共查询到19条相似文献,搜索用时 109 毫秒
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激光等离子体加速输出的电子束具有fs量级脉冲长度的优异品质。由于强激光场的存在,直接应用存在一定困难,更多应用场景需要把电子束传输到应用端。能散导致电子束在传输中产生能量啁啾,需要通过束流光学设计抑制脉冲长度的增长。通过对电子束在消色差束线中传输的研究,探索了消色差和非消色差传输中脉冲长度压缩的差异,以及消色差束线中偏转角度、偏转半径对不同能量电子束脉冲长度压缩的影响。针对消色差传输中仅有某个能量电子束得到最优压缩的局限,利用四极透镜磁场梯度的调节使电子束的传输适度偏离消色差,改变对能量啁啾的影响,实现在固定尺寸束线中不同能量电子束的压缩。 相似文献
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本文简要介绍了灵敏面直径分别为20,12mm,中心孔为4mm的环形探测器的制造工艺和基本性能。并给出了扫描电子显微镜和扫描电子束爆光机中,采用环形探测器检测背散射电子的实验数据、曲线及扫描图象。 相似文献
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北京慢正电子强束流性能研究 总被引:1,自引:1,他引:0
采用电子束流以及脉冲慢正电子束流对系统进行了调试,对束流系统的性能参数进行了测定和研究。实验结果表明,系统对于模拟电子的传输效率高于98%,电子束斑直径小于5mm。在目前加速器短脉冲的运行模式下,脉冲慢正电子束流的强度达到了105/s以上,IP成像板束流沉积形貌直径小于15mm,脉冲慢正电子束流微分能谱半高宽(FWHM)约为10eV;;在高于3×10?Pa的超高真空中,慢正电子在直流化管道内7存贮40ms后,束流强度减弱到原来的50%。系统各项性能运行参数达到了设计要求。 相似文献
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讨论了有外加磁场情况下,强流相对论电子束传输过程中的电荷中和理论,着重讨论了二次电子逃逸时间和外加磁场对空间电荷中和的影响。得知当电子束半径大于2.0 cm 时,在计算空间电荷中和时间时就得考虑二次电子逃逸时间的影响。在一定条件下,外加磁场对空间电荷中和有阻碍作用,对于长漂移室,存在空间电荷中和允许的磁感应强度上限。 相似文献
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推导了Modifled—Ψ法应力测试及其穿透深度的计算公式,并利用它测试了铍环形焊件热影响区和基体材料中的残余应力。对电子束焊接的铍环其焊缝附近外表面为拉应力,内表面为压应力。由于Modified—Ψ法透入深度太大,不能用来测定铍的表层残余应力,引入多波长法成功地测试出了铍环表层的应力及应力随层深的分布。同时针对电子束焊接过程的特点,编写了用于应力场计算的有限元分析程序。运用编写的程序分别对不同尺寸及焊接工艺的三个铍环电子束焊接样品进行了有限元分析,并将计算结果与实测值进行了比较。结果表明:有限元计算结果与实测值吻合得较好,为先期预测焊件中残余应力的大小和分布从而优化焊接工艺提供了参考依据。 相似文献
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推导了 Modified-ψ 法应力测试及其穿透深度的计算公式,并利用它测试了铍环形焊件热影响区和基体材料中的残余应力。对电子束焊接的铍环其焊缝附近外表面为拉应力,内表面为压应力。由于 Modified-ψ 法透入深度太大,不能用来测定铍的表层残余应力,引入多波长法成功地测试出了铍环表层的应力及应力随层深的分布。同时针对电子束焊接过程的特点,编写了用于应力场计算的有限元分析程序。运用编写的程序分别对不同尺寸及焊接工艺的三个铍环电子束焊接样品进行了有限元分析,并将计算结果与实测值进行了比较。结果表明:有限元计算结果与实测值吻合得较好,为先期预测焊件中残余应力的大小和分布从而优化焊接工艺提供了参考依据。 相似文献
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《中国原子能科学研究院年报(英文版)》2018,(0)
正电子束3D打印光路仅由1个螺线管和1个偏转磁铁构成,虽然其结构简单,但是要求束斑尺寸达到0.1mm左右,这对于10mA/60kV的强流低能电子束的难度很大,特别是光路还要求大角度偏转。对于无偏转光路,采用Trace3D对光路进行动力学计算的结果如图1所示,螺线管场强为103G。电子束传输过程中的电荷中和率为0.1%,即电流实际流强为10 mA,电荷中和后的流强为0.01mA,所得束斑半径为0.09mm。 相似文献
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叙述了一种用于局部真空电子束圆形焊缝的自动跟踪系统的设计和试验过程。在局部真空电子束焊接精密结构件的圆形法兰焊缝时,由于加工偏差、工装累计误差等原因,出现电子枪回转中心与焊缝圆心不同心现象。使用本控制系统,使转台在起始位置时,用小束流电子束对准工件扫描,利用电子束在焊缝上和在工件上产生的二次电子数量不同而检测出焊缝起始点位置。利用相同工作原理,再用小束流对整条圆焊缝进行扫描,并由计算机实时记录整个圆形焊缝上各点与扫描线圈电流过零时电子束束斑间的偏差值,完成一个示教过程;然后由计算机处理与分析所获取的数据并存贮;在焊接时利用处理后的偏差值在圆形焊缝相应位置不断修正电子枪的位置,从而达到电子束束斑与焊缝自动对中的目的。 相似文献
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B. L. Doyle G. Vizkelethy D. S. Walsh D. Swenson 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):19-25
A new system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratory in Albuquerque. This system combines two entirely new concepts in accelerator physics and nuclear microscopy. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff–Pelletron to velocities of 1.9 MeV/amu. The electronic stopping power for heavy ions is near a maximum at this velocity, and their range is 20 μm in Si. These ions therefore represent the most ionizing form of radiation in nature, and are nearly ideal for performing single event effects testing of integrated circuits. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor ( a few %), which makes problematic the focussing of such ions to the submicron spots required for REM. To circumvent this problem, we have invented ion electron emission microscopy (IEEM). One can perform REM with the IEEM system without focussing or scanning the ion beam. This is because the position on the sample where each ion strikes is determined by projecting ion-induced secondary electrons at high magnification onto a single electron position sensitive detector. This position signal is then correlated with each REM event. The IEEM system is now mounted along the beam line in an axial geometry so that the ions pass right through the electron detector (which is annular), and all of the electrostatic lenses used for projection. The beam then strikes the sample at normal incidence which results in maximum ion penetration and removes a parallax problem experienced in an earlier system. Details of both the RFQ-booster and the new axial IEEM system are given together with some of the initial results of performing REM on Sandia-manufactured radiation hardened integrated circuits. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(5):698-702
The electron beam in medium scale (1-2 GeV) synchrotron radiation ring is attractive to generate an intense and narrow energy spread of laser-Compton gamma-ray beam in an MeV-region. Since the storage ring is operated with fixed electron energy for synchrotron radiation (SR) users, methods for changing the gamma-ray energy should be investigated. Three methods, 1) using a tunable laser, 2) changing the collision angle between the laser and the electron beam, and 3) selecting the scattering angle of the laser-Compton gamma-ray by using a collimator and an absorber, are studied by analytical calculation and simulation which takes into account the electron beam size and effective length of laser-electron interaction. Since a tunable laser has no enough power in the infrared wavelength region, an intense gamma-ray beam can not be generated by using a tunable laser at present stage. The collimator-absorber method generates enough amounts of gamma-rays, but simulation shows a broad energy spread, -7%, of the gamma-ray. An acceptable gamma-ray beam can be obtained by changing the incident angle of the laser beam whose pulse width and timing are synchronized with the electron beam pulse. 相似文献
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DAIZhi-Min 《核技术(英文版)》2005,16(2):65-69
In this paper, a new mechanism of electromagnetic instability, the induced ion-channel instability, is studied. It is based on the transverse driven betatron oscillation of relativistic electron beam induced by an additional magnetic undulator with a period close to the betatron wavelength in an ion channel. As its amplitude is sensitive to the electron beam energy, the driven betatron oscillation may determine electron beam grouping in the ponderomotive potential by selecting the undulator strength and period, and it provides a new mechanism of electron bunching, resulting in electromagnetic instability. Under proper condition, a new free-electron laser based on this mechanism may be realized. 相似文献
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In recent years, people are looking for a new compact THz source with high emission power, one potential choice is to build small accelerator with Smith-Purcell radiation. The main difficulty is how to obtain high quality electron beam. In this paper, the beam dynamics design of a compact THz source is presented. The electron beam is produced by an electron gun and compressed by permanent magnets. The electron gun is similar to the Shanghai EBIT,but permanent magnets are used, instead of the superconducting magnets in Shanghai EBIT. With this design, we can reduce the size and cost of the whole device. Poisson/Pandira was employed to simulate and optimize the magnetic field. Egun was used to simulate the beam trajectories from the electron gun to the collector. Within 2 centimeters around the center of longitudinal magnetic field, the calculation showed that the beam satisfies to our design aim. 相似文献