Charged particle energy analyzer based on a modified cylindrical mirror

A modified design of an electrostatic energy analyzer of the cylindrical mirror type is suggested. The outer electrode of the modified analyzer consists of three cylinders with equal radii and different potentials. The electron-optical properties of the analyzer are numerically simulated, and it is demonstrated that it may offer a much higher focusing quality than a conventional cylindrical mirror. Optimal design and operating conditions are found for which the spherical aberration decreases fivefold compared with the conventional mirror.     

Conical Mirror Energy-Analyzer

Electron optical properties of an axisymmetric mirror energy-analyzer are studied. The internal electrode represents a cylinder, and the external electrode is formed by two identical cones with common bases. It is shown that the relative aperture and resolution of such an analyzer are significantly greater than the corresponding parameters of a conventional cylindrical mirror. The internal electrode is made of three cylinders with different diameters, and the potentials of the cylinders are identical. Such a structure is used to further improve electron optical characteristics of the conical analyzer. At a relatively small beam angle, the resolution of the conical analyzer is two times greater than the resolution of the cylindrical mirror, and the difference of the resolutions amounts to an order of magnitude when the beam angle increases.

     

Focusing properties of a mirror analyzer with hexapole cylindrical field

In this work, motion of charged particles is studied in a new-type electrostatic field—the multiple cylindrical one, formed by superposition of electrostatic fields of a cylindrical mirror and a circular hexapole. On a base of the power-series analytical technique of solution of the equation of motion presented in integro-differential form, charged particle trajectories are calculated. Data on focusing properties of hexapole cylindrical mirror analyzer are obtained.     

Cylindrical mirror energy analyzer with the input of charged particles through end-surface diaphragm

Computer simulation is used to study electron-optical properties of a cylindrical mirror analyzer with the input of charged particles through the end-surface diaphragm. Regimes with double crossing of the optical axis (two-stage analyzer) are considered to increase the linear dispersion. The external electrode of the electron-optical system under study can be divided into several insulated parts with independently controlled potentials. Such an approach allows the second-order tuning of focusing and wide-range variation in the dispersion. Optimal working regimes make it possible to increase the linear dispersion by a factor of 3–4 in comparison with the one-stage regime.     

高次柱面反射型太阳能聚光镜的光学设计

提出了一种新型高效太阳能聚光镜, 这种聚光镜用一组特定系数, a₂, a₄, a₆, a₈, a₁₀, a₁₂, a₁₄, a₁₆ 与 C的高次柱面内壁的一部分作为反射镜. 利用高次柱面方程和光反射定律, 推导出了在高次柱面内壁上太阳反射光束的方向矢量与高次柱面系数C, a₂,a₄, a₆, a₈, a₁₀, a₁₂, a₁₄, a₁₆的关系, 通过优化设计这些系数, 可以使入射到高次柱面内壁上的太阳光束反射后全部聚焦在一条与柱面母线平行的宽度很窄的线段上, 形成线聚光. 这组特定系数用粒子群优化算法求得, 并经计算机模拟证明其聚焦效果. 用这组特定系数的高次柱面作为聚光镜, 其对光的压缩比可达148倍, 其线性光斑可作为一种强光源或高温光源. 高次柱面反射镜可由金属或玻璃直接磨制而成, 也可由高次柱面骨架和铺设在骨架上的镀铝聚酯薄膜构成. 关键词： 太阳能聚光镜 高次柱面 多项式系数优化 线性聚焦     

Photoelectron branching ratios with a cylindrical mirror energy analyzer

A cylindrical mirror photoelectron energy analyzer suitable for measuring photoelectron branching ratios is described. The analyzer incorporates a pre-retarding/ accelerating system. This configuration is shown to have advantages over a conventional mirror analyzer in reduced pressure-sensitive scattering effects which can effect the accuracy of the branching ratios, and in increased sensitivity to low energy electrons. The electron collecting efficiency of the analyzer for a number of operating modes is given.     

Improved cylindrical mirror energy analyzer

A study has been carried out of the electron-optical properties of improved design of the cylindrical mirror energy analyzer. Both external and internal electrodes of the analyzer are divided into three isolated parts, whereby the potentials on the individual parts can be regulated independently from each other. In symmetric operating mode at identical potentials on the side parts of the electrodes, a significant increase has been obtained in resolving power and light-gathering power of the analyzer compared to the standard design of the cylindrical mirror. In asymmetric operating mode, which is implemented in a linear potential distribution on the external electrode, the conditions have been found under which the linear dispersion of the analyzer increases several times.

     

Spherical analyzer with pre-retardation

The features of the spherical analyzer with and without pre-retardation are compared. The results are applicable to other types of spectrometers as, e.g., the cylindrical analyzer and the cylindrical mirror.     

Two-period cylindrical energy analyzer with end electrodes

Analytical expressions are obtained for the main parameters of a cylindrical analyzer with flat end electrodes held at the potential of the inner cylinder. Calculations are carried out for its one-and two-period operating regimes with first-order focusing with respect to angle for an object lying outside the analyzer. It is found that the greater the distance from the object to the front end of the analyzer, the smaller its focal power. The exit beam intensity is calculated for the situation in which the surface of the sample is scanned by the primary beam, and also for the case of an object of finite dimensions. Empirical formulas are found for the falloff of the intensity with distance from the center of the object. A comparison of numerical calculations using a program for two-dimensional charged-particle optics and calculations from our analytical formulas shows that their difference does not exceed 10%. Zh. Tekh. Fiz. 89–91 (August 1997)     

宽波段高分辨率改进型Czerny-Turner成像光谱仪研究

主要针对Czerny-Turner结构在成像光谱仪系统中的应用进行了研究。Czerny-Turner结构主要存在的像差为像散。为了获得了该结构的完善消像散条件,对其进行了理论分析和结构改进。系统的基本结构不变,仍由球面准直镜,平面光栅和球面聚焦镜组成,但在聚焦镜后添加了一个带楔角的柱面镜,该柱面镜解决了子午方向和弧矢方向上存在大像散差的问题,使系统可以在较宽的波段上实现较高的分辨率,同时元件制作成本大大降低。设计了一个工作在可见光波段(380~760 nm)的改进型成像光谱系统,并对设计理论进行了验证。例子成功设计了数值孔径0.05,全视场全波段调制传递函数值在奈奎斯特频率(20 lp·mm-1)下大于0.59的高分辨率成像光谱仪光学系统。这种改进的系统设计理论适用于小型宽波段高分辨率成像光谱仪。     

Synchrotron X‐ray tests of an L‐shaped laterally graded multilayer mirror for the analyzer system of the ultra‐high‐resolution IXS spectrometer at NSLS‐II

Characterization and testing of an L‐shaped laterally graded multilayer mirror are presented. This mirror is designed as a two‐dimensional collimating optics for the analyzer system of the ultra‐high‐resolution inelastic X‐ray scattering (IXS) spectrometer at National Synchrotron Light Source II (NSLS‐II). The characterization includes point‐to‐point reflectivity measurements, lattice parameter determination and mirror metrology (figure, slope error and roughness). The synchrotron X‐ray test of the mirror was carried out reversely as a focusing device. The results show that the L‐shaped laterally graded multilayer mirror is suitable to be used, with high efficiency, for the analyzer system of the IXS spectrometer at NSLS‐II.     

Application of Novel Focusing Mirrors in Gyrotron Transmission Lines

A novel focusing mirror based on the shifting of the beam phase according to the Gaussian beam optics enabled us to realize a focusing elements with different focal lengths in different directions and to convert the gyrotron output into a Gaussian-like beam. In this paper, we compare the quality of beams produced by the new system (which includes novel mirrors) and a conventional system consisting of a quasi-optical antenna, an ellipsoidal mirror and two parabolic cylinder mirrors.     

Orientation dependence of overlayer attenuation of electrons for the cylindrical mirror analyzer and a retarding field analyzer

The effect of a homogeneous flat overlayer in attenuating spectral lines is analyzed as a function of orientation for apertures corresponding to a 42.3° cylindrical mirror analyzer and 48° retarding field analyzer. Exponential attenuation with path length is assumed. Results are presented graphically for both isotropic and cosine distributions of sources. The numerical results are particularly useful when practical considerations require the use of an unsymmetrical sample orientation. The results are pertinent to measurements of inelastic mean free paths and are also related to the response of these spectrometers to different depth distributions of elements.     

Collecting efficiency of a cylindrical mirror electron energy analyzer with pre-retarding lens

The electron collecting efficiency of a cylindrical mirror energy analyzer incorporating retardation of the electrons prior to analysis has been determined over the range 0 to 30 eV by two methods. The first method requires the use of a vacuum ultraviolet monochromator to produce monoenergetic electrons of different energies; the second method involves measuring the energy-brightness relationship of the retarding optics and should be applicable to any deflection analyzer with pre-retarding optics. The results of the two methods are compared and the limitations of the latter method are discussed.     

带前置光学系统的软X射线透射光栅光谱仪

软Ｘ射线检测是激光等离子体诊断中最复杂而又是最重要的一项工作。本文简要介绍了带有前置光学系统的软Ｘ射线大面积透射光栅光谱仪和用它获得的铝和铜靶激光等离子体的光谱图。     

Relativistic effects in the calibration of electrostatic electron analyzers. II. Parallel plate and cylindrical mirror analyzers

Relativistic correction terms up to the second order are derived for the kinetic energy of an electron travelling along the central trajectory, which crosses the non-relativistic foci of electrostatic parallel plate and cylindrical mirror analyzers. The effects of fringing fields and source geometry are neglected. In both cases the magnitude of relativistic corrections depends on the geometry of the analyzer, but generally it is smaller than for the toroidal family of analyzers.     

A new electron spectrometer design:II

A novel charged particle energy analyzer of simple geometry is described. Expressions for the potential distribution and electric field components defined by the geometry are given. A raytrace program using these components is discussed and results of its application are presented in graphical and tabular form. Also presented are experimental results for two versions of the analyzer in the form of representative spectra of well known species (Ar⁺, H₂⁺, O₂⁺). Finally, a comparison of the new instrument with the well known cylindrical mirror analyzer is outlined which suggests the superiority of the new instrument under the specific conditions given.     

3-Dimensional Computer Simulation of Plasma Confinement in a Resonant RF Cavity Aided by a Magnetic Mirror: Single Particle Trajectories

The 3-dimensional trajectories of a single, charged particle within the fields of a resonant microwave cavity and a DC magnetic mirror were computed. The RF fields were due to the TM011 mode of a cylindrical cavity which produces a closed, 3-dimensional, axisymmetric containment region in the center of the cavity. The mirror field was produced by current carrying rings at the ends of the cylinder. The combined fields were able to contain particles which would escape the RF containment well alone. Similarly, the loss cone angles at the ends of the mirror were decreased, a result noted by Gray [1] for a mirror simulated by parabolic magnetic fields aided by a 1-dimensional RF containment well.     

Effect of counterions on the Rayleigh-Plateau instability of a charged cylinder

The effect of counterions on the instability of a charged cylinder is investigated. Both axisymmetric and asymmetric perturbations are considered. The analysis shows that the Rayleigh-Plateau instability is modified for a charged cylinder in the presence of counterions. For the axisymmetric instability, the counterions have a stabilizing effect at low values of k \kappa , the inverse Debye layer thickness. However, the effect is destabilizing at higher values of k \kappa . The asymmetric modes which are stable for an uncharged cylinder are rendered unstable at high values of k \kappa . The analysis should be important in pearling instability of charged cylindrical vesicles. The expression for the correlation time of thermally induced shape fluctuations of charged cylindrical vesicles is also derived.     

A beam divergence correction mirror for neutron resonance spin echo

Neutron resonance spin echo (NRSE) enables us to measure neutron quasi-elastic scattering with high energy resolution. Its energy resolution is limited by a path length variation due to the beam divergence. Neutron focusing technique using a neutron supermirror can be used to overcome this problem. To investigate the effect of a cylindrical mirror on the path length variation due to the beam divergence, MIEZE (modulation of intensity by zero effort) spin echo measurement was performed. The result demonstrated that the cylindrical mirror effectively corrects the path length variation and leads to high energy resolution as well as high intensity in NRSE and MIEZE measurement.