Formation of a population inversion of transitions in Ne-like ions in steady-state and transient plasmas

Afanas'ev, Yurii V; Shlyaptsev, V. N.

doi:10.1070/qe1989v019n12abeh009835

Cited by 88 publications

(28 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A recently demonstrated variation of the collisional electron excitation scheme takes advantage of the much larger population inversions that can be obtained under rapid transient excitation. [76][77][78] It was first recognized by Afanasiev and Shlyaptsev 146 that gain coefficients that are 1-2 orders of magnitude larger than those obtained for the same transition in the quasisteady state regime can be produced for a short period of time ͑typically subpicosecond to tens of picoseconds͒ by heating the plasma at a rate faster than the relaxation rate of the excited states. The larger gain coefficients are a consequence of several phenomena that, for a short period following rapid transient heating, contribute to generate a much higher population inversion.…”

Section: Transient Electron Collisional Excitationmentioning

confidence: 99%

“…Transient gains in excess of 100 cm Ϫ1 have been predicted theoretically. [146][147][148][149][150] The shortlived transient population inversions, which are pumped directly from the ground state by electron collisional excitation, last until collisions redistribute the populations among levels. Following this short transient period of high population inversion the gain decreases until the laser level populations finally reach the quasisteady state value.…”

Section: Transient Electron Collisional Excitationmentioning

confidence: 99%

See 1 more Smart Citation

Table-top Soft X-Ray Lasers

Rocca

2016

Conference on Lasers and Electro-Optics

View full text Add to dashboard Cite

This article reviews the progress in the development of practical table-top sources of soft x-ray laser radiation. The field is rapidly approaching the stage at which soft x-ray lasers sufficiently compact to fit onto a normal optical table will be routinely utilized in science and technology. This is the result of recent advances in the amplification of soft x-ray radiation in both compact laser-pumped and discharge-pumped devices. The use of excitation mechanisms that take full advantage of new ultrafast high power optical laser drivers and multiple pulse excitation schemes has resulted in the demonstration of saturated soft x-ray amplification at wavelengths as short as 14 nm using several Joule of laser-pump energy. Moreover, several schemes have demonstrated significant gain with only a fraction of a Joule of laser-pump energy. In addition, the demonstration of saturated table-top soft x-ray lasers pumped by very compact capillary discharges has shattered the notion that discharge-created plasmas are insufficiently uniform to allow for soft x-ray amplification, opening a route for the development of efficient, high average power soft x-ray lasers. Recently, a table-top capillary discharge laser operating at 46.9 nm has produced millijoule-level laser pulses at a repetition rate of several Hz, with a corresponding spatially coherent average power per unit bandwidth comparable to that of a beam line at a third generation synchrotron facility. This review summarizes fundamental and technical aspects of table-top soft x-ray lasers based on the generation of population inversions in plasmas, and discusses the present status of development of specific laser systems.

show abstract

Section: Transient Electron Collisional Excitationmentioning

confidence: 99%

Section: Transient Electron Collisional Excitationmentioning

confidence: 99%

Table-top Soft X-Ray Lasers

Rocca

2016

Conference on Lasers and Electro-Optics

View full text Add to dashboard Cite

show abstract

“…The latter is of concern in the longitudinal pumping geometry where all of the laser energy required for the full plasma column has to be propagated through the initial parts of the plasma. The RADEX simulation code [17] predicts that the absorption in the gain region can be increased from 5 -8% for transverse pumping to as high as 50 -70% for the GRIP geometry [9,10]. To illustrate the increased absorption, Fig.…”

Section: Grazing Incidence Pumping Geometrymentioning

confidence: 99%

Grazing incidence pumping for high efficiency x-ray lasers

2005

View full text Add to dashboard Cite

Over the last decade, most laser-driven collisional excitation x-ray lasers have relied on the absorption of the pump energy incident at normal incidence to a pre-formed plasma. The main advantage is that the inversion can be created at various plasma regions in space and time where the amplification and ray propagation processes are best served. The main disadvantage is that different plasma regions regardless of the contribution to the inversion have to be pumped simultaneously in order to make the laser work. This leads to a loss of efficiency. The new scheme of grazing incidence pumping (GRIP) addresses this issue. In essence, a chosen electron density region of a pre-formed plasma column, produced by a longer pulse at normal incidence onto a slab target, is selectively pumped by focusing a short pulse of 100 fs -10 ps duration laser at a determined grazing incidence angle to the target surface. The exact angle is dependent on the pump wavelength and relates to refraction of the drive beam in the plasma. The controlled use of refraction of the pumping laser in the plasma results in several benefits: The pump laser path length is longer and there is an increase in the laser absorption in the gain region for creating a collisional Ni-like ion x-ray laser. There is also an inherent traveling wave, close to c, that increases the overall pumping efficiency. This can lead to a 3 -30 times reduction in the pump energy for mid-Z, sub-20 nm lasers. We report several examples of this new x-ray laser on two different laser systems. The first demonstrates a 10 Hz x-ray laser operating at 18.9 nm pumped with a total of 150 mJ of 800 nm wavelength from a Ti:Sapphire laser. The second case is shown where the COMET laser is used both at 527 nm and 1054 nm wavelength to pump higher Z materials with the goal of extending the wavelength regime of tabletop x-ray lasers below 10 nm.

show abstract

“…2 The transient collisional excitation scheme as described by Afanasiev and Shlyaptsev has been proposed to achieve tabletop operation for laser-driven schemes. 3 This utilizes two laser pulses where a long nanosecond pulse at 10 12 W cm -2 generates the plasma and creates the required closed shell Ne-like or Ni-like ionization conditions. After a delay to allow for plasma cooling and expansion which is desirable for both optimum pumping and ray propagation along the plasma column, a second much shorter 1 ps laser pulse at 10 15 W cm -2 rapidly generates a transient population inversion.…”

Section: Introductionmentioning

confidence: 99%

Tabletop transient collisional excitation x-ray lasers

Dunn

Osterheld

et al. 1999

SPIE Proceedings

View full text Add to dashboard Cite

Recent transient collisional excitation x-ray laser experiments are reported using the COMET tabletop laser driver at the Lawrence Livermore National Laboratory (LLNL). Ne-like and Ni-like ion x-ray laser schemes have been investigated with a combination of long 600 ps and short ~1 ps high power laser pulses with 5 -10 J total energy. We show small signal gain saturation for x-ray lasers when a reflection echelon traveling wave geometry is utilized. A gain length product of 18 has been achieved for the Ni-like Pd 4d→4p J=0-1 line at 147 Å, with an estimated output of ~10µJ. Strong lasing on the 119 Å Ni-like Sn line has also been observed. To our knowledge this is the first time gain saturation has been achieved on a tabletop laser driven scheme and is the shortest wavelength tabletop x-ray laser demonstrated to date. In addition, we present preliminary results of the characterization of the line focus uniformity for a Ne-like ion scheme using L-shell spectroscopy.

show abstract

Formation of a population inversion of transitions in Ne-like ions in steady-state and transient plasmas

Cited by 88 publications

References 1 publication

Table-top Soft X-Ray Lasers

Table-top Soft X-Ray Lasers

Grazing incidence pumping for high efficiency x-ray lasers

Tabletop transient collisional excitation x-ray lasers

Contact Info

Product

Resources

About