Characterization of the 46.9-nm soft X-ray laser beam from a capillary discharge

Barnwal, S.; Prasad, Y. B. S. R.; Nigam, S.; Aneesh, K.; Sharma, Manohar; Kushwaha, Reena; Tripathi, P. K.; Naik, P. A.; Chakera, J. A.; Navathe, C. P.; Gupta, P. D.

doi:10.1007/s00340-014-5812-3

Cited by 12 publications

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“…The experiments were conducted on the capillary discharge X-ray laser system [28] at RRCAT, Indore, India. The system consists of a 450-kV, 10-stage Marx bank as the highvoltage generator for charging a fast waterline capacitor which discharges into an argon (pre-ionized)-filled ceramic capillary, through a fast spark gap switch, delivering very fast current of few tens of kA in few tens of nanoseconds (dI/dt > 10 11 A/s).…”

Section: Description Of Capillary Discharge X-ray Laser Systemmentioning

confidence: 99%

“…The most successful example is the soft X-ray laser at 46.9 nm from argon plasma produced using the wavelength. We have successfully built a 46.9-nm soft X-ray laser in our laboratory and characterized its temporal, spatial and spectral properties [28]. The laser pulse has a width of ~1.2 ns (FWHM), divergence ~3.5 mrad and wavelength at 46.9 nm.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the rate of rise in discharge current on the output of a 46.9-nm soft X-ray laser based on capillary discharge

et al. 2016

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fast capillary discharge scheme, which has been demonstrated by several groups worldwide [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. This is based on collisional excitation pumping through a fast heating of the plasma. Such a soft X-ray laser has several applications in different areas of science and technology [16][17][18][19][20][21][22]. In fact, there exists a strong interest in extending the lasing wavelength toward shorter side. It is worth mentioning here that directed EUV emission has also been reported from discharge plasma at shorter wavelengths ranging from 12 to 16 nm [23]. Efforts are presently going on in this direction in various laboratories worldwide to demonstrate X-ray lasing at a wavelength of 13.4 nm in nitrogen z-pinch plasma using a capillary discharge system [24][25][26][27]. Unlike the 46.9-nm X-ray laser, this is based on recombination pumping scheme which requires fast heating of the plasma followed by fast cooling of the hot plasma. Whether it is collisional excitation pumping scheme or recombination pumping scheme, both require faster pumping of the plasma to achieve population inversion, which can be done using a fast current pulse having high rate of rise (dI/dt) to excite the plasma.The generation of X-ray laser through the fast capillary discharge scheme is based on passing a fast rising electrical current through a pre-ionized gas column in a ceramic capillary. The magnetic field generated by the discharge current exerts strong magnetic force acting radially inwards on the plasma column. As a result, the plasma column gets pinched to a highly ionized hot and dense column, which may have sufficient population of required ionization state for lasing under suitable conditions. With argon gas filled inside the capillary, Ar 8+ ions are the lasing species and collectively form the gain medium for X-ray laser at 46.9 nm. Collisional electron excitation of these ions creates population inversion between 3p 1 S 0 and 3s 1 P 1 energy levels, which leads to soft X-ray lasing at 46.9 nm Abstract The rate of rise in discharge current (dI/dt) is an important parameter in an X-ray laser pumped by fast capillary discharge. The effect of this parameter on the energy of an argon plasma-based 46.9-nm soft X-ray laser pulse has been experimentally studied. It was found that an X-ray laser pulse with ~2 μJ energy, which can be obtained at a discharge current of ~40 kA with dI/dt value of ~7.1 × 10 11 A/s, can also be obtained at a much lower peak current of ~26 kA if the quarter period (T/4) of the discharge current is made shorter to achieve a comparable dI/dt value. For a fixed T/4, the laser energy could be enhanced from 2 to 4 μJ for an increase in the dI/dt value from 7.1 × 10 11 to 1.3 × 10 12 A/s by increasing the peak current from 26 to 44 kA. It was also observed that for a fixed dI/dt, mere increase in the discharge current does not increase the laser energy.

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Section: Description Of Capillary Discharge X-ray Laser Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of the rate of rise in discharge current on the output of a 46.9-nm soft X-ray laser based on capillary discharge

et al. 2016

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

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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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“…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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Characterization of the 46.9-nm soft X-ray laser beam from a capillary discharge

Cited by 12 publications

References 43 publications

Effect of the rate of rise in discharge current on the output of a 46.9-nm soft X-ray laser based on capillary discharge

Effect of the rate of rise in discharge current on the output of a 46.9-nm soft X-ray laser based on capillary discharge

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

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

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