Ion contribution to the prominent Ne I, Ar I and Kr I spectral line broadening

Milosavljević, Vladimir; Djeniže, S.

doi:10.1051/0004-6361:20021654

Cited by 13 publications

(40 citation statements)

References 29 publications

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“…The spectrograph exit slit (10 μm) with calibrated photomultiplier was micrometrically traversed along the spectral plane in small wavelength steps (0.0073 nm). More details of experimental set‐up, recording technique, plasma reproducibility, deconvolution procedure and plasma diagnostics can be found in Milosavljević et al (2000), Milosavljević et al (2003), Milosavljević & Djeniže (2003) and Djeniže et al (2003). In the works of Milosavljević et al (2007) and Milosavljević, Popović & Ellingboe (2009), comprehensive electrical investigations of plasma homogeneity are presented.…”

Section: Methodsmentioning

confidence: 99%

Stark shifts and transition probabilities within the Kr I spectrum

Milosavljević¹,

Simić²,

Daniels³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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On the basis of 28 experimentally determined prominent neutral krypton (Kr I) line shapes (in the 5s-5p and 5s-6p transitions), we have obtained electron (d e ) and ion (d i ) contributions to the total Stark shifts (d t ). Stark shifts are also calculated using the semiclassical perturbation formalism (SCPF) for electrons, protons and helium ions as perturbers up to 50 000 K electron temperatures. Transition probabilities of spontaneous emission (Einstein's A k,i values) have been obtained using the relative line-intensity ratio method.The separate electron (d e ) and ion (d i ) contributions to the total Stark shifts are presented, as well as the ion-broadening parameters, which describe the influence of the ion-dynamical effect on the shift of the line shape, for neutral krypton spectral lines. We made a comparison of our measured and calculated d e data and compared both of these with other available experimental and theoretical d e values.

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Section: Methodsmentioning

confidence: 99%

Stark shifts and transition probabilities within the Kr I spectrum

Milosavljević¹,

Simić²,

Daniels³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…With A determined as a function of P a and the well-known relationship of A for this specific Ar emission line to an absolute N e (ref. 28), we can now derive N e from a single sonoluminescing bubble as a function of P a . Summarized in Table 1 are the determined conditions of the SBSL plasma (that is, temperature, plasma electron density and degree of ionization), as well as the properties of the emission lines and the antisymmetric deviation functions, all as a function of P a .…”

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Inertially confined plasma in an imploding bubble

2010

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Models of spherical supersonic bubble implosion in cavitating liquids predict that it could generate temperatures and densities sufficient to drive thermonuclear fusion 1,2 . Convincing evidence for fusion is yet to be shown, but the transient conditions generated by acoustic cavitation are certainly extreme 3-5 . There is, however, a remarkable lack of observable data on the conditions created during bubble collapse. Only recently has strong evidence of plasma formation been obtained 6 . Here we determine the plasma electron density, ion-broadening parameter and degree of ionization during single-bubble sonoluminescence as a function of acoustic driving pressure. We find that the electron density can be controlled over four orders of magnitude and exceed 10 21 cm −3 -comparable to the densities produced in laser-driven fusion experiments 7 -with effective plasma temperatures ranging from 7,000 to more than 16,000 K. At the highest acoustic driving force, we find that neutral Ar emission lines no longer provide an accurate measure of the conditions in the plasma. By accounting for the temporal profile of the sonoluminescence pulse and the potential optical opacity of the plasma, our results suggest that the ultimate conditions generated inside a collapsing bubble may far exceed those determined from emission from the transparent outer region of the light-emitting volume.A bubble acoustically driven into nonlinear radial oscillation can focus the diffuse energy of the sound field by many orders of magnitude 8 . The energy focusing is such that broadband light emission is observed (sonoluminescence) 4 and molecular bonds are broken (sonochemistry) 9 . Measurement of the bubble dynamics of a single sonoluminescing bubble (single-bubble sonoluminescence (SBSL)) has shown the implosion velocity to be greater than the speed of sound with enormous acceleration near maximum collapse 10 . The bubble dynamics and the properties of the emitted light suggest the generation of extreme intracavity conditions. Indeed, recent molecular dynamics simulations predict temperatures approaching 10 8 K but lasting for only a few hundred femtoseconds 2 . The extreme conditions generated during SBSL arise from quasi-adiabatic compression of the bubble contents. One measure of the intensity of bubble implosion is the ratio of maximum to minimum bubble volume (that is, compression ratio). The value of the compression ratio, and hence the bubble kinetic energy, increases with increasing acoustic pressure (P a ; ref. 11). Thus, at high P a there is more energy available to be transferred to the bubble contents, which should ultimately produce more extreme intracavity conditions.Recently, Taleyarkhan and co-workers claimed to observe neutrons during acoustic cavitation in deuterated acetone 12,13 resulting from intracavity fusion reactions (that is, 'sonofusion'). These reports were met with immediate skepticism, and serious issues with the validity of the claims arose 14,15 . Indeed, subsequent studies in several independent laboratories ha...

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“…To estimate n e , the asymmetry of the SBSL Ar 763.51 nm line was used to determine the static ion broadening parameter (A), following a technique described by Jones et al [18]. Since A scales as n 1=4 e [17], we can compare the A determined here to values of A obtained at known n e for the Ar 763.51 nm line [23]. From this, n e 3:8 10 17 cm ÿ3 , as determined for SBSL with an applied P a of 3.6 bar; this value agrees well with that estimated from Ref.…”

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Measurement of Pressure and Density Inside a Single Sonoluminescing Bubble

et al. 2006

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The average pressure inside a sonoluminescing bubble in sulfuric acid has been determined by two independent techniques: (1) plasma diagnostics applied to Ar atom emission lines, and (2) light scattering measurements of bubble radius vs time. For dimly luminescing bubbles, both methods yield intracavity pressures approximately 1500 bar. Upon stronger acoustic driving of the bubble, the sonoluminescence intensity increases 10,000-fold, spectral lines are no longer resolved, and radius vs time measurements yield internal pressures > 3700 bar. Implications for a hot inner core are discussed.

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Ion contribution to the prominent Ne I, Ar I and Kr I spectral line broadening

Cited by 13 publications

References 29 publications

Stark shifts and transition probabilities within the Kr I spectrum

Stark shifts and transition probabilities within the Kr I spectrum

Inertially confined plasma in an imploding bubble

Measurement of Pressure and Density Inside a Single Sonoluminescing Bubble

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