Light-controlled pulsed x-ray tube with photocathode

Unstable mechanical structure, low energy efficiency, and cooling requirements limit the application of conventional x-ray tubes based on filament as cathode in several academic areas. In this paper, we demonstrate a light-controlled pulsed x-ray tube using multialkali cathode as electron generator. The photocathode active area of the light controlled x-ray tube is 13.2 cm² (41 mm in diameter), which provides high photoelectron-emitting efficiency up to 0.288 mA/lm in 460-nm LED and 2.37-mA maximum tube current. Furthermore, the modulation ability from 1 kHz to 100 kHz of the x-ray tube is tested. The results suggest that the light-controlled pulsed x-ray tube has easy modulation and short x-ray pulse properties and is promising to be the next generation x-ray tube with wide applications in medical radiation therapy as well as the calibration for detectors and scintillators.     

Focusing high-energy x-rays by a PMMA compound x-ray lens on Beijing synchrotron radiation facility

The x-ray compound lens is a novel refractive x-ray optical device. This paper reports the authors' recent research on a polymethyl methacrylate (PMMA) compound x-ray lens. Firstly the designing and LIGA fabrication process for the PMMA compound x-ray lens are briefly described. Then, a method for theoretical analysis, as well as the experimental system for measurement is also introduced. Finally, the focusing spots for 8keV monochromatic x-rays by the PMMA compound x-ray lens are measured and analysed. According to the experimental results, it is concluded that the PMMA compound x-ray lens promises a good focusing performance under the high-energy x-rays.     

X射线全息术

本文介绍了Ｘ射线全息术的工作原理和进展状况,详细地论述了与Ｘ射线全息术有关的Ｘ射线光学、Ｘ射线光学元件和Ｘ射线源的特性,并讨论了Ｘ射线全息实验的要求和记录方式,最后着重探讨了包括记录过程和重现过程中影响Ｘ射线全息术分辨率的各种因素。     

Ultrafast x-ray pulses emitted from a liquid mercury laser target

We report the generation of ultrashort, hard-x-ray pulses from a liquid mercury target irradiated by 5 kHz laser pulses. The new x-ray source is designed for time-resolved x-ray absorption spectroscopy as well as imaging applications. This marks the first laser-driven plasma x-ray source that continuously recycles the target material, facilitating maintenance-free operation. Theoretical calculations show mercury targets emit shorter x-ray pulses than targets of lighter elements under identical illumination and x-ray detection conditions.     

An x-ray biplanar photodiode and the x-ray emission from magnetically confined laser produced plasma

Development of a single and multichannel biplanar vacuum photodiode for x-ray detection is reported, which has been used to study the x-ray emission from laser produced plasma expanding across an externally applied magnetic field. Two to three times enhancement in x-ray emission has been observed which was found correlated with decrease in size of the x-ray emitting plasma plume (expansion velocity of plasma). Experimental observations were found in close agreement with the analytical model based on an increase in plasma density as a result of plasma confinement in magnetic field. Temporal evolution of x-ray emission indicates that recombination radiation seems to be playing an important role in x-ray enhancement.     

微束斑X射线源及X射线光学元件

高质量的X射线源,尤其高亮度的微纳束斑X射线源是现代X射线光学高清晰成像最为关键的部件之一,在工业无损探伤、生命科学、材料科学等科学研究和实际应用中具有重要的意义。简单介绍了微束斑X射线源的产生方法及发展历史,并对微束X射线光学涉及到的聚焦X射线光学元件（如X射线掠入射反射镜、布拉格法反射镜、多层膜反射镜、多层膜光栅、X射线波带片、毛细管聚焦透镜和复合折射透镜等）的主要特点作了简要的系统介绍。最后展望了微细束X射线在微纳检测与分析等方面的应用前景。     

Refractive microlens array for wave-front analysis in the medium to hard x-ray range

We report an alternative approach to x-ray wave-front analysis that uses a refractive microlens array as a Shack-Hartmann sensor. The sensor was manufactured by self-assembly and electroplating techniques and is suitable for high-resolution wave-front analysis of medium to hard x rays. We demonstrate its effectiveness at an x-ray energy of 3 keV for analysis of x-ray wave-front perturbations caused by microscopic objects. The sensor has potential advantages over other methods for x-ray phase imaging and will also be useful for the characterization of x-ray beams and optics.     

Upgrading design of the 3B1A beamline for x-ray nanometre lithography of microelectronic devices at BSRF

Beijing Synchrotron Radiation Facility is a partly dedicated synchrotron radiation source operated in either parasitic or dedicated mode. The 3B1A beamline, extracted from a bending magnet, was originally designed as a soft x-ray beamline for submicro x-ray lithography with critical lateral size just below 1μm in 1988 and no change has been made since it was built. But later the required resolution of x-ray lithography has changed from sub-micrometre to the nanometre in the critical lateral size. This beamline can longer more meet the requirement for x-ray nano lithography and has to be modified to fit the purpose. To upgrade the design of the 3B1A beamline for x-ray nano lithography, a mirror is used to reflect and scan the x-ray beam for the nano lithography station, but the mirror's grazing angle is changed to 27.9mrad in the vertical direction, and the convex curve needs to be modified to fit the change; the tiny change of mirror scanning angle is firstly considered to improve the uniformity of the x-ray spot on the wafer by controlling the convex curve.     

X-ray focusing using an x-ray lens composed of multi-square polycapillary slices

A new type of x-ray lens composed of multi-square polycapillary slices(ASPXRL)used in focusing parallel x-ray beam was presented in this paper.Compared with conventional x-ray polycapillary lens,ASPXRL can provide smaller and brighter focus.The effects of the manufacturing imperfections on focusing quality of ASPXRL were evaluated with the values of transmission efficiency and discussed.It is suggested that ASPXRL has application prospects as a condenser lens for x-ray microscopy and flux collectors for x-ray analytical instruments.     

Design of Grazing-Incidence Broad-Band Multilayers for Hard X-Ray Reflectors

A new method of designing x-ray supermirrors with broad angular or energy response for use as coatings in x-ray optics is presented. The design is based on an analytical method with oversimplified analytical and semi-empirical formulae, and an extensive numerical method is used in the optimization design. A better initial multilayer is obtained with the former method and optimized with the latter method. In the optimization, a good design is achieved with much less computing time. In addition, the saturation effect due to the interfacial roughness in multilayer also emerges in the design of x-ray supermirrors with definite performances. The reflectivity of C/W x-ray supermirrors as a function of photon energy at the fixed grazing incident angle 0.5°is presented.     

Unveiling and driving hidden resonances with high-fluence, high-intensity x-ray pulses

We show that high fluence, high-intensity x-ray pulses from the world's first hard x-ray free-electron laser produce nonlinear phenomena that differ dramatically from the linear x-ray-matter interaction processes that are encountered at synchrotron x-ray sources. We use intense x-ray pulses of sub-10-fs duration to first reveal and subsequently drive the 1s?2p resonance in singly ionized neon. This photon-driven cycling of an inner-shell electron modifies the Auger decay process, as evidenced by line shape modification. Our work demonstrates the propensity of high-fluence, femtosecond x-ray pulses to alter the target within a single pulse, i.e., to unveil hidden resonances, by cracking open inner shells energetically inaccessible via single-photon absorption, and to consequently trigger damaging electron cascades at unexpectedly low photon energies.     

Self-phase-matched high harmonic generation

Our theoretical analysis reveals that tunnel ionization significantly modifies the electric field of few-cycle laser pulses within a single oscillation period. This subcycle self-modulation is predicted to result in phase matching, making high harmonic generation in the x-ray regime possible for the first time. Such a radiation source opens novel possibilities in the investigation of matter with x-ray techniques, such as time resolved x-ray diffraction and absorption.     

Experimental study of conversion from atomic high—order harmonics to x—ray emissions

There are two physical phenomena in a strong laser intensity. One is the high-order harmonic emission; the other is x-ray emission from optical-field ionized plasmas. The experiment of conversion from high-order harmonics to x-ray emissions was given with a 105fs Ti:sapphire laser by adjusting laser intensities. The ingredient in plasma was investigated by the numerical simulations.Our experimental results suggested that the free electrons have detrimental effects on harmonic generation but are favourable for x-ray emission from optical-field ionized plasmas. If we want to obtain more intense harmonic signals as a coherent light source in the soft x-ray region, we must avoid the production of free electrons in plasmas. At the same time, if we want to observe x-rays for the development of high-repetition-rate table-top soft x-ray lasers, we should strip all atoms in the plasmas to a necessary ionized stage by the optical-field-ionization in the field of a high-intensity laser pulse.     

Electron density characterization by use of a broadband x-ray-compatible wave-front sensor

The use of a Hartmann wave-front sensor to accurately measure the line-integrated electron density gradients formed in laser-produced and z-pinch plasma experiments is examined. This wave-front sensor may be used with a soft-x-ray laser as well as with incoherent line emission at multikilovolt x-ray energies. This diagnostic is significantly easier to use than interferometery and moiré deflectometry, both of which have been demonstrated with soft-x-ray lasers. This scheme is experimentally demonstrated in the visible region by use of a Shack-Hartmann wave-front sensor and a liquid-crystal spatial light modulator to simulate a phase profile that could occur when an x-ray probe passes through a plasma. The merits of using a Hartmann sensor include a wide dynamic range, broadband or low-coherence-length light capability, high x-ray efficiency, two-dimensional gradient determination, multiplexing capability, and experimental simplicity. Hartmann sensors could also be utilized for wavelength testing of extreme-ultraviolet lithography components and x-ray phase imaging of biological specimens.     

A study of symmetrical LLL X-Ray polylithic interferometers on the basis of the Takagi equations

The Takagi approach to the dynamical theory of x-ray diffraction has been used to study LLL x-ray polylithic interferometers. A computational tool has been implemented to solve the Takagi equations with boundary conditions of the Cauchy type. The mean intensity, visibility and initial phase of the x-ray fringes generated by displacing the analyzer have been calculated for any wavefront, absorption of the incident radiation and for the most common geometric arrangements. Geometric aberrations of different kinds, introduced during interferometer preparation, are considered. The curve relevant to the calculated difference between the reflected and transmitted x-ray fringes as a function of analyzer rotation is in agreement with the experimental curve.     

Scanning LLL x-ray interferometry

A new formalism is presented for the theory of scanning LLL x-ray interferometry, which takes account also of the amount of x-ray absorption and of crystal yawing. It is based on the Takagi approach to the dynamical theory of x-ray diffraction and uses, to a great extent, the formalism of quantum mechanics, in order to reduce the algebraic complexity of the Ewald-von Laue approach. The formalism presented here is an easy-to-handle tool for the study of x-ray propagation in multicrystal systems and for the investigation into deviations of the travelling-fringe period from the spacing of diffracting planes, as it explains how interference features change when moving in paramater space.     

Modification of gravitational redshift of x-ray burst produced by pulsar surface magnetoplasma

In this paper, the propagation of x-ray bursts in the magnetoplasma of pulsar magnetosphere is discussed. The electromagnetic interaction between x-ray bursts and magnetoplasma is described as some geometry. The electromagnetic effects of surface superstrong magnetic field and dynamic effects of outflowing magnetoplasma of pulsars are treated as an optical metric. The Gordon metric is introduced to represent the gravitational metric and optical metric. So the propagation of x-ray bursts in magnetoplasma of pulsars can be described as x-ray bursts transmitting in an effective space characterized by Gordon metric. The modification of gravitational redshift, attributed to the flowing magnetoplasma of pulsars, is obtained and it is shown that the modification is of redshift and can reach the same magnitude as the gravitational redshift for ordinary pulsars.     

Deducing the electron-beam diameter in a laser-plasma accelerator using x-ray betatron radiation

We investigate the properties of a laser-plasma electron accelerator as a bright source of keV x-ray radiation. During the interaction, the electrons undergo betatron oscillations and from the carefully measured x-ray spectrum the oscillation amplitude of the electrons can be deduced which decreases with increasing electron energies. From the oscillation amplitude and the independently measured x-ray source size of (1.8±0.3) μm we are able to estimate the electron bunch diameter to be (1.6±0.3) μm.     

某些类氖离子和类镍离子等离子体状态对应关系的研究

利用一维拉格朗日流体动力学程序Med103详细研究了产生类镍Ag,Cd,In,Sn, Sb离子和类氖Fe,Co,Ni,Cu,Zn离子的等离子体状态.通过对电子温度、离子丰度、离子数密度等状态参量的分析比较，得到了这两类等离子体状态之间的对应关系.即类镍银的等离子体状态与类氖铁 的相近，类镍镉的与类氖钴的相近，依次类推.利用这一对应关系可以方便地由类氖机理x射线激光的等离子体状态来对相应元素的类镍x射线激光的等离子体状态进行判断. 关键词： 类氖 类镍 等离子体状态 x射线激光     

Modification of gravitational redshift of x-ray burst produced by pulsar surface magnetoplasma

In this paper, the propagation of x-ray bursts in the magnetoplasma of pulsar magnetosphere is discussed. The electromagnetic interaction between x-ray bursts and magnetoplasma is described as some geometry. The electromagnetic effects of surface superstrong magnetic field and dynamic effects of outflowing magnetoplasma of pulsars are treated as an optical metric. The Gordon metric is introduced to represent the gravitational metric and optical metric. So the propagation of x-ray bursts in magnetoplasma of pulsars can be described as x-ray bursts transmitting in an effective space characterized by Gordon metric. The modification of gravitational redshift, attributed to the flowing magnetoplasma of pulsars, is obtained and it is shown that the modification is of redshift and can reach the same magnitude as the gravitational redshift for ordinary pulsars.