- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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High Energy and Short Pulse Lasers || Phase Manipulation of Ultrashort Soft X-Ray Pulses by Reflective Gratings
摘要： In this chapter, we discuss the use of reflective diffraction gratings to manipulate the phase of ultrashort pulses in the extreme ultraviolet (XUV) and soft X-ray spectral regions. Gratings may be used to condition the spectral phase of ultrashort pulses, e.g., to compensate for the pulse chirp and compress the pulse, similarly to what is routinely realized for visible and infrared pulses. The chirped pulse amplification technique has been already proposed for soft X-ray free-electron laser radiation; however, it requires the use of a compressor to compensate for the pulse chirp and get closer to the Fourier limit. There are fundamental differences when operating the gratings at wavelengths shorter than ≈40 nm on a broad band: (a) the gratings are operated at grazing incidence; therefore, the optical design has to be consequently tailored to this peculiar geometry; (b) the grating efficiency is definitely lower; therefore, the number of diffractions has to be limited to two. We discuss the different configurations that can be applied to the realization of a grating stretcher/compressor.
关键词： extreme ultraviolet,soft X-ray optics,ultrafast optics,diffraction gratings,chirped pulse amplification
更新于2025-09-16 10:30:52
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Characterization of plasma emission in the 1-6?nm band from laser-irradiated cryogenic xenon targets
摘要： We present measurements from laser-produced plasmas generated using cryogenic Xe targets and quantify the emission characteristics in the soft x-ray region (1 to 6 nm). The system is based on a LN2-cooled rotating drum, which allows for a high repetition rate, and Nd:YAG laser systems with energies up to 325 mJ on-target with pulse lengths of 130 ps, 600 ps, or 6.5 ns. High resolution spectra are measured using a grazing incidence spectrometer, and we present the first quantitative conversion efficiency (CE) measurements for Xe in this range. Data show CE values up to ～1% at 6 nm and ～0.08% at 1.5 nm (for 2% bandwidth and 2π solid angle), and there are lower limits on the required laser intensities and energies on target to achieve these efficiencies. In addition, the emission spot size is directly measured at 2 nm (620 eV) using a point-projection slit imaging method, with optimized emission spot sizes of ～20 μm.
关键词： soft x-ray,laser-produced plasmas,conversion efficiency,emission spot size,cryogenic Xe targets
更新于2025-09-16 10:30:52
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High Energy and Short Pulse Lasers || Brilliance Improvement of a Laser-Produced Soft X-Ray Plasma
摘要： The brilliance of a laser-produced soft X-ray source is enhanced for gaseous target concepts. In contrast to solid or liquid target materials, these sources are clean and versatile but provide a comparably low conversion efficiency of laser energy into EUV and soft X-ray radiation. The basic idea is to induce supersonic effects in the gas jet, leading to a local increase of the particle density, and thus, to a larger number of possible emitters. Typically, the target gas is expanded into a vacuum environment and the density rapidly drops in all directions. In the present approach, a low pressure helium atmosphere is used to generate shock waves in the supersonic nozzle flow. Passing through these structures, the target gas is recompressed, and the particle density is raised. By focusing the laser beam into such regions, a higher number of gas atoms can be ionized resulting in a brighter and smaller plasma.
关键词： soft X-ray,supersonic jet,barrel shock,laser-produced plasma
更新于2025-09-16 10:30:52
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Holographic Materials and Optical Systems || Dynamic Imaging with X-ray Holography
摘要： X-ray holography is a type of coherent diffractive imaging where the phase information is physically encoded in the diffraction pattern by means of interference with a reference beam. The image of the diffracting specimen is obtained by a single Fourier transform of the interference pattern. X-ray holography is particularly well-suited for high resolution dynamic imaging because, intrinsically, the reconstructed image does not drift and the images show high contrast. Therefore, the motion of features between two images can be determined with a precision of better than 3 nm, as demonstrated recently. In this chapter, the technical aspects of X-ray holography are discussed from an end user perspective, focusing on what is required to obtain a high quality image in a short time. Specifically, the chapter discusses the key challenges of the technique, such as sample design and fabrication, beam requirements, suitable end stations, and how to implement pump-probe dynamic imaging. Good imaging parameters were found using simulations and experiments, and it is demonstrated how a deviation from the optimum value affects the image quality.
关键词： high resolution imaging,soft X-ray imaging,dynamic imaging,magnetic imaging,X-ray holography
更新于2025-09-12 10:27:22
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Spatial Characteristics of Thomson Scattering Spectra in Laser and Magnetic Fields
摘要： Spatial characteristics of Thomson scattering spectra are studied for an electron moving in the circularly polarized laser field in the presence of a strong uniform magnetic field. The results show that the angular distributions of the spectra with respect to the azimuthal and polar angles exhibit different symmetries, respectively, which depend on the fields and electron parameters sensitively and significantly. Moreover, for relatively large parameters such as high laser intensity, high magnetic resonance parameter as well as large initial momentum of electron, the two lobes in spectra tend to the laser-propagating direction so that the radiation can be collimated in the forward direction. Furthermore, an important finding is that by choosing the appropriate fields and initial momentum of electron, the high frequency part of the Thomson scattering spectra can reach the frequency range of soft x-ray, in which a high radiation power per solid angle as ～1011 a.u. can be obtained.
关键词： Thomson scattering,magnetic field,spatial characteristics,laser field,soft x-ray
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Theoretical Investigation of Resonant High-Harmonic Generation in Transition Metal Plasma
摘要： High-harmonic generation (HHG) is a promising tool for generating XUV and soft X-ray radiations using table-top experimental setup. Whereas the conversion efficiency of HHG is usually low, one alternative for increasing HH yield lies in the use of transition metal plasma as a generating medium, from which several resonantly enhanced harmonic peaks have been observed [1]. In this work, we numerically investigate HHG from transition metal elements. We use state-of-the-art all-electron first-principles simulation methods, TD-CASSCF and TD-ORMAS [2-4], which we have recently developed. The calculated harmonic spectra from Mn and its cation (“active 3p” in Fig. 1) exhibit an enhanced peak at 51 eV, successfully reproducing the experimental observations [5, 6]. The arrows in Fig. 1 mark the cutoff positions (cid:7)(cid:15) of the indicated ionic species predicted by the cutoff law, (cid:7)(cid:15) (cid:20) (cid:8)(cid:16) (cid:17) (cid:5)(cid:2)(cid:4)(cid:6)(cid:9)(cid:16), where (cid:8)(cid:16) and (cid:9)(cid:16) denote the ionization potential and ponderomotive energy, respectively. The extension of the cutoff beyond that corresponding to the starting ionic species indicates a significant production of higher ionic states, i.e., plasma. One of the advantages of our methods is that we can freeze the motion of given orbitals to get physical insights into the underlying mechanism. If we freeze the 3p orbitals, the enhanced peak disappears (“frozen 3p” in Fig. 1). This unambiguously demonstrates that the origin of the peak is the 3p-3d giant resonance, as implied by its position [5], and, thus, the manifestation of multielectron effects. Further, we have analyzed how each of the three 3p-3d transition lines ( (cid:10) (cid:20) (cid:18)(cid:4)(cid:1)(cid:3)(cid:21) contributes to the peak and revealed that they constructively interfere to form the enhanced peak at 51 eV.
关键词： High-harmonic generation,TD-CASSCF,soft X-ray,transition metal plasma,TD-ORMAS,XUV
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Attosecond Soft X-Ray Absorption Spectroscopy in Graphite
摘要： X-ray absorption fine-structure (XAFS) spectroscopy is a well-established technique capable to extract information on the electronic and lattice structure of a material with atomic resolution. Analysis of the XAFS spectrum in the near-edge region (XANES) provides information about the electronic configuration. Structural information is extracted from the extended XAFS (EXAFS) spectrum, consisting of several hundreds of eV above the absorption edge. Connecting the spectroscopic capabilities of XAFS technique to high temporal resolution would give the possibility to follow electronic and lattice dynamics in real time. Here, we present the simultaneously access to electronic and lattice parameters via XAFS spectroscopy using isolated attosecond soft X-ray (SXR) pulses covering the entire water window region (280 eV to 540 eV). We demonstrate the novel capabilities of attosecond XAFS (attoXAFS) by identifying the (cid:1)* and (cid:1)* orbital contributions to the density of states in highly oriented pyrolithic graphite (HOPG) simultaneously with the four characteristic bonding distances of graphite’s hexagonal lattice.
关键词： attosecond,graphite,soft X-ray,electronic and lattice dynamics,XAFS spectroscopy
更新于2025-09-11 14:15:04
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Present status of photoemission electron microscope newly installed in SPring-8 for time-resolved nanospectroscopy
摘要： A photoemission electron microscope (PEEM) system has been newly installed at the soft X-ray undulator beamline (BL17SU) of SPring-8 to realize time-resolved nanospectroscopy for the local transient electronic structures of advanced materials. This PEEM is a versatile machine composed of an electrostatic lens system and is intended for use in specific experiments such as time-resolved measurements. Pump–probe measurements in tandem with a femtosecond pulsed-laser system and an X-ray chopper are now readily available.
关键词： photoemission electron microscope,time-resolved nanospectroscopy,SPring-8,soft X-ray undulator beamline,PEEM
更新于2025-09-11 14:15:04
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A Monochromatic Soft X-ray Generation from Femtosecond Laser-produced Plasma with Aluminum
摘要： A tabletop ultrafast soft x-ray has been generated from the laser-produce plasma with a femtosecond pulsed Ti:Sapphire laser. The estimated total ?ux of Al Kα is of 2.2 × 109 photons/sec in 4π radian and the parameters related to the optical performance were obtained. The tungsten/silicon multilayer, ?at quartz and bent thallium acid phthalate (TLAP) crystal were used for monochromatization of soft x-ray to re?ne the aluminum Kα radiation and compared the respective value of E/ΔE. To estimate the size of the x-ray source beam generated by a fs laser, the approximation using the FWHM obtained from the x-ray beam scan near the focal point was discussed, and the size of the diameter was about 9.76 μm.
关键词： Monochromatic,Aluminum,Soft x-ray,XRD,Femtosecond laser
更新于2025-09-11 14:15:04
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A computational tool for simulation and design of tangential multi-energy soft x-ray pin-hole cameras for tokamak plasmas
摘要： A new tool has been developed to calculate the spectral, spatial, and temporal responses of multi-energy soft x-ray (ME-SXR) pinhole cameras for arbitrary plasma densities (ne,D), temperature (Te), and impurity densities (nZ). ME-SXR imaging provides a unique opportunity for obtaining important plasma properties (e.g., Te, nZ, and Z eff) by measuring both continuum and line emission in multiple energy ranges. This technique employs a pixelated x-ray detector in which the lower energy threshold for photon detection can be adjusted independently. Simulations assuming a tangential geometry and DIII-D-like plasmas (e.g., ne,0 ≈ 8 × 1019 m?3 and T e,0 ≈ 2.8 keV) for various impurity (e.g., C, O, Ar, Ni, and Mo) density pro?les have been performed. The computed brightnesses range from few 102 counts pixel?1 ms?1 depending on the cut-off energy thresholds, while the maximum allowable count rate is 104 counts pixel?1 ms?1. The typical spatial resolution in the mid-plane is ≈0.5 cm with a photon-energy resolution of 500 eV at a 500 Hz frame rate.
关键词： tokamak plasmas,multi-energy soft x-ray,plasma diagnostics,pinhole cameras,x-ray spectra
更新于2025-09-10 09:29:36