An Introduction to the Atomic and Radiation Physics of Plasmas

Tallents, G. J.

doi:10.1017/9781108303538

Cited by 23 publications

(29 citation statements)

References 103 publications

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“…Theoretical treatments predict a substantial (several orders of magnitude) reduction of the rates of collisional ionization and recombination with increasing degeneracy, yet experimental confirmation is so far lacking [34,40,41]. To test these predictions, the rate of collisional ionization or recombination must be measured in a plasma of known degeneracy.…”

Section: Experimental Approachmentioning

confidence: 99%

“…The CF values are calculated following theoretical frameworks presented elsewhere and are plotted as a function of degeneracy, , in Fig. 2 (see caption for details) [34,40,41]. The two processes dominating the number of Lshell vacancies in time are collisional ionization (CI) and its inverse process, three-body recombination (3BR), which are shown as dashed and solid curves in Fig.…”

Section: Plasma Conditions and Corrections To The Ratesmentioning

confidence: 99%

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Impact of free electron degeneracy on collisional rates in plasmas

Williams

Chung

Künzel

et al. 2019

Phys. Rev. Research

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Degenerate plasmas, in which quantum effects dictate the behavior of free electrons, are ubiquitous on earth and throughout space. Transitions between bound and free electron states determine basic plasma properties, yet the effects of degeneracy on these transitions have only been theorized. Here, we use an x-ray free electron laser to create and characterize a degenerate plasma. We observe a core electron fluorescence spectrum that cannot be reproduced by models that ignore free electron degeneracy. We show that degeneracy acts to restrict the available electron energy states, thereby slowing the rate of transitions to and from the continuum. We couple degeneracy and bound electron dynamics in an existing collisional-radiative code, which agrees well with observations. The impact of the shape of the cross section, and hence the magnitude of the correction due to degeneracy, is also discussed. This study shows that degeneracy in plasmas can significantly influence experimental observables such as the emission spectra, and that these effects can be included parametrically in well-established atomic physics codes. This work narrows the gap in understanding between the condensed-matter and plasma phases, which coexist in myriad scenarios.

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Section: Experimental Approachmentioning

confidence: 99%

Section: Plasma Conditions and Corrections To The Ratesmentioning

confidence: 99%

Impact of free electron degeneracy on collisional rates in plasmas

Williams

Chung

Künzel

et al. 2019

Phys. Rev. Research

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“…The absorption coefficient for inverse bremsstrahlung, or free-free, absorption can be found by calculating black body emission due to bremsstrahlung and then using detailed balance to find the absorption coefficient. This is a treatment used by Hutchinson 5 and Tallents 6 . The free-free absorption coefficient, K f f , can then be found as…”

Section: Euv Absorption Mechanismsmentioning

confidence: 99%

Modelling extreme ultraviolet ablation interactions

Lolley

Wilson

Tallents

2019

Optics Damage and Materials Processing by EUV/X-ray Radiation VII

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Compact extreme ultraviolet (EUV) laser sources can be used for laboratory-scale ablation experiments at intensities of 1 × 10 11 W cm −2 and higher. The depths of ablation achieved using focused laser output at 46.9 nm to irradiate solid targets of aluminium, gold, and copper have been modeled. Two simple models are considered; an adaptation of an ultra-short pulse model, and an ablation velocity model. We show that the attenuation length of the material plays an important role in the physics of the ablation. A more detailed one-dimensional model including absorption by inverse bremsstrahlung absorption and photo-ionization, corrected to include electron degeneracy effects, is used to evaluate the opacity of the ablation plasma and subsequent ablation depths.

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“…By optimizing the angle of incidence of the optical laser beams creating the plasma medium, saturated tabletop lasers over the wavelength range 16.5 -13.9 nm were produced with only 1 J per pulse of the optical laser [3]. The work on soft x-ray lasers pumped by optical lasers has created useful short wavelength lasers for applications and led to a greater understanding of laser-plasmas and the atomic physics of hot plasmas which has relevance to much wider fields of study [4].…”

Section: Introductionmentioning

confidence: 99%

Extreme ultraviolet laser ablation of solid targets

Tallents

Wilson

Lolley

et al. 2019

X-Ray Lasers and Coherent X-Ray Sources: Development and Applications XIII

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A capillary laser with output in the extreme ultraviolet at wavelength 46.9 nm is used to ablate solid targets of parylene-N (CH), PMMA, aluminum and gold. We summarize results obtained using different focusing optics: a Fresnel zone plate, an off-axis spherical multi-layer mirror and on-axis multi-layer and gold mirrors. The Fresnel zone plate has a small aperture and focuses a small fraction of the laser energy to a small diameter (< 1 µm) with peak intensities 6 x 10 9 Wcm-2. The off-axis spherical multi-layer mirror allows for a measurement of the transmission of the laser through thin targets, but the off-axis geometry produced an aberrated focus. The on-axis multi-layer mirror allows focusing to intensities of approximately 5 x 10 10 Wcm-2 with a cylindrically symmetric focus.

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An Introduction to the Atomic and Radiation Physics of Plasmas

Cited by 23 publications

References 103 publications

Impact of free electron degeneracy on collisional rates in plasmas

Impact of free electron degeneracy on collisional rates in plasmas

Modelling extreme ultraviolet ablation interactions

Extreme ultraviolet laser ablation of solid targets

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