两种方法测量反射速调管的电子渡越时间及其比较

用静态法和动态法分别测量了K-19型反射速调管的电子渡越时间,并对两种方法测量的结果进行了分析和比较.     

Optimal Control of Trapped Electron Instability by a Modulated Neutral Beam

Equivalent lumped parameter system representation for dissipative trapped electron instability involving many modes is obtained. Optimal control theory in the presence of noise is used to design a stabilizing feedback network, with a modulated neutral beam as a remote suppressor. The optimality criterion is the minimization of the total energy of control and instability fluctuations. It is shown that the control power does not depend on the level of instability fluctuations in the absence of feedback, but on the noise level in plasma.     

利用Cherenkov光测量光电倍增管渡越时间涨落

采用符合方法,测量级联γ放射源⁶⁰Co在光电倍增管(PMT)光阴极窗上激发产生的切伦科夫光,从而测定PMT渡越时间涨落. 用泊松加高斯卷积方法获得单(多)光电子峰位,处理不同光电子数的~PMT~渡越时间涨落.测试XP2020和透紫XP2020Q PMT结果显示, 测量的渡越时间与菲利浦公司给出的指标一致, 渡越时间涨落与光电子数满足平方根反比关系. 该方法对可分辨单(多)光电子峰的~PMT~是可行的.     

刻槽绝缘平行板对电子束的导向效应研究

采用不同材质的刻槽绝缘平行板,包括高纯度石英玻璃、聚四氟乙烯（Teflon）、酚醛树脂（电木）和聚甲醛板（赛钢板）,并在15 pA/mm2 ~14.3 nA/mm2范围内改变入射流强,利用1 500 eV电子束入射上述绝缘平行板,实验研究了上述平行板对电子束的导向行为。实验发现,上述电子束通过上述平行板时存在明显的导向现象,其导向行为与束流流强和绝缘材质无关。据此,可排除绝缘平行板内表面沉积电荷自组织充放电过程中,以绝缘材料的面电阻和体电阻对地泄放的线性形式放电过程。Adopting several grooved parallel plates made by different insulators, such as high-purity fused quartz, Teflon, Bakelite and POM (Polyformaldehyde), and further adjusting the electron beam current in a wide range (tens of pA~tens of nA), the discharging mechanism in the self-organizing charge and discharge processes of electron guiding was investigated and discussed by using 1 500 eV incident electron beam. The present results show that, the electron guiding behaviors are obviously existing when such electron beam is transmitted through the above grooved insulating parallel plates, which are independent on beam current and insulators. Our results suggest that, the possibilities of the accumulated charges on inner-surface of grooved parallel plates linearly discharging through surface and bulk resistances of plates into the ground should be excluded.     

聚四氟乙烯密封材料的电子束辐射效应研究

采用低能电子束辐射系统地研究了操作氚系统用密封材料（聚四氟乙烯）的辐射效应。利用扫描电镜和X光电子能谱仪分析了材料的表观形貌和表面元素的变化,用X射线粉末衍射仪和热分析仪分析了辐照前后材料的结晶度改变和热稳定性程度,并利用气相色谱仪和质谱仪测定了辐射降解气体的成分和生成量随吸收剂量的变化规律。采用电子自旋共振谱仪研究了材料在辐照过程中产生的中间体（自由基）,利用正电子湮没寿命谱仪分析了材料中的自由体积孔洞及浓度。结果表明,辐照前聚四氟氟乙烯样品的表面是规则的带状晶形结构,经1×10^5Gy辐照后样品的晶状结构遭到了明显的破坏,向非晶态转变显著。辐照后样品的熔点和热分解温度均呈下降趋势,表明样品的热稳定性降低。聚。四氟乙烯材料在氧气气氛中发生的辐射降解最为严重,其次是真空,而在氘气气氛中辐射降解最少。材料的辐射降解主要发生在主链上,即C—C键断裂,而侧基C—F键的断裂相对较少。第三寿命强度I3的变化规律与τ3相反,即随吸收剂量的增大,第三寿命的强度I3降低,表明自由体积孔洞的浓度降低。 The radiation effect of polytetrafluoroethylene used as a kind of sealing material in the tritium system was studied by using electron beam. The superficial configuration and state were analyzed by SEM and XPS respectively, and the crystal degree and thermal stability were determined by XRD and DSC. At the same time the composition of gas products after radiation ,was measured by GC/MS, and the yield of CO2 with the dose increasing was analyzed. The free radicals produced in the process of radiation were studied by ESR, and the content of free volume of PTFE is analyzed by positron annihilation lifetime spectroscopy. The result is that the crystal structure of the sample irradiated at the dose of 1 × 10^5 Gy is of an obvious damage while the structure of the unirradiated sample is crystal band. The transformation of the sample which has high crystal degree amorphous one. The melting point and thermal ecomposition temperature trend sample＇s thermal stability drops. The radiation decomposition of the sample is is remarkable from crystal state to to decline, which indiccates that the mainly the rupture of C--C bond, and less is the rupture of C--F bond. The Intensity I3 of the third lifetime fails with increasing the absorbed dose, which demonstrates the reduction of free volume cave content. Compared with I3, the rule of τ3 is reverse.     

入射光调制对Ce∶KNSBN晶体两波耦合的影响

研究了入射光调制条件下Ce∶KNSBN晶体两波耦合动态过程.结果表明,入射光调制抑制了光扇噪音对Ce∶KNSBN晶体两波耦合动态过程的影响,提高了透射信号光强度.同时研究了入射光光强比Ip/Is及入射光总光强Io对最佳调制频率及增益改善Gm/Gf的影响.结果显示,同一Io下,Ip/Is为100时,Gm/Gf到达峰值1.52,对应的最佳调制频率为150 Hz;同一Ip/Is下,Io为57 mW/cm2时,Gm/Gf最大为1.53,对应的最佳调制频率为175 Hz.     

位相调制的实时联合变换相关器

提出一种位相调制的实时联合变换相关器。它采用液晶显示屏作为输入器件，用液晶光阀记录和显示联合功率谱。利用液晶显示屏上的光栅状结构的衍射级，提高光能的利用率，并充分利用液晶光阀的有效使用面积。采用成像透镜放大各衍射级的联合频谱，适应液晶光阀较低的分辨率要求。在相关器的光路中插入两块倾斜的平行平面玻璃板，以改变各衍射级的参考图像和目标图像之间的位相差。这种方法可产生比传统的实时联合变换相关器更好的输出相关性能。实验结果证实了该系统设计及性能分析的正确性     

脉冲光电子枪中光电子束性能研究

利用新设计的脉冲光电子枪,研究了光电子束的能量分布,光数密度与激光强度的关系和光电子在电离区内的滞留时间。大部分电子的能量为光发射电子的剩余能量,但量由于电子的空间电荷效应,电子能量分布具有加宽现象。每个激光脉冲发射到电离区内的光电子数密度在１０＾９／ｃｍ＾３以上。     

Electron transit time of PIN photodiodes fabricated in two-valley semiconductors

Electron transit time was calculated for a PIN photodiode with the absorption layer realized in two-valley semiconductor (GaAs, InGaAs...). Non-stationary effects and changes of the electric field along the layer result in a dependence of the electron transit time on both the applied voltage and the thickness of the layer. This dependence shows marked maximum and minimum, which could be important when modelling the response times of PIN photodiodes fabricated in these materials.     

CSR实验环电子冷却装置的纵向电子束温度

电子冷却装置中, 电子束纵向温度是计算冷却力的主要参量之一. 当电子与被冷却离子的相对速度很小时, 纵向冷却力与离子速度呈线性关系, 并且线性区域的宽度与电子束纵向温度有关. 通过分析影响电子束纵向温度的主要因素, 得到了兰州重离子冷却储存环实验环(CSRe)电子冷却装置中电子束纵向温度的大小.     

Whistler Wave Emission from a Modulated Electron Beam in a Collisional Magnetoplasma in the Presence of a Density Duct

We study the radiation from a modulated electron beam injected along the axis of a cylindrical density duct in a magnetoplasma. An expression for the average power lost by the beam at the modulation frequency is obtained and analyzed. It is shown that in the case of Cerenkov resonance of the beam with a weakly damped whistler mode of an enhanced-density duct, a noticeable increase in this power is possible compared with the case where the beam is injected in a homogeneous background magnetoplasma. Based on the results of numerical calculations performed for conditions of the Earth's ionosphere, we give estimates of an increase in the power radiated from the beam in the whistler frequency range in the presence of a cylindrical duct with enhanced density. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 9, pp. 730–742, September 2005.     

光折变光栅在超短脉冲光照射下衍射的研究

利用Kogelnik单色光在体光栅中衍射效率公式推导出超短脉冲光读出稳态光折变体光栅时的衍射光频谱表达式,并在此基础上导出了脉冲光读出时的总衍射光强及总光强衍射效率.研究发现衍射光的频谱分布、总光强及衍射效率与光栅周期Λ、光栅厚度d和读出光脉冲宽度Δτ有密切的关系.通过调整这些参量,光折变光栅可以对入射的超短脉冲光实现不同程度的滤波作用.该结论可用于超短脉冲的整形研究.     

Study of Low Sidelobe Time Modulated Linear Antenna Arrays at Millimeter-Waves

In this paper, the time modulation technique for the design of low sidelobe antenna arrays is extended to millimeter-wave frequency band. Millimeter-wave rectangular waveguide is selected as the element radiators of linear antenna arrays, and the element radiation patterns are taken into account in the analysis and design of low sidelobe time modulated linear arrays. Two types of time modulation, namely, the time modulated variable aperture sizes (VAS) and unidirectional phase center motion (UPCM), are implemented in the design of low sidelobe millimeter waveguide linear arrays. It is observed that both the co-polarized and the cross-polarized components will experience the time modulation effect simultaneously. Many factors that affect the array performance are discussed.     

基于场致发射阴极阵列的太赫兹源的物理机理研究

本文对一种基于场致发射阴极阵列(FEA)的太赫兹辐射源的物理机理进行了理论分析和粒子模拟验证. 采用场匹配法分析了器件的高频场结构, 确定π模作为器件的最优工作模式; 利用线性理论分 析了器件的注波互作用过程, 揭示了高频场对FEA阴极发射电流的预调制作用以及电子在阴阳极间隙的渡越时间效应 是器件起振的物理原因; 分析得出了π模起振条件; 粒子模拟结果与理论分析具有较好的一致性.     

短脉冲高斯光束的时空形式

考虑到腔模光腰尺寸的频率依赖性，得到了一短脉冲高斯光束在自由空间传播的时域解析形式，发现其可由一复时间变量来描述，复时间变量的实部给出了脉冲的传输时间，其与波前曲率有关，虚部给出了空间量值，两者的交叉项称为时空耦合，并对傅里叶变换极限脉冲和啁啾脉冲的时空形式作了分析。     

HIRFL-CSR电子冷却束流位置测量系统

高效率的电子冷却过程, 要求电子束与离子束位置平行且重叠。 为了同时测量电子束与离子束的位置, 在HIRFL CSR电子冷却装置上研发了以容性圆筒形极板为感应电极的束流位置探测系统。 系统测量束流通过探针时产生的脉冲感应信号, 并进行傅里叶变换得到频谱信号, 分析4个不同电极上频谱信号强度获取束流的位置信息。 测量结果表明, 该束流位置探测系统测量准确, 为定量研究储存环离子累积和电子冷却过程与两种束流相对位置及角度的依赖关系提供了条件。 The efficient electron cooling requires that the ion beam and electron beam are parallel and overlapped. In order to measure the positions of ion beam and electron beam simultaneously, a beam position monitor system is developed for the HIRFL-CSR electron cooler device, which probe consists of four capacitive cylinder linear cut poles. One can get the both beam positions from the picking up signals of four poles by using Fourier transform(FFT) method. The measurement results show that the beam position monitor system is accurate. This system is suitable for investigating the relation between electron cooling processing and the angle of ion beam and electron beam.     

Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma IV. Excitation of Nonresonant Waves

A system of nonlinear equations derived in a previous paper which describes the evolution of nonresonant waves in beam-plasma systems is solved numerically. It is given a physical interpretation of essential features of the nonresonant beam-plasma instability. The significant influence of higher harmonics on the evolution of an electron beam in the plasma which is modulated on a nonresonant unstable frequency, is investigated. The interaction of unstable nonresonant and resonant waves in beam-plasma systems is examined. It is shown that the evolution of resonant waves can be essentially influenced by an initial modulation of the beam on an unstable non-resonant frequency. The role of an initial velocity modulation of the beam for the influence of the wave spectrum is demonstrated.     

The Energy Spectrum of the Electron Beam of a Betatron

The process of extraction of an electron beam through the glass wall of a sealed-off acceleration chamber has been investigated. It has been shown that the electron beam extracted from the MIB-6E small-sized betatron has a nonuniform cross-sectional distribution of the particle flux density. This nonuniformity is due to the imperfection of the beam extraction devices and to the flaws in design of the extraction window of the accelerator chamber. The electrons extracted through the glass wall of the window lose a major portion of their energy. At the outlet of the chamber of the small-sized betatron, the spectrum of the electrons is not line. The half-width of the spectral line of the electron beam is, at best, 6% for a window glass thickness of 0.5 mm and about 15% for a glass thickness of 4 mm. The results of this study may find practical implementation in developing extracted electron beam formation systems.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 51–55, January, 2005.     

聚酯材料在脉冲电子束辐照下的动力学效应与材料参数

对聚酯材料在电子束辐照下的动力学效应进行了研究。采用Monte Carlo方法,计算了脉冲电子束在聚酯材料中的能量沉积;采用流体动力学方法,对聚酯材料在电子束辐照下的热击波和喷射冲量进行了数值模拟;采用将喷射冲量和热击波压力的数值结果与实验测量结果进行逼近的方法,得到了聚酯材料的升华能约为1.1 kJ/g,Grüneisen系数的常态值约为0.2。     

合肥光源电子束流能量标定的前期研究

为了在合肥储存环上利用共振退极化的方法建立一套测量电子束能量的装置, 进行了物理计算,