the water cooling system. The cooling system has capability of accommodating a peak wall loading, 0.9 kW/cm2 at flow rate of 1500 l/min for safe operating time, 60 ms. Further, a high voltage analysis is also carried out to appraise the electric field distribution in the collector. 相似文献
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Roger HUTTON 《核技术(英文版)》2003,14(4)
A brief introduction to the historical background and current status of electron beam ion traps (EBITs) is presented. The structure and principles of an EBIT for producing highly charged ions are described. Finally, EBITs as a potential tool in hot-plasma diagnostics and in studying frontier problems of highly charged ion physics are discussed. 相似文献
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研究基于简单解析表达式的电子背散射系数与入射电子能量、介质厚度和能损的关系及其对电子束辐射加工的影响,考虑到入射电子在多层介质之间反复的穿透和背散射,编制了ED410程序,计算了不同补底材料和不同入射电子能量下能量沉积的深度分布和剂量因子,利用补底要 背散射抬高接近补底界面处的剂量,较大地改善了辐射加工的均匀性。 相似文献
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E.D. Donets 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1985,9(4):522-525
The present-day situation and prospects for the development of electron beam ion sources are considered and associated investigations of the physics of highly ionised atoms at JINR Primary consideration is given to experiments based on measurements of X-ray spectra.Specific features of the experiment include statements of QED in strong fields using electron beam ion sources. 相似文献
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以甲苯作为挥发性有机化合物的代表物质,在800keV电子束的辐照下,模拟甲苯废气的气量在0.5—1.2m3/h范围内,研究了甲苯初始质量浓度为1600—4630mg/m3时吸收剂量、甲苯初始浓度和湿度对于甲苯分解效率的影响。实验结果表明,电子束辐照可有效去除甲苯,甲苯初始质量浓度为1600mg/m3,辐照10kGy和40kGy,甲苯去除率分别为46.5%和72.2%;增加湿度也可提高甲苯去除率。用气相色谱-质谱仪(GC-MS)和离子色谱仪(IC)定性研究了辐解产物。甲苯辐解产物比较复杂,主要含有苯甲醛、甲酸等物质。也探讨了电子束辐照处理甲苯气体的主要机理,讨论了O2和.OH对于电子束辐照分解甲苯中的重要作用。 相似文献
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The effects of repetitive pulsed heating and melt layer formation on type 304 stainless steel are reported. A line-source electron beam with pulse times of 0.5 or 1.5 ms and power densities up to 100 kW/cm2 has been used for 1–40 pulse cycles at 500°C substrate temperatures. Numerical calculations of the temperature profiles and their time evolution during melt layer formation are also carried out. Significant metallurgical changes are observed, both in the melt layers and in the adjacent heat-affected zone. Melt depths (10–20 μm) are consistent with calculations and the resolidified regions exhibit columnar or columnar-dendritic microstructure. Appreciable lateral motion within the molten layer results in very rough surfaces and localized cracking occurs. Extensive slip deformation is seen in the adjacent heat-affected zone, and low-cycle fatigue crack initiation is observed after only 20 pulses. Chemical changes in the stainless steel melt layer result from the preferential vaporization of Mn from the melt layer and correlate with the time in the liquid phase. We suggest that the preferential loss of high vapor pressure species such as Mn in the early phases of plasma device operation might provide a unique signature of the impurity introduction mechanism. Disruption melted compositions are distinctly different from the more-nearly stochiometric ratios of Mn/Cr/Ni expected for sputter erosion. 相似文献
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《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1986,17(2):137-140
The Auger beam surface charge build-up during deposition of thin layers of Cu upon MgO(100) and MgO(111) crystal surfaces was investigated. A three step model is proposed: 1) copper induced electron trapping, 2) formation of local conduction band in a thin metal film, and 3) formation of continuous isolated metal. 相似文献
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M. Mohapatra R.M. KadamR.K. Mishra D. DuttaP.K. Pujari C.P. KaushikR.J. Kshirsagar B.S. TomarS.V. Godbole 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(19):2057-2062
Spectroscopic investigations were carried out on electron beam irradiated sodium barium borosilicate glasses, which is the base glass for immobilization of nuclear high level radioactive waste, generated from the research reactors at Bhabha Atomic Research Centre, Trombay. This was done in order to access the defects generated in it under long term irradiation. Electron paramagnetic resonance was used to identify the defect centers generated in the borosilicate glass after irradiation. In addition, positron annihilation spectroscopy and infrared investigations were done on the samples to evaluate the radiation induced changes in the glass. It was found that, boron-oxygen and silicon based hole centers along with E′ centers are getting formed in the glass after irradiation due to the breaking of the SiO bonds at regular tetrahedron sites of SiOSi. The positron annihilation spectroscopy data gave an idea regarding the free volume size and fraction of the glasses before and after irradiation. It was seen that, after irradiation the free volume size in the glass increased with creation of additional sites. Microwave power variation and temperature variation studies suggested the formation of at least five different radicals in the irradiated glasses. The spin Hamiltonian parameter of all the radical species were determined by computer simulation. An electron paramagnetic resonance spin counting technique was employed to evaluate the defect concentration in the glasses after irradiation. 相似文献
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A. A. Bettiol I. Rajta E. J. Teo J. A. van Kan F. Watt 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):154-159
Proton beam micromachining (PBM) is a direct write lithographic technique that uses a focused beam of MeV protons to pattern a resist material. The most common resist material used in the PBM process is SU-8 which is usually spin coated onto various substrates. The method used to ensure that the correct dose is delivered to the sample during irradiation is Rutherford backscattering spectrometry (RBS). There are however limitations to using the RBS signal for normalizing the dose in highly sensitive resist materials such as SU-8. The limited number of backscatter events means that normalizing the dose for every pixel is not possible. The secondary electron yield for SU-8 is at least an order of magnitude higher than that for backscattered ions. With an appropriate detector these signals can be essentially used for ion detection and thus used to accurately monitor ion dose. In this paper we investigate the secondary electron yield from SU-8 polymer resist layers of varying thickness on silicon. It is shown that the signals produced during MeV ion irradiation can be directly related to the ion dose and used for dose normalization during PBM. 相似文献
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Review of quasi-optical gyrotron development 总被引:1,自引:0,他引:1
A. W. Fliflet T. A. Hargreaves R. P. Fischer W. M. Manheimer P. Sprangle 《Journal of Fusion Energy》1990,9(1):31-58
There is currently a need for megawatt average power sources of 100–600 GHz radiation for electron cyclotron heating of fusion plasmas. One of the leading candidates for such a source, the conventional wave guide cavity gyrotron,(1) has produced impressive output powers and efficiencies at frequencies up to about 300 GHz. However, this gyrotron configuration is limited at high frequencies by high ohmic heating and problems with transverse mode competition due to the highly overmoded configuration, and with beam collection, since the beam must be collected along a section of the output waveguide. The quasi-optical gyrotron (QOG), first proposed in 1980 by Sprangle, Vomvoridis, and Manheimer,(3) features an open resonator formed by a pair of spherical mirrors instead of a waveguide resonator and has the potential for overcoming each of these limitations. The resonator mirrors can be well removed from the beam-wave interaction region, allowing a large volume for the interaction and low ohmic heating densities at the mirrors. The beam direction is transverse to the resonator so that beam collection is separate from the output waveguide. This geometry is particularly well suited to the use of a depressed collector for electron beam energy recovery. The QOG operates in the lowest-order transverse (TEMool) Guassian mode of the resonator, higher-order transverse modes being effectively suppressed by higher diffraction losses. This paper reviews recent progress toward the development of high-power quasi-optical gyrotrons for ECRH of fusion plasmas. It includes an overview of gyrotron theory in terms of normalized variables as they apply to the quasi-optical gyrotron for operation both in the fundamental and the higher harmonics. Scaling equations for the output power and resonator mirror heating by the RF are given. The design tradeoffs between annular and sheet electron beams are discussed as is the issue of beam space-charge depression in the open resonator. Recent advances in the analysis and design of QOG configurations capable of efficient and stable single-mode operation are discussed, showing the possibility of achieving 50% transverse efficiency in highly overmoded resonators. The application of a depressed collector is discussed as a means of recovering the energy in the axial motion of the spent electron beam and, thus, raising the output efficiency to near the transverse electronic efficiency. The problem of high field magnet design is addressed, for both fundamental and higher harmonic operations, the latter being necessary at very high frequencies. The design equations and tradeoffs are applied to the design of 1-MW, CW quasi-optical gyrotrons operating at 120 GHz, in the first and second harmonic at 280 GHz and in the second harmonic at 560 GHz. The output coupling for these 1 MW designs is 5–7% showing the potential for even higher powers per tube if sheet-beam electron guns can be developed. The estimated electronic efficiency of the fundamental harmonic designs is 23%, which leads to an output efficiency of 47% with the use of a depressed collector with a modest collection efficiency. The peak ohmic heating density is 500 kW/cm2 in all the designs. This leads to resonator mirror separations ranging from 127 cm for 120-GHz design, to 232 cm for the 560-GHz, second harmonic design. Finally, a simple output system composed of'elliptical and parabolic mirrors is described that converts the output radiation from the resonator into a parallel, quasi-Gaussian beam. Experimental programs are reviewed as well, including the recent experiment at the Naval Research Laboratory that produced frequencies ranging from 95–130 GHz and powers up to 150 kW. Operation in a single mode was observed at powers up to 125 kW despite the resonator being highly overmoded. Comparison is made with the theoretically-predicted region of single-mode operation. Recent progress in the experimental characterization of QOG resontors is summarized. 相似文献
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Mary E. Sullivan Giuseppe R. Palmese 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):352-355
The development of nanotube-based polymer composites with improved mechanical properties and electrical conductivity requires the covalent dispersion of carbon nanotubes to utilize their stress transfer capabilities. Covalent dispersion of nanotubes therefore requires the functionalization of their surface to interact with solvents or monomers. In this work, we have developed a novel method of nanotube surface modification in which dry MWNT are irradiated with a high-energy electron beam (EB) in ambient air environment. Raman spectroscopy was performed to characterize the influence of EB irradiation on nanotubes, namely, variance of the disorder, or D band (∼1360 cm−1) with respect to the graphitic, or G, band (∼1580 cm−1). Raman spectra show increased deformation to the graphitic structure, as well as increased strain on the carbon-carbon bonds, weakening the nanotube. Transmission electron microscopy (TEM) confirms that nanotubes remain intact despite high EB dose. In addition, minimal surface deformation and length reduction occurred on irradiated MWNT. 相似文献
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Gregor Kowarik Michael Brunmayr Friedrich Aumayr 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(16):2634-2637
Tungsten has recently been introduced as a new wall material for fusion, because it exhibits favourably low sputtering yields and a very low tritium retention as compared to the commonly used graphite wall and divertor tiles. We measure total electron emission yields due to impact of slow singly and multiply charged ions (deuterium, helium and carbon) on sputter-cleaned polycrystalline tungsten surfaces by using a current method in combination with a retarding grid. Results are presented in the eV to keV impact energy region as typical for fusion edge plasma conditions and discussed in terms of potential and kinetic electron emission. 相似文献
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《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1988,30(1):90-93
Applicability of the 32S(p, p′ γ)32S reaction for sulphur analysis as a complementary method to PIXE has been investigated. The optimum energy region for the bombarding protons has been determined for both thick samples and for thin atmospheric aerosol samples. By optimizing the external beam method, sulphur concentrations at the 100 ppm level for thick organic samples and at the 100 ng/cm2 level for aerosol samples are detectable. 相似文献