共查询到20条相似文献,搜索用时 140 毫秒
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在工业辐照电子直线加速器中,电流发生器是电子束扫描设备中的重要部分,可控式电流反馈-电流镜产生扫描电流是一种新方法,其电流波形可被扫描均匀度指标修正,不仅可以得到良好的电子束扫描均匀度,而且还可以提高均匀扫描的速度。 相似文献
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通过改变磁场位形,利用粒子模拟方法,研究了相对论速调管放大器(RKA)中电子束收集位置对器件效率和工作稳定性的影响。合适的电子束收集位置对增加输出腔区束波作用强度、减小输出腔区强流电子束的空间电荷势能以及减少RKA中反射电子数量非常有利。对一个工作频率2.85 GHz的RKA的电子束收集方式进行了改进,在电子束参数为510 keV和8.1 kA,注入微波功率500 kW和导引磁场1.5 T时,模拟得到了1.4 GW的微波输出,效率33.7%,增益33.8 dB,改进电子束收集方式之前的模拟结果为输出功率1.1 GW,效率为26.3%。利用Surperfish设计了改进收集方式后所需的磁场位形,并导入粒子模拟程序进行了模拟,实现了对电子束收集位置的有效控制,输出效率为32%。 相似文献
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Penning阱存储离子的高分辨分析 总被引:1,自引:1,他引:0
根据Penning阱中存储和探测离子的原理,研究改善离子谱分辨率的有效措施,发现离子谱的分辨率与LC振荡回路的Q值、阱中离子的密度及LC回路的谐振频率等因素有关.实验中,谐振频率为480千赫兹,Q在120左右,电子束流在40微安左右,真空度合适时,得到了较高分辨率的离子谱.最后对离子谱进行了辨认,离子分别是H+3,H+5,H+6,H+7. 相似文献
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北京FEL电子束时间分辨能谱仪设计 总被引:1,自引:0,他引:1
从Wiggler出来的电子束,经过180°偏转后进人能谱和时间谱诊断系统。180°偏转段设计成既可等时又可消色散传输,等时传输是为满足对电子束微脉冲时间谱诊断,消色散是为满足电子束宏脉冲时间分辨能谱诊断。宏脉冲时间分辨能谱诊断系统由四台匹配透镜、双缝仪、扫描偏转线圈、90°对称双聚焦分析磁铁、位于焦平面的荧光靶、带有象增强器的视频摄象系统和在线计算机图象处理系统组成,其能量分辨好于1000,时间分辨好于60ns。 相似文献
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有效利用电子束在波荡器中运动时产生的谐波辐射,是获得更短波长辐射最直接的方法之一。提高波荡器磁场的谐波分量可以提高电子束的谐波辐射光场强度。分析了一种改进Halbach型波荡器结构,计算了其磁场的构成,分析表明这种结构可以使磁场的三次谐波分量提高至基波分量的25%左右。以合肥光源的电子束参数为例,计算了波荡器磁场谐波分量增强后对电子束自发辐射谱的影响。计算结果表明,波荡器磁场谐波分量增强至25%时,可以使电子束自发辐射的三次谐波辐射增强至基波辐射光子通量的67%左右。 相似文献
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典型的光谱角色散技术中,由于光束带宽受限于高效三倍频,因而无法通过增大带宽来进一步改善焦斑均匀性.结合对四色打靶方案和多级相位调制技术的综合分析,提出了多频、多色光谱角色散束匀滑新方案.该方案能在保持高效三倍频基础上,获得带宽有所加宽,光谱包络近似连续的光源,且在远场匀滑上具有更为独特的优势.结果表明,采用束匀滑新方案后,虽然焦斑会有所增大,但其均匀性却得到明显改善;与典型的束匀滑方案相比,该方案能更为有效地抑制热斑,且达到最佳匀滑效果所需的时间有所减短.此外,通过对阵列光栅中子光栅刻线方向的自由组合可以实现多维光谱角色散的效果. 相似文献
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在Cu基底上, 采用催化热解生长法制备了石墨化程度较高的碳纳米管阴极. 当电子束能量达到1 MeV、梯度约为60 kV/ns时, 发射束流强度达到15 kA, 相应密度约为1 kA/cm2, 束压、束流响应快, 波形间几无延时. 以50 Hz重复频率、约15 GW束功率强流发射时, 波形稳定, 随着频率增高, 稳定性降低. 发射炮次达1000后, 表面形貌保持完整、界面无脱附; 束压与束流基本满足空间电荷限制定律, 发射机理属闪络型等离子体发射, 等离子体速度约为3.9 cm/μs. 相似文献
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The effect of electron beam on the cathodoluminescence (CL) from MgO single crystals has been studied in the scanning electron microscope. It has been found that CL intensity and spectrum vary with irradiation time. The behaviour is discussed in terms of impurities and vacancy defects. 相似文献
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基于焦斑光强的空间频谱分析方法,建立了光谱色散匀滑技术(SSD)对焦斑匀滑的影响模型,提出了控制焦斑空间频率调制的响应函数.揭示了SSD参量对空间频率响应函数的影响规律.理论推导和数值模拟结果都表明:SSD对焦斑光强的频率响应具有周期调制性质,调制特性和色散角、光谱形状等相关.一般地,光谱形状控制空间响应函数形状,色散角决定所能匀滑的最低频率,色循环数可改变响应函数特点,调整对空间低频和高频的匀滑效果.空间频率响应函数的特点为多维SSD应用提出了应用准则.
关键词:
光谱色散匀滑
空间频谱
焦斑
响应函数 相似文献
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为了提高DG型电子加速器束流扫描均匀度、解决束流中心偏移、提升束流引出效率,开发了一种既可实现X,Y两相互垂直方向均匀扫描又可以实现束流中心自动对中调节的扫描系统。介绍了扫描磁铁及其电源参数的选取依据,阐述了将扫描磁铁和束流校正线圈进行整体式设计的扫描系统扫描电流成形方式及自动对中电路信号调制过程,包括为提高加速器运行安全性而设计的连锁保护信号。产业化现场使用事实已证明,该系统设计完全达到了设计要求,具有优良的扫描均匀度和长时间工作稳定可靠性。 相似文献
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A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned
at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance
because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current
profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine
the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool
to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving
technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate
the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile
in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile,
showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping
between the successive pulses of a scan to achieve ±5% dose uniformity along the scanning direction. A mathematical model,
which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is
discussed and the results are compared with the experimentally measured values, which show that the agreement is better than
15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in
the range of 1–13 kGy/pass. 相似文献
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在激光驱动惯性约束聚变研究中,束靶高效耦合依赖于采用合适的束匀滑措施.目前,结合光谱色散平滑(smoothing by spectral dispersion,简称SSD)、相位板和光束叠加的技术是固体激光驱动器采用的主流束匀滑技术.瞄准间接驱动,实验研究了一套基于线性调频脉冲的SSD技术.在采用该技术后,远场色散方向上的高频调制得到了匀滑,色散后的近场也得到了匀滑.测量得到的光谱结构与理论模拟接近.该方法不需要相位调制器,而这类器件在传统SSD技术中是一个关键器件. 相似文献
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Excitation of microwave by an annular electron beam in a plasma-filled dielectric lined waveguide 总被引:1,自引:0,他引:1
Jianqiang Wu Caidong Xiong Shenggang Liu 《International Journal of Infrared and Millimeter Waves》1995,16(9):1573-1581
An axial relativistic electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. This phenomenon of Cherenkov emission is the basis of all traveling wave tubes. In this paper an excitation of Cherenkov radiation by a thin annular relativistic electron beam in a plasma-filled dielectric-lined waveguide is analysed by use of the self-consistent linear theory. The effect of the thin annular electron beam on the beam-wave interaction is completely described by a jump condition. The dispersion equation and the simultaneous condition of the beam-wave interaction are derived. Finally, the growth rate of the wave is obtained, and the effect of the background plasma density and the electron beam radius on the growth rate of the wave are presented.This work is supported by National Natural Science Foundation of China. 相似文献
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《声学学报:英文版》2015,(3)
The low frequency line components of the radiated noise from an underwater target usually have both high spectrum level and sustained stability.This feature could be used to increase the detection performance of conventional broadband energy integration method.The required spectrum level is theoretically discussed when the detection performance of the known line detection is better than that of broadband energy integration method.Under the condition of the target can be detected in line spectrum band,the relationship between the line spectrum level and signal to noise ratio(SNR)is also discussed.This paper proposes a line spectrum target detection method that a matrix using DC jump to fluctuations ratios of sub-band spatial spectrum and beam space output is constructed.This matrix acts as a filter that the line spectrum target with certain frequency and azimuth is passed at most.By fusing with the other sub band results,the conventional detection performance can be improved.At the same time,the applicable condition and detection performance are analyzed in the paper.The simulation and the sea trial data processing results show that the algorithm can effectively extract weak goal line spectrum target under the condition of multi-interference.The algorithm doesn't need multi-frame statistics and the detection performance is closer to the optimal line spectrum method. 相似文献