Influence of the gain-length product on the pulse duration of highly saturated capillary discharge soft X-ray laser

Zhao, Yijun; Jiang, Shan; Cui, Huaiyu; Li, Lianbo; Zhang, Wenhong; Li, Wei

doi:10.1007/s00340-015-6204-z

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…The system has now been emerged as a very compact table-top coherent x-ray source reliably working at few Hz repetition rate [11][12][13]. Several research groups worldwide have contributed to the progress of this field and the field still continues to grow even two decades after its first experimental demonstration [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. These groups have not only demonstrated the x-ray lasing under different exper imental conditions but also helped in understanding the role of various experimental parameters on the lasing action [20,22,29,30,31].…”

Section: Introductionmentioning

confidence: 99%

Impact of discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser

et al. 2017

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The very important role played by the discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser has been experimentally established. The discharge current profile was varied either by making the current faster and keeping its peak value fixed or by increasing its peak value and keeping the duration fixed. When the dI/dt value was increased from 7.5 × 10 11 to 9.2 × 10 11 A s −1 by making the current faster, the soft x-ray laser efficiency was found to be enhanced significantly. This was reflected by a substantial increase (~48%) in the gain-coefficient of the x-ray laser from 0.69 cm −1 to 1.02 cm −1 respectively. The effect of current amplitude on the gain-coefficient was also studied by measuring the gaincoefficient for different current amplitudes while keeping the duration fixed. It was found that there exists an optimum value of discharge current amplitude at which the gain-coefficient becomes maximum. Using such optimization, the gain-coefficient could be further enhanced to 1.33 cm −1 which is ~93% higher than the earlier value of 0.69 cm −1 .

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Section: Introductionmentioning

confidence: 99%

Impact of discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser

et al. 2017

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“…Other groups also had developed 46.9 nm laser pumped by capillary discharge [8][9][10][11][12][13][14][15][16]. Some groups studied the 46.9 nm laser with a low current, which is benefit to reduce the size and enhance the repetitive frequency of the laser.…”

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confidence: 95%

“…A population inversion between 2p 5 3p 1 S 0 and 2p 5 3s 1 P 1 (J = 0-1) in the Ne-like Ar ions was produced by the electron collisional excitation, and the gain coefficient at 46.9 nm (A line) was measured as 0.6 cm −1 . A saturated Ne-like Ar soft X-ray laser at 46.9 nm pumped by capillary discharge has produced millijoule-level laser pulses at a repetition rate of 4 Hz [2] and has led to many applications such as the diagnostics of dense plasma [3], lithography [4], nanoimaging [5], nanomachining [6] and material ablation [7].Other groups also had developed 46.9 nm laser pumped by capillary discharge [8][9][10][11][12][13][14][15][16]. Some groups studied the 46.9 nm laser with a low current, which is benefit to reduce the size and enhance the repetitive frequency of the laser.…”

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confidence: 99%

Characteristics of a multi-wavelength Ne-like Ar laser excited by capillary discharge

et al. 2016

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other applications. In 1994, J. J. Rocca et al. reported the first demonstration of large soft X-ray amplification in the plasma of a capillary discharge [1]. A population inversion between 2p 5 3p 1 S 0 and 2p 5 3s 1 P 1 (J = 0-1) in the Ne-like Ar ions was produced by the electron collisional excitation, and the gain coefficient at 46.9 nm (A line) was measured as 0.6 cm −1 . A saturated Ne-like Ar soft X-ray laser at 46.9 nm pumped by capillary discharge has produced millijoule-level laser pulses at a repetition rate of 4 Hz [2] and has led to many applications such as the diagnostics of dense plasma [3], lithography [4], nanoimaging [5], nanomachining [6] and material ablation [7].Other groups also had developed 46.9 nm laser pumped by capillary discharge [8][9][10][11][12][13][14][15][16]. Some groups studied the 46.9 nm laser with a low current, which is benefit to reduce the size and enhance the repetitive frequency of the laser. G. Niimi et al. firstly reported the observation of 46.9 nm laser output at a low discharge current of 9 kA [8]. G. Tomassetti et al. reported that 46.9 nm laser was realized with low amplitude 17-20 kA current pulses at pulse repetition rate up to 0.1 Hz [9]. The saturated laser at 46.9 nm was achieved by C. A. Tan et al. using the main current as low as 16 kA [13]. However, the other Ne-like Ar lasers were not observed by these groups.Except for J = 0-1 transition at 46.9 nm, EUV lasers can also be expected on some other 3p-3s transitions of Ne-like Ar in principle. The populations and gain coefficients of the 3p-3s transitions in Ne-like Ar were investigated by D. E. Kim et al. in theory [17]. It was found that large gains on the 3p 1 S 0 -3s 1 P 1 (J = 0-1), 3p 3 P 2 -3s 1 P 1 (J = 2-1) and 3p 3 D 2 -3s 3 P 1 (J = 2-1) transitions were formed for the electron density between 10 18 and 10 19 cm −3 . Due to the observation of intense laser on 3p 1 S 0 -3s 1 P 1 (J = 0-1) transition at 46.9 nm (A line), the two other lasers on 3p 3 P 2 -3s 1 P 1 (J = 2-1) transition at 69.8 nm (C line) and 3pAbstract We report the characteristics of 46.9, 69.8 and 72.6 nm lasers of Ne-like Ar in a plasma column pumped by capillary discharge. A main current of 12 kA with rise time of 40 ns was used to generate the plasma in a 35-cmlong capillary. The temporal and spatial characteristics of 46.9 and 69.8 nm laser pulses were measured. The time of lasing onset for the two lasers is about 35 ns. The pulse widths are about 1.3 ns for 46.9 nm laser and 1.2 ns for 69.8 nm laser. The FWHM beam divergences of the 46.9 and 69.8 nm lasers are approximately 0.5 and 0.4 mrad, respectively. The initial pressure ranges for 46.9, 69.8 and 72.6 nm lasers correspond to 13-24, 12.5-20 and 14-20 Pa, respectively. A gain coefficient of 0.58 cm −1 was measured and gain saturation behavior was observed at 46.9 nm, conditioning the initial pressure of 19 Pa. At the same discharge current, a 69.8 nm laser with gain coefficient of 0.41 cm −1 and a 72.6 nm laser with gain coefficient of 0.22 cm −1 were achieved by changing...

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A Simplified MHD Model of Capillary Z‐Pinch Compared with Experiments

Shapolov

Kiss

Kukhlevsky

2016

Contrib. Plasma Phys.

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The most accurate models of the capillary Z-pinches used for excitation of soft X-ray lasers and photolithography XUV sources currently are based on the magnetohydrodynamics theory (MHD). The output of MHD-based models greatly depends on details in the mathematical description, such as initial and boundary conditions, approximations of plasma parameters, etc. Small experimental groups who develop soft X-ray/XUV sources often use the simplest Z-pinch models for analysis of their experimental results, despite of these models are inconsistent with the MHD equations. In the present study, keeping only the essential terms in the MHD equations, we obtained a simplified MHD model of cylindrically symmetric capillary Z-pinch. The model gives accurate results compared to experiments with argon plasmas, and provides simple analysis of temporal evolution of main plasma parameters. The results clarify the influence of viscosity, heat flux and approximations of plasma conductivity on the dynamics of capillary Z-pinch plasmas. The model can be useful for researchers, especially experimentalists, who develop the soft X-ray/XUV sources.

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Influence of the gain-length product on the pulse duration of highly saturated capillary discharge soft X-ray laser

Cited by 6 publications

References 21 publications

Impact of discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser

Impact of discharge current profile on the lasing efficiency of 46.9 nm capillary discharge soft x-ray laser

Characteristics of a multi-wavelength Ne-like Ar laser excited by capillary discharge

A Simplified MHD Model of Capillary Z‐Pinch Compared with Experiments

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