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Experiments have been performed on filling a stellarator with a noncurrent-carrying laser-produced plasma. Simultaneous plasma production by means of pulsed laser beams at four separate positions on the toroidal magnetic axis has been found to drastically enhance the trapping efficiency of produced plasma by stellarator field, to as high as 50 percent in contrast with about 10 percent in the case of plasma production at one position. This figure of 50 percent could be further improved to nearly 75 percent by spatially isotropic plasma productions which could not be realized in the present experiments owing to technical restrictions on the stellarator employed. The enhancement of trapping efficiency may be attributed to the reduction of toroidal plasma drift due to rotational transform coming into effect earlier in the multiposition production case. Some approximate theoretical analyses and considerations on toroidal drift motion of laser-produced plasma stream within stellarator field have also been presented, and the theoretical prediction on these analyses appears to be consistent with experimental results obtained. 相似文献
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激光辐射半圆柱凹槽靶产生等离子体特点 总被引:1,自引:0,他引:1
在利用激光产生的等离子体作为增益介质,实现X射线激光器的研究中,等离子体的密度分布形状及其时间演化起着重要作用,它不仅决定了等离子体中的原子分子过程,还决定了X射线的传输特性。在一般的软X射线自发辐射放大的实验里,如线聚焦激光辐照薄箔实验,在脉宽为数十微微秒,功率密度约为10~(14)W/cm~2的高功率激光照射下,产生的靶等离 相似文献
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An analytical formula for maximizing radiation efficiency from a laser-produced plasma is derived. The maximum efficiency is achieved when the plasma expansion distance during laser heating is equal to the laser absorption length. The dependence of the radiation efficiency on the plasma density is confirmed by experiments using a particle-cluster target. By creating a relatively uniform density plasma with a 300 microm diameter by dispersing SnO(2) particles coated on a Si wafer, the conversion efficiency at 14 nm, as high as 4 times as that for a Sn plate target, is achieved. 相似文献
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This review article describes apparatus for ion and X-ray diagnostics, which were used in experimental studies of laser-produced plasmas performed by the IPPLM's team in collaboration with other researchers at IPPLM and PALS Research Centre in Prague (the Czech Republic). The investigations of expanding laser-produced plasma properties in dependence on laser beam parameters were done by means of ion diagnostics devices: ion collectors (ICs), cylindrical ion energy analyzer (IEA) and the mass spectrograph of the Thomson type. At IPPLM, different types of detectors have been developed for measurement of X-ray emission. Properties of laser-produced beams of ions and X-ray radiation were analysed in the cooperative experiments performed with the use of a high-energy iodine laser PALS at the PALS Research Centre ASCR in the Czech Republic and the low-energy repetitive laser at IPPLM. 相似文献
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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-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. 相似文献
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The processes occurring in expanding laser-produced antimony plasma are investigated by the emission spectroscopy method.
The plasma expansion velocity, the recombination time of SbII, and the electron temperature and density are determined from
the dynamics of SbI line emission. Based on the results obtained, the processes occurring during the formation and expansion
of laser-produced antimony plasma are qualitatively analyzed. 相似文献
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A. Rousse K. Ta Phuoc R. Shah R. Fitour F. Albert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):391-398
Energetic electron beams accelerated in a laser-produced plasma wakefield cavity can generate collimated beams of X-ray radiation.
The oscillation of the electrons in the plasma cavity produces synchrotron-like emission, called betatron radiation. On the
basis of state of the art experiments, we discuss the potentiality of this source in terms of spectral brigthness and flux.
These characteristics are compared to existing and planned
X-ray sources in both laser and accelerator communities. 相似文献
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We report a measurement of the electron temperature in a plasma generated by a high-intensity laser focused into a jet of neon. The 15?eV electron temperature is determined using an analytic solution of the plasma equations assuming local thermodynamic equilibrium, initially developed for ultracold neutral plasmas. We show that this analysis method accurately reproduces more sophisticated plasma simulations in our temperature and density range. While our plasma temperatures are far outside the typical "ultracold" regime, the ion temperature is determined by the plasma density through disorder-induced heating just as in ultracold neutral plasma experiments. Based on our results, we outline a pathway for achieving a strongly coupled neutral laser-produced plasma that even more closely resembles ultracold neutral plasma conditions. 相似文献
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F.E. Irons 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,24(2):119-132
The conditions under which the escape factor technique may be used to describe photo-excitation within the individual components of an overlapping doublet with a common lower state are derived and are found to be violated in a differentially moving plasma such as a laser-produced plasma. Model calculations are presented for the hydrogen-like Lα doublet, which is currently of interest with laser-produced plasmas. 相似文献
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The spectra from laser-produced plasma have been simulated by the newly developed model. The simulation agrees well with the experimental results, which can prove that the K-shell model is suitable for the application of the spectrum from laser-produced plasma. Also, the jkl satellite lines were found important for predicting the spectra. 相似文献
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R. A. Ganeev 《Optics and Spectroscopy》2016,121(4):614-634
We review recent studies of the coherent phase matched conversion of ultrashort pulses in the modulated plasmas. Particularly, we discuss the influence of ablated and tunneled electrons on the quasiphase- matched high-order harmonic generation in laser-produced plasma and application of mid-infrared pulses for the quasi-phase-matching of harmonics in silver plasma. These studies demonstrate the perspectives of frequency conversion in properly modulated laser-produced plasmas. 相似文献
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Y. Guo 《Optics & Laser Technology》1995,27(6):375-378
In this paper, we present experiments of extreme ultraviolet (EUV) contact lithography based on a compact laser-produced plasma (LPP) and investigated the radiation of the plasma from Cu, Fe, W targets. We measured the depth of development of a polychlorinated methylstyrene (PCMS) resist exposed through a 100 I mm−1 Cu net for times ranging from 10 to 40 minutes using different targets. 相似文献
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Spatial-Resolved Measurement and Analysis of Extreme-Ultraviolet Emission Spectra from Laser-Produced Al Plasmas
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《中国物理快报》2016,(4)
Extreme ultraviolet emission from laser-produced A1 plasma is experimentally and theoretically investigated.Spatial-evolution emission spectra are measured by using the spatio-temporally resolved laser produced plasma technique.Based on the assumptions of a normalized Boltzmann distribution among the excited states and a steady-state collisional-radiative model,we succeed in reproducing the spectra at different detection positions,which are in good agreement with experiments.The decay curves about the electron temperature and electron density,as well as the fractions of individual A1 ions and average ionization stage with increasing the detection distance are obtained by comparison with the experimental measurements.These parameters are critical points for deeply understanding the expanding and cooling of laser produced plasmas in vacuum. 相似文献
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为了准确诊断激光等离子体的电子密度,提出了一种基于极化光谱的类氦共振线与互组合线相对强度比诊断电子密度的方法.该法考虑了激光等离子体发射的X射线存在极化的特性,用极化光谱理论对测量的类氦共振线和互组合线光谱相对强度比进行精密校正,再推导等离子体的电子密度.在2×10 J激光装置上进行了实验,使用极化PET(002)晶体谱仪测量了Al类氦离子光谱,利用光谱的极化特性推出Al等离子体的电子密度约为1.5×1020 cm-3.结果表明极化X光谱推导等离子体电子密度方法适合激光高温高密等离子体诊断. 相似文献
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Fujioka S Nishimura H Nishihara K Sasaki A Sunahara A Okuno T Ueda N Ando T Tao Y Shimada Y Hashimoto K Yamaura M Shigemori K Nakai M Nagai K Norimatsu T Nishikawa T Miyanaga N Izawa Y Mima K 《Physical review letters》2005,95(23):235004
Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses. 相似文献
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We investigate from a theoretical point of view the basic possibilities for the effect of ionizing radiation on the X-ray gain in recombining laser-produced plasmas, in particular with regard to recently performed experiments in which targets consisting of two different-material layers (double-layer targets) were used. We discuss an increase of the gain for the 3 2 transition in hydrogenic ions which is due to photoionization causing, mainly, a decrease of the Lyman- reabsorption and an increase of the population of higher levels. In our numerical simulations we consider single-material and double-layer targets, concentrating particularly on carbon and titanium. We obtain and discuss the time behaviour of the X-ray emission from the laser-produced plasma with regard to its application as pump radiation. 相似文献