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High resolution X-ray spherically bent crystal spectrometer for laser-produced plasma diagnostics

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Chinese Optics Letters 2009年第1期7卷 92-94页

作者：肖沙里王洪建施军唐昶环刘慎业 The Key Laboratory of Optoelectronic Technology and System Ministry of EducationChongqing University Research Center of laser Fusion China Academy of Engineering Physics

A new high spectral resolution crystal spectrometer is designed to measure very low emissive X-ray spectra of laser-produced plasma in 0.5-0.9 nm range. A large open aperture （30 ×20 （mm）） mica （002） spherically bent crystal with curvature radius R = 380 mm is used as dispersive and focusing element. The imaging plate is employed to obtain high spectral resolution with effective area of 30 × 80 （mm）. The long designed path of the X-ray spectrometer beam is 980 mm from the source to the detector via the crystal. Experiment is carried out at a 20-J laser facility. X-ray spectra in an absolute intensity scale is obtained from Al laserproduced plasmas created by laser energy of 6.78 J. Samples of spectra obtained with spectral resolution of up to E/△E - 1500 are presented. The results clearly show that the device is good to diagnose laser high-density plasmas.

关键词： laser produced plasmas lasers Mica Plasma diagnostics plasmas Silicate minerals Spectral resolution Spectrometers Spectrometry X ray analysis X ray spectrographs X ray spectrometers

laser-produced plasma He-alpha source for pulse radiography

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Chinese Optics Letters 2009年第2期7卷 156-158页

作者：王瑞荣陈伟民毛楚生董佳钦傅思祖 The Key Laboratory of Optoelectronic Technology and System Ministry of EducationChongqing University State Key Laboratory of High Power laser and Physics Shanghai Institute of Laser PlasmaChina Academy of Engineering Physics

Through the use of time and space integrated kiloelectronvolt （keV） spectroscopy, we investigate the thermal emission of plasma, which produces strong line emission from the titanium K shell （He-a at 4.7 keV and H-α at 4.9 keV）, created by laser. In order to optimize the conversion efficiency enhancement on titanium foils, the experiment is conducted under a variety of laser-driven intensity conditions. The X-ray emission intensity at 4.7 keV is measured and compared with prediction. The experimental result demonstrates that the solid Ti target laser-produced plasma （LPP） source has X-ray emission at 4.7 keV, which are all generated from electronic transitions in Ti ions at pulse width of 2.1 ns or 30 ps, the crudely evaluated He-α X-ray intensity appears to slightly increase with laser intensity enhancement, and the pre- pulse effect increases the conversion efficiency of the He-α X-ray. In addition, a 90-μm-thick Ti foil as a filter is used to transmit He-α X-ray at near 4.7 keV, creating a quasi-monochromatic transmission and greatly reducing the lower- and higher-energy background.

关键词： Conversion efficiency Electromagnetic wave emission Emission spectroscopy Helium Ion beams laser produced plasmas lasers Plasma diagnostics Titanium X ray radiography X ray scattering X rays

High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma

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Chinese Optics Letters 2004年第8期2卷 495-496页

作者：肖沙里潘英俊钟先信熊先才杨国洪刘宗礼丁永坤 The Key Laboratory of Optoelectronic Technology and System Ministry of Education Chongqing University Chongqing 400044 Research Center of laser Fusion China Academy of Engineering Physics Mianyang 621900 Research Center of laser Fusion China Academy of Engineering Physics Mianyang 621900he X-ray spectrum emitted from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-ⅡFacility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP LIF PET and MICA curved crystal analyzers are described and the spectra of Au Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

The X-ray spectrum emitted, from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-Ⅱ Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

关键词： Crystals Iron laser produced plasmas X ray spectrographs X ray spectrometers X ray spectroscopy

Stability analysis of linearly chirped Gaussian pulse stacking in laser plasma reaction

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Chinese Optics Letters 2010年第2期8卷 248-252页

作者：郑欢王安廷许立新高昆明海 Institute of Photonics Department of PhysicsUniversity of Science and Technology of China

We analyze the stability of linearly chirped Gaussian pulse stacking （LCGPS） in the laser plasma reaction （LPR） in the inertial confinement fusion （ICF） system. The LPR can be treated as the process that the stacked pulse is first intensity filtered and then induces the plasma due to the thermalization time of the plasma. We also examine the stability of LCGPS over the change of the thermalization time of the plasma, the timing delay, and the intensity attenuation of the stacked pulse in the LPR, and compare the results with those of none chirped Gaussian pulse stacking （NCGPS）. Our results show that LCGPS is more stable than NCGPS.

关键词： Inertial confinement fusion laser beams laser produced plasmas Plasma interactions Pulsed laser applications System stability

Frequency spectrum characterization of terahertz emission from laser-induced air plasma

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Chinese Optics Letters 2014年第8期12卷 96-98页

作者：赵骥张亮亮骆怡蔓吴同张存林赵跃进 Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology School of Optoelectronics Beijing Institute of Technology Beijing Key Laboratory for Terahertz Spectroscopy and Imaging Key Laboratory of Terahertz OptoelectronicsMinistry of EducationCapital Normal University

Terahertz （THz） emission from laser-induced air-plasma is presented. The frequency spectra of THz wave are investigated using an air-biased-coherent-detection method. The frequency spectra are measured under different pump-pulse and probe-pulse energies. The frequency pump power and we speculate it caused by collision behavior spectra become narrow with the increasing Meanwhile, the bandwidth of the frequency spectra is broadened by the increasing probe power, which can be explained by pulse compression. Based on this finding, the optimal frequency spectrum of THz can be achieved by regulating the probe and pump beam.

关键词： Bandwidth compression laser produced plasmas Optical pumping Probes Spectroscopy Terahertz waves

Nickel-Like Samarium 4d- 4p X-Ray laser Gain in laser plasmas

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Chinese Physics Letters 2004年第9期21卷 1780-1782页

作者：董国轩曾交龙 DepartmentofMathematicalandPhysicalSciences NationalNaturalScienceFoundationofChinaBeijing100085 NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012

Populations of the 249 levels belonging to the ground configuration 3s23p63d10 and those of single excitations of a 3d,3p or 3s electron to the orbitals of n = 4 and 5 have been calculated for nickel-like samarium at temperatures from 300 to 1600eV and at densities from 1020 to 1022cm−3. The gain coefficients for possible x-ray laser lines are also determined under these plasma conditions. The possible laser lines are transitions from levels (3d3/2−14d3/2)0 and (3d5/2−14d5/2)0 to levels (3d3/2−14p1/2)1, (3d5/2−14p3/2)1 and (3d3/2−14p3/2)1. The favourable plasma condition for x-ray lasers is at the temperature of about 800eV and at the density of approximately 5.0×1021cm−3.

关键词： laser produced plasmas

L—Shell Absorption Spectrum Measurement and Simulation of the Mg laser Plasma

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Chinese Physics Letters 2002年第3期19卷 362-364页

作者：刘红杰张保汉等 ResearchCenteroflaserFusion ChinaAcademyofEngineeringPhysicsMianyang621900

We report on the measurement of the L-shell absorption spectrum of Mg laser plasma. The resonance absorption lines of Li-like and Be-like ions are clearly observed. The electron density is sufficiently high so that our sample plasma is in nearly complete local thermodynamic equilibrium. At the determined electron temperature 56±4eV and mass density 0.01±0.002g/cm3, the predicted transmission spectrum is calculated. The simulation result is in good agreement with the experiment.

关键词： laser produced plasmas

Using fence pulses to suppress stimulated Raman scattering effect in laser–plasma interaction

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Chinese Optics Letters 2014年第9期12卷 92-95页

作者：周煜梁隋展耿远超许立新明海 Department of Optics and Optical Engineering University of Science and Technology of China Research Center of laser Fusion China Academy of Engineering Physics

In inertial confinement fusion, the laser plasma interaction （LPI） happens when the high-energy laser irradi- ates on the target where the scattered light share generated from the stimulated Raman scattering （SRS） effect is difficult to suppress. We propose a method using fence pulses （FPs） to suppress the backward SRS by inhibiting the growth of the intensity of electron plasma waves. Based on our simulation, the FPs can weaken SRS effect in the LPI effectively.

关键词： Beam plasma interactions Fences High energy lasers laser beams laser fusion laser produced plasmas Wave plasma interactions

A four-channel multilayer KB microscope for high-resolution 8-keV X-ray imaging in laser-plasma diagnostics

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Chinese Optics Letters 2014年第1期12卷 79-82页

作者：伊圣振穆宝忠王新朱京涛蒋励王占山贺鹏飞 Key Laboratory of Advanced Micro-structured Materials (MOE) Tongji University School of Physics Sciences and Engineering Tongji University School of Aerospace Engineering and Applied Mechanics Tongji University

A four-channel multilayer Kirkpatrick-Baez （KB） microscope is developed for the 8-keV X-ray imaging of experiments on laser inertial confinement fusion （ICF）. A periodic multilayer that works at 8 keV and with a grazing incidence angle of 1.0~ is coated on reflective surfaces to achieve a spatial resolution higher than 5μm and an effective solid angle higher than 10-7 sr. A precise assembly is realized by a conical reference cone to couple with an X-ray framing camera. This study provides detailed information on an optical and multilayer design, assembly method, and experimental results with a Cu X-ray tube. The instrument provides a high-resolution and high-throughput X-ray image for backlit or self-emission imaging of laser plasma at Cu Kα line radiation in Shenguang series laser facilities.

关键词： Inertial confinement fusion laser produced plasmas Plasma diagnostics Plasma interactions X ray analysis