Effect of nonequilibrium ionization process on gain of neon-like argon x-ray laser

Masnavi, Majid; Nakajima, Mitsuo; Horioka, Kazuhiko

doi:10.1063/1.1633986

Cited by 8 publications

(5 citation statements)

References 27 publications

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“…Apart from this, the gain of such collisionally pumped X-ray laser is significantly affected by the relaxation processes of different ionization states. A faster pumping of the gain medium can suppress these relaxation processes and can lead to higher gain [33]. This fast pumping can be achieved by delivering faster discharge current through the plasma.…”

Section: Resultsmentioning

confidence: 98%

“…Even for an ideal fast discharge current, there will be an upper limit on its dI/ dt value as long as the laser output is concerned. This is due to the fact that the gain dynamics of such highly non-equilibrium discharge plasma is governed by the ionization and relaxation processes during the thermalization of the shock implosion which have their own timescales [33].…”

Section: Resultsmentioning

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: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

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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“…Because the time scale of the ionization relaxation for the Ne-like Ar laser is comparable to that of the hydrodynamics of the pinch plasma, it is possible to enhance the intensity of lasing by reducing the mismatch. 27) Appendix B: Controlling Parameters for Laser Operation…”

Section: Appendix A: Plasma Dynamical Effects On Laser Operationmentioning

confidence: 99%

Effects of Plasma Dynamics on Lasing in Fast Capillary Discharge

Sakamoto

Masnavi

Nakajima

et al. 2008

jjap

Self Cite

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The timing, intensity, and pulse width of lasing signals in fast capillary discharge plasma at a strong 2p 5 3p-2p 5 3s transition of Ne-like Ar are experimentally investigated. To clarify the lasing mechanism, the results are compared with those obtained by numerical calculation using a one-dimensional magneto-hydrodynamics (MHD) simulation code. The comparison indicates that the lasing occurs when a cylindrically imploding shock wave arrives at the axis of the capillary and it depends not only on the electron density and temperature but also strongly on the effects of time-varying refraction and the opacity of the pinching plasma.

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“…In Equation (15), +0.4 stands for T e < 45 eV and −0.4 stands for T e 45 eV. The former work [41] had scaled the ionization time of Ne-like Ar +8 , which does not have electron temperature dependency.…”

Section: 6 7-9 10mentioning

confidence: 99%

Optimum Pump Pulse Duration for X-Ray Ar-Plasma Lasing

Masoudnia

Bleiner

2015

Photonics

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In plasma-driven X-ray lasers, it is critical to optimize the duration and time delay between pump pulses. In this study, we have done parametric simulations in order to systematically investigate the optimum time configuration of pump pulses. Here, we are mainly interested in soft X-ray lasers created using a Ar target irradiated with laser pulses, which operate at a wavelength λ = 46.9 nm in the 2p 5 3p 1 (J = 0) → 2p 5 3s 1 (J = 1) laser transition. It is shown that the optimum time scale required to achieve Ne-like ions, as well as the time required to generate a population inversion depend on the combined effect of the electron temperature and electron density. The electron density and temperature are respectively a factor of ≈2.1-and ≈5-times higher in the case of a short pulse of 0.1 ps in comparison to a long pulse of 1,000 ps (at a constant fluence). The most effective lasing happens with short pulses with a pulse duration comparable to the total relaxation time from the upper level, namely ∆τ p ≤ 35 ps. Power laws to predict the optimum laser intensity to achieve Ne-like Ar +8 are obtained.

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Effect of nonequilibrium ionization process on gain of neon-like argon x-ray laser

Cited by 8 publications

References 27 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

Effects of Plasma Dynamics on Lasing in Fast Capillary Discharge

Optimum Pump Pulse Duration for X-Ray Ar-Plasma Lasing

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