&lt;title&gt;Recent x-ray laser experiments on the COMET facility&lt;/title&gt;

Dunn, James P.; Smith, R. F.; Nilsen, Joseph; Hunter, Jim R.; Barbee, Troy W.; Shlyaptsev, Vyacheslav N.; Chamatropulos, Jorge Filevich; Rocca, J. J.; Marconi, M. C.; Fiedorowicz, Henryk; Bartnik, A.

doi:10.1117/12.450575

Cited by 11 publications

(6 citation statements)

References 33 publications

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“…Using these interferometers, they observed the dynamics of high-density plasmas. Using a transient collisional excitation type nickel-like palladium soft x-ray laser at the wavelength of 14.7 nm, Dunn et al (2001) have demonstrated Mach-Zender type interferometer using gratings as beam splitters, which is shown schematically in figure 59. A line-focused laser produced cylindrical plasma was probed by a few ps x-ray laser pulse, resulting in good interferograms as shown in figure 60.…”

Section: Soft X-ray Laser Interferometersmentioning

confidence: 99%

Review of soft x-ray laser researches and developments

Daido¹

2002

Rep. Prog. Phys.

207

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In this paper, the author reviews the plasma-based x-ray lasers which we have already demonstrated saturated amplification whose wavelengths are between 50 and 6 nm.Section 1 describes the motivation of this review paper which includes basic ideas, developments and their applications of x-ray lasers. In section 2, the author describes the early x-ray laser researches on the recombination and the electron collisional excitation schemes including the hydrogen-like and lithium-like ion recombination schemes and the electron collisional excitation scheme. Section 3 describes the first demonstration of significant lasing at Livermore for the electron collisional excitation scheme of neon-like selenium ions at a wavelength of 20.6 and 20.9 nm and Princeton for the recombination scheme of hydrogenlike carbon ions at a wavelength of 18.2 nm. In section 4, the author describes the electron collisional excitation type soft x-ray lasers which are at present the most successful x-ray lasers. The subjects with which the author deals are saturated amplification neon-like soft x-ray lasers, improvement of neon-like soft x-ray laser performance using multi-layer mirrors, atomic physics issues of the neon-like soft x-ray lasers, gain guiding of the x-ray laser beam propagation, discharge-pumped compact repetitive neon-like ion soft x-ray lasers, the collisional excitation nickel-like ion soft x-ray lasers, high gain and saturated amplification nickel-like soft x-ray lasers at wavelengths as short as 7 nm, the short wavelength nickel-like x-ray lasers whose wavelengths are close to the longest wavelength edge the water window of 4.4 nm, transient collisional excitation scheme which is currently the most popular soft x-ray lasers pumped by short-pulse compact lasers with a laser energy of a few J to a few tens of J. In section 5, the author describes various plasma-based x-ray laser schemes other than the recombination and the collisional schemes, such as the optical field ionization schemes and inner-shell ionization schemes. Section 6 includes soft x-ray laser applications such as soft x-ray holography, soft x-ray interferometers, soft x-ray microscopy and other applications. In section 7, the author summarizes this review paper and he proposes a future direction for x-ray laser researches.

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Section: Soft X-ray Laser Interferometersmentioning

confidence: 99%

Review of soft x-ray laser researches and developments

Daido¹

2002

Rep. Prog. Phys.

207

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“…With increasing prepulse amplitude the modulations of the far-field showed a tendency to become weaker and more irregular. The angular frequency and the modulation depth are considerably lower compared to the interference fringes observed in the far-field beam patterns of [11,12].…”

mentioning

confidence: 69%

Simultaneous imaging of the near- and far-field intensity distributions of the Ni-like Sn X-ray laser

Staub

Braud

Balmer

et al. 2004

Applied Physics B: Lasers and Optics

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We report two-dimensional near-field imaging experiments of the 11.9-nm Sn X-ray laser that were performed with a set of novel Mo/Y multilayer mirrors having reflectivities of up to ∼ 40% at normal and at 45 • incidence. Second-moment analysis of the X-ray laser emission was used to determine values of the X-ray beam propagation factor M 2 for a range of irradiation parameters. The results reveal a reduction of M 2 with increasing prepulse intensity. The spatial size of the output is a factor of ∼ 2 smaller than previously measured for the 14.7-nm Pd X-ray laser, while the distance of the X-ray emission with respect to the target surface remains roughly the same.PACS 42.55.Vc IntroductionSince the first demonstration of substantial X-ray laser gain in neon-like selenium [1], the electron-collisional excitation scheme has proven to be the most successful method on the route towards high output power and saturated gain. Saturated operation of soft-X-ray lasers is important because it assures the maximum stimulated-emission power extraction from a given volume of excited plasma. Clear evidence of saturation has been reported in the last few years by a number of authors for the 4 d → 4p, J = 0-1 transition in nickel-like elements at wavelengths between 14.7 and 7.3 nm [2][3][4]. The efficiency with which saturation is achieved in the Ni-like lasers has recently been improved by exploiting the prepulse and multiple-pulse techniques [5][6][7] and, on the other hand, by reducing the pump pulse duration to the picosecond range, combined with traveling-wave irradiation [8]. Reports on the properties of these lasers have included measurements of the output energy, pulse duration, near-and far-field intensity distributions, and divergence [9]. The recent development of novel Mo/Y multilayer X-ray mirrors [10] has opened up a new wavelength range from 7 to 12 nm for imaging experiments of soft X-rays not accessible so far. In previous experiments, we have demonstrated saturated gain on the 4 d → 4p, J = 0-1 transition in Ni-like Pd, Ag, and Sn at 14.7, 13.9, and 11.9 nm, respectively, with a pump irradiation scheme utilizing a 0.5% prepulse that irradiated flat-slab targets 5-6 ns before the main pulse. Both the prepulse and the main pulse had a duration of 100 ps. In this work we report a series of simultaneous near-and far-field imaging experiments for the Sn 11.9-nm X-ray laser using four different prepulse schemes: a 0.5% prepulse at −6 ns, a 2.8% prepulse at −2 ns, a 8% prepulse at −1 ns, and a 16% prepulse at −0.8 ns. Experimental setupThe experiments were performed using the 1054-nm Nd : glass laser system at the Institute for Applied Physics (IAP) of the University of Berne. The laser, having a final amplifier of 90-mm diameter, is capable of delivering up to 40 J at a pulse duration of 100 ps (FWHM). The output beam is focused to give a line focus of 2.5-cm length and approximately 100-µm width using a combination of a 500-mm focal length aplanatic doublet and a −1700-mm focal length cylindrical lens. Targ...

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“…Total energy in the two beams is of order 3 -7 J to produce lasing where the peak-to-peak delay between the laser pulses is found to be optimal at 700 ps with the short pulse arriving after the long pulse. High photon flux/shot, high monochromaticity, and short pulse duration when combined with small source area and beam divergence properties of the 14.7 nm line [14] give ultra-high peak brightness ~ 10 25 ph. mm -2 mrad -2 s -1 (0.1% BW) -1 assuming a 2 ps pulse duration.…”

Section: Methodsmentioning

confidence: 99%

Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy

et al. 2005

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Time-resolved soft x-ray photoelectron spectroscopy is used to probe the non-steady-state evolution of the valence band electronic structure of laser heated ultra-thin (50 nm) metal foils and bulk semiconductors. Single-shot soft x-ray laser induced time-of-flight photoelectron spectroscopy with picosecond time resolution was used in combination with optical measurements of the disassembly dynamics that have shown the existence of a metastable liquid phase in fs-laser heated metal foils persisting 4-5 ps. This metastable phase is studied using a 527 nm wavelength 400 fs laser pulse containing 0.3 -2.5 mJ laser energy focused in a large 500 x 700 µm 2 spot to create heated conditions of 0.2 -1.8 x 10 12 W cm -2 intensity. The unique LLNL COMET compact tabletop soft x-ray laser source provided the necessary high photon flux, highly monoenergetic, picosecond pulse duration, and coherence for observing the evolution of changes in the valence band electronic structure of laser heated metals and semiconductors with picosecond time resolution. This work demonstrates the continuing development of a powerful new technique for probing reaction dynamics and changes of local order on surfaces on their fundamental timescales including phenomena such as non-thermal melting, chemical bond formation, intermediate reaction steps, and the existence of transient reaction products.

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<title>Recent x-ray laser experiments on the COMET facility</title>

Cited by 11 publications

References 33 publications

Review of soft x-ray laser researches and developments

Review of soft x-ray laser researches and developments

Simultaneous imaging of the near- and far-field intensity distributions of the Ni-like Sn X-ray laser

Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy

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