High Density Plasma Heating by EC-Waves Injected from the High-Field Side for Mode Conversion to Electron Bernstein Waves in LHD

To realize an excitation of electron Bernstein waves (EBW) via mode conversion from X-mode waves injected from the high magnetic field side (HFS), new inner-vessel mirrors were installed close to a helical coil in the large helical device (LHD). 77 GHz electron cyclotron (EC) wave beams injected from an existing EC-wave injection system toward the new mirror are reflected on the mirror so that the beams are injected to plasmas from HFS. Evident increases in the electron temperature at the plasma core region and the plasma stored energy were observed by the HFS beam injection to the plasmas with the line-average electron density of 7.5×10 19 m 3 , which is slightly higher than the plasma cut-off density of 77 GHz EC-waves, 7.35×10 19 m 3 . The heating efficiency evaluated from the changes in the time derivative of the plasma stored energy reached ～70%. Although so far it is not clear which is the main cause of the heating effect, the mode-converted EBW or the X-mode wave itself injected from the HFS, an effective heating of high-density plasma over the plasma cut-off of EC-wave was successfully demonstrated.     

Measurement of the Electron Bernstein Wave Emission with One of the Power Transmission Lines for ECH in LHD

Possibility of the measurement of radiated waves derived from the thermally emitted electron Bernstein wave （EBW） is numerically investigated based on the assum...     

电子束焊机用的一种阴极加热电源

提出了一种新型的电子束焊机用阴极加热电源。本电源采用推挽逆变电路来实现功率转换 ,效率高、体积小。控制电路采用专用脉宽调制集成控制芯片 ,电路结构简单 ,便于调试和维修。电源还设置了软起动及过流保护电路 ,以防逆变功率开关管的损坏     

Signal emitted from plasma during electron-beam welding with deflection oscillations of the beam

The oscillations of a signal, collected by a ring electrode with +50 V potential, situated in the plasma over the welding zone during electron beam welding (EBW) with local beam deflection oscillations were studied. Samples of chrome-molybdenum steel were processed. The frequencies of the beam oscillations varied between 150 and 1400 Hz and their trajectories were the simplest: along and across the joint. The position of the beam focus was changed. Fluctuations of the emitted plasma current by coherent accumulation of the signal amplitudes were analysed and the probability for instability excitations in the keyhole was estimated. This method allows the study of the random instability processes at the interaction of the beam with the keyhole wall and bottom. A time shift between the maxima of the function derived from the coherent accumulation and the extremes of the deflection coil current was found. This shift depends on the beam focus position. In addition, at longitudinal beam oscillations, and at variations of the focus position a difference of the extreme values of the studied signal was observed. At the lowest values of the current of the focusing electromagnetic lens, the differences between the maxima of the probabilities for excitation of the plasma signal oscillations in the moments at beam bombardment on the front and trailing walls of the keyhole in the molten pool were about 30%, while the beam over-focusing decreased these differences. For beams situated at the central part of the keyhole, the collected signal was minimal. From the observations of spikes in the weld root, at EBW with deflection oscillations, it was concluded that self-focusing of the beam in the bottom part of the keyhole in the cases of the most focusing positions was occurring.     

Reduction of residual stress and deformation in electron beam welding by using multiple beam technique

The electron beam could be controlled by magnetic field for fast deflection, in which way multi-beam could be produced by deflection technique. The multi-beams run simultaneously for material processing with different heat input and positions. Therefore, it is possible to adjust the thermal effects and optimize the process. In this paper, the generation of multi-beams in electron beam welding (EBW) was investigated, and the processes of EBW with multi-beams were also investigated by both the numerical simulation methods, i.e., finite element analysis (FEA), and the experiments. The result shows that the residual stress of EBW could be minimized by using the multiple beam technique, and at the same time the welding deformation could also be reduced with the optimized parameters.     

电子束焊接在我国汽车零部件的应用与发展

介绍了电子束焊接汽车齿轮、液力变矩器涡轮总成、铝合金汽车驾驶舱横梁、涡轮增压器、行星轮架等部件在中国的应用概况，与发达国家在设备技术、焊接品种上的差距及其发展前景。     

电子束焊机中线性光电隔离装置的设计

电子束焊机线性光电隔离装置的开发，实现了高压电源与其控制系统的电气隔离，进一步提高了控制系统运行可靠性。     

Shape Character of Fusion-solidification Zone of EBW Joints for Titanium Alloy

Shape character of fusion-solidification zone of electron beam welding (EBW) joints was studied for TC4 alloy.Four typical shapes of the fusion-solidification zone were gained by appropriate welding processes.The shapes and dimensions of the fusion-solidification zone of TC4 titanium joints were apparently influenced by processing parameters,focusing state and power density distribution.Based on the analyses of processing parameters,focusing state and power density distribution,the integrated parameters of n1 and n2 were put forward,which represented the distribution and intensity of electron beam energy.And a series of the formulations are developed to predict the shape of fusion-solidification zone by the processing parameters.     

电子束焊焊缝超声C扫描检测技术研究

采用超声C扫描技术检测结构件的电子束焊焊缝。设计制作电子束焊焊缝模拟对比试样,利用模拟对比试样研究超声C扫描检测工艺。结果表明,超声C扫描技术可实现对结构件的电子束焊焊缝缺陷的定性、定位、定量检测。     

高频窄脉冲探头在从动盘超声检测中的应用

在汽车离合器从动盘电子束焊缝自动超声检测中,从动盘厚度薄、焊缝窄、缺陷微小,检测时易出现上下界面反射波混叠,界面回波与缺陷回波难以识别等现象。为提高超声检测系统的分辨率、灵敏度和信噪比,讨论了探头参数对检测结果影响,确定探头参数,并研制出了专用于从动盘超声检测的高频窄脉冲探头。参照欧洲标准对专用探头进行频率特性测试,测试结果表明:专用探头的频率特性明显优于普通探头,更有利于提高检测系统的灵敏度、分辨率和信噪比。在实际生产中将专用探头应用于从动盘自动超声检测中,可有效检测出当量尺寸约为0.4 mm的微小缺陷,并满足检测要求。