基于CT算法的束团横向相空间测量

精确测量束团的发射度和横向相空间, 在高亮度电子束的产生和应用中具有重要意义. 传统测量方法在测量发射度时需要对束团在相空间内分布进行初始假设, 且只能给出相椭圆的twiss参数;基于CT(computerized tomography)算法的束团横向相空间测量方法无需先验假设, 能给出粒子在相空间内的真实分布, 测量结果更为精确. 介绍了基于CT算法的束团横向相空间测量的原理和初步实验结果, 并与四极透镜扫描法测量的结果进行了比较.     

CSNS RCS注入横向相空间涂抹的研究

中国散裂中子源(CSNS)加速器系统由80MeV的直线加速器和1.6GeV的快循环同步加速器(RCS)构成. CSNS第一阶段采用H^－剥离注入方法, 将粒子数累积至1.88×10¹³. 注入束流被涂抹在较大的横向相空间内, 以减小空间电荷效应. 粒子注入后, 为了降低由空间电荷效果引起的工作点漂移和工作点弥散, 束流分布的均匀性很重要. 引入了评估束流分布均匀性的三个参数. 为了抑制注入过程中束流发射度和束晕的增长, 通过采用三维的模拟程序ORBIT, 对不同的横向相空间涂抹方案进行了比较. 同时还介绍了工作点、注入峰值流强和斩波调制比等因素对注入过程的影响.     

On the Plasma Beam Instability of the Space Limited Electron Beam in a Magnetic Field

The present paper considers the plasma-beam instability of a space limited electron beam in a strong magnetic field (ω_H ? ω_o). The form of the beam was taken to be both cylindrical and plane. The threshold of the non-linear regime turned out to be weakly dependent on the beam form and independent of the magnetic field intensity. It is defined by the current and the directed velocity of the beam particles.     

BEPC中的电子云不稳定性研究

多束团正电子储存环中可能发生电子云不稳定性(ECI). 自1996年起, 在北京正负电子对撞机(BEPC)上开展了与这种束流不稳定性相关的系列研究. 文章扼要介绍在BEPC上进行的电子云不稳定性研究, 包括实验观测和模拟计算, 并讨论可能的抑制措施.     

φ36的媒质效应和热不稳定性

在有限温度下运用硬热圈近似求得φ36理论单圈自能,进而求得有限质量和衰变率. 发现在临界温度Tc以上存在热不稳定性,而有效温度和衰变率则分别正比于gT和gT. 最后将所得结果与热QCD比较.     

Velocities of Longitudinal and Transverse Elastic Vibrations in Superionic Silver Sulfide

JETP Letters - A system consisting of material particles and a field is studied. The latter is described by the nonlinear Klein—Gordon equation. A modified Klein—Gordon equation, which...     

非线性腔中横模的时空不稳定

通过数值模拟研究了非线性腔的横向效应，非线性表现在光场通过放大介质时所引起的相位变化与强度有关，模拟结果显示，随着非线性系数的变化，腔中的光场分布表现丰富的时空不稳定行为，其中包括横模跳变，时空周期行为以及光学涡旋的出现。     

Instability Entanglement in the Electron Cyclotron Maser

Investigation of absolute instability (AI) and convective instability (CI) of the electron cyclotron maser has independently led to the birth of gyrotron oscillators and amplifiers. Here, it is demonstrated that these instabilities can form a cooperative relationship owing to the nonlinear behavior of the stimulated electron beam. The CI can be induced in a zero-drive system with the assistance of AI, and the ohmic losses of all the excited waves inside the system are greatly reduced, which is called “instability entanglement” here. According to the theoretical and experimental study of a 167/330 GHz gyrotron, when instability entanglement occurs, the ohmic dissipation decreases to one-ninth of the AI-only condition, and the output power is enhanced by 20%. This discovery is promising for surpassing the ceiling of output power and frequency of gyrodevices placed by ohmic losses.     

An Algebra of Effects in the Formalism of Quantum Mechanics on Phase Space

Defining an addition of the effects in the formalism of quantum mechanics on phase space, we obtain a new effect algebra that is strictly contained in the effect algebra of all effects. A new property of the phase space formalism comes to light, namely that the new effect algebra does not contain any pair of noncommuting projections. In fact, in this formalism, there are no nontrivial projections at all. We illustrate this with the spin-1/2 algebra and the momentum/position algebra. Next, we equip this algebra of effects with the sequential product and get an interpretation of why certain properties fail to hold. PACS: 02.10.Gd, 03.65.Bz. This paper was a submission to the Fifth International Quantum Structure Association Conference (QS5), which took place in Cesena, Italy, March 31–April 5, 2001.     

电子横向运动对共振隧穿的影响

讨论了电子横纵方向运动耦合时的隧穿现象,对CdSe/Zn1-xCdxSe方形双势垒结构和抛物形双势垒结构的数值计算表明,在零偏压和非零偏压情况下,电子横向运动对共振隧穿的影响是不容忽略的。     

相对论电子束对波的相速的影响

在小信号情况下研究了相对论电子束对加速器微波相速的影响.首次提出了电子束流的介质等效的思想,并建立了等效的相对介电常数的计算公式.同时,建立了考虑小信号下相对论电子束的盘荷波导的简化色散方程.     

Synergetic Effects of Runaway Electron and Vertical Instability on the Wall Damage on HL-2A Tokamak

1 Generation of vertical instability Tokamak experiments show that the energy confinement time and performance are better, and the larger plasma current can be achieved for non-circular cross-sectional shape of plasma than circular cross-section. However, the external magnetic fields which are used to produce the non-circular cross sectional shape also cause the confined plasma to become unstable to small vertical displacement. In general, the ratio of elongation k is larger, the possibility of instability is more. In practice, this vertical displacement mode stabilized by feedback control system or other provided external radial magnetic field to balance out the plasma motion. Under some of situations the control system may be fail due to rapid growth rate of instability exceeding the ability of controlling. The plasma will then move vertically upwards or downwards depending upon the characteristics of instability and control failure.     

热晕小尺度不稳定性的研究

报道了在实验条件下热晕小尺度不稳定性的研究结果，从实验及数值模拟两方面给出了光束质量Ｓｔｒｅｈｌ比，扰动积分能量的增长，各扰动谱项的能量竞争以及近场光斑半径随时间的变化。研究结果基本反映了热晕小尺度不稳定性的物理规律，实验测量与数值的结果具有较好的一致性。     

Phase Transition of the Horava-Lifshitz AdS Black Holes

International Journal of Theoretical Physics - Some ones have showed the first-order phase transition of the Horava-Lifshitz (HL) AdS black holes has unique characters from other AdS black holes....     

Binding Energies of the Electron in GaAs-Gal-xAlxAs Quantum Well Under Perpendicular Magnetic Field

We have calculated the binding energies of the ground state of hydrogenic donor in GaAs-Ga_1-xAl_xAs quantum well of finite barrier height in the prcscnce of a magnetic field, which is taken to be parallel to the axis of growth of the quantum-well structure. We have used the strong-perturbation theory and the perturbative-variational approach. Our results are given as a function of the size of the quantum well.     

Phase Velocities of Modes Formed in the Process of SRS in Hollow Fibers

A numerical study of the phase velocities of collective modes of a hollow fiber at the Stokes frequency has been carried out. The effect of self-recovery of the transverse structure of a set of modes (Talbot effect) has been investigated. It has been shown that the sum of the longitudinal wave numbers of collective modes is constant with pump power. Presented at V International Scientific-Engineering Conference on Quantum Electronics, 22–25 November 2004, Minsk, Belarus. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 486–490, July–August, 2005.     

Dynamics of the Thermal Instability Evolution in Dielectric Breakdown

A mathematical model of the dynamics of temperature, electric field strength, and charge density in thermal dielectric breakdown is examined. The characteristics of the evolution of a thermal instability initiated by a local temperature disturbance are studied by numerical modeling. The conditions of initiation and growth of an electrothermal structure resulting in the formation of a highly conductive channel and shunting of the dielectrics current are identified.     

激光等离子体相互作用中自生磁场及其空间演化

利用粒子模拟程序,模拟研究了超强激光与等离子体相互作用中的电子束流不稳定性的产生机制,得到了不稳定性所激发的自生磁场的线性增长率与各向异性参数之间的函数关系。观察到了激光与等离子体相互作用时产生的饱和自生磁场在表面领域上的演化过程,发现沿x方向出现的电流比较大时,饱和自生的磁场在z方向的发展比较快,临界面附近较大,但随着深度的增加,逐渐以指数形式减少。     

Droplet-Laden Mist Film Cooling Effectiveness of Cylindrical Holes Embedded in a Transverse Trench

A three-dimensional numerical model of calculating in the Euler approach is developed to calculate a two-phase turbulent near-wall flow; simulation of thermal efficiency of a gas-droplet shielding injected into a transverse trench through inclined cylindrical holes is fulfilled. The influence of the main thermo-gas-dynamic characteristics of the two-phase flow on thermal efficiency is analyzed. Significant increase in thermal efficiency was obtained by adding droplets in the nearwall coolant flow (up to 2 times in comparison with a single-phase flow). A particular advantage of this method of coolant injection is achieved at high injection parameters. It is shown that the use of two-phase gas-droplet near-wall shielding is promising for protection of surfaces against thermal influence of the heated gas flows.