Evidence of turbulence in laser-induced plasmas

Roberson, Stephen D.; Akpovo, Charlemagne; Mezonlin, Ephrem; Johnson, J. A.

doi:10.1063/1.2841770

Cited by 3 publications

(7 citation statements)

References 17 publications

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“…We choose air as the target medium; first of all, because the general features of laser induced turbulent plasmas in air are well understood [4]. The Tektronix digitizing oscilloscope that is used to capture the signal of the plasma sent through the PMT has a sampling speed of 50 GS s −1 .…”

Section: Methodsmentioning

confidence: 99%

“…The turbulent energy provides a systematic way to determine the total strength of the fluctuations in the signal [4]. The turbulent energy provides a systematic way to determine the total strength of the fluctuations in the signal [4].…”

Section: Analytical Techniquesmentioning

confidence: 99%

“…Turbulent effects have been observed in plasmas produced by arc-driven shock waves, microwave generated plasmas, moving and stationary plasmas, and in laser-induced plasmas [1][2][3][4]. However, no research has gone into understanding the turbulent environment of a laser-induced plasma produced directly in the path of a high irradiance continuous wave (cw) laser.…”

Section: Introductionmentioning

confidence: 99%

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Turbulence changes in laser enhanced laser induced plasmas

Wiggins¹,

Raynor²,

Johnson³

2010

J. Plasma Phys.

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A neodymium-doped yttrium aluminum garnet laser of wavelength 0.532 µm with the maximum energy of 900 mJ creates plasmas at a focal point in air in the path of a 1 kW continuous wave fiber laser of wavelength 1.08 µm. We find that there is an unexpected influence on a standard set of turbulent parameters in these laser-induced plasmas. Specifically, the continuous wave laser increased the complexity in the turbulent fluctuations. The continuous wave laser reduces the characteristic fluctuation frequencies in the neutral lines. Furthermore, the continuous wave laser enhances turbulence energies in ions while it diminishes turbulence energies in neutrals.

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Section: Methodsmentioning

confidence: 99%

Section: Analytical Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Turbulence changes in laser enhanced laser induced plasmas

Wiggins¹,

Raynor²,

Johnson³

2010

J. Plasma Phys.

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“…11) to 4.0 GHz. 19 Through the measurement of the turbulent parameters, turbulent profiles can be measured, which correlate to different phases of plasma phenomena.…”

Section: Introductionmentioning

confidence: 99%

“…These parameters have been measured in plasmas created by both arc-driven [12][13][14][15][16] and diaphragm 17 shock tubes, glow discharge tubes, 11,18 microwaves, 21,22 Nd:YAG, 19 and CW 20 lasers. These turbulent characteristics were measured on time scales from micro to nanosecond, at data rates between 250.0 kHz (Ref.…”

Section: Introductionmentioning

confidence: 99%

Mass dependency of turbulent parameters in stationary glow discharge plasmas

et al. 2013

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A direct current glow discharge tube is used to determine how mass changes the effects of certain turbulence characteristics in a weakly ionized gas. Helium, neon, argon, and krypton plasmas were created, and an axial magnetic field, varied from 0.0 to 550.0 Gauss, was used to enhance mass dependent properties of turbulence. From the power spectra of light emission variations associated with velocity fluctuations, determination of mass dependency on turbulent characteristic unstable modes, energy associated with turbulence, and the rate at which energy is transferred from scale to scale are measured. The magnetic field strength is found to be too weak to overcome particle diffusion to the walls to affect the turbulence in all four types of plasmas, though mass dependency is still detected. Though the total energy and the rate at which the energy moves between scales are mass invariant, the amplitude of the instability modes that characterize each plasma are dependent on mass. V C 2013 AIP Publishing LLC. [http://dx.

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The time evolution of turbulent parameters in reversed-field pinch plasmas

Titus

Alexander

Johnson

2013

Journal of Applied Physics

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Turbulence is abundant in fully ionized fusion plasmas, with unique turbulent characteristics in different phases of the discharge. Using Fourier and chaos-based techniques, a set of parameters have been developed to profile the time evolution of turbulence in high temperature, fusion plasmas, specifically in self-organized, reversed-field pinch plasma in the Madison Symmetric Torus. With constant density and plasma current, the turbulence profile is measured during ramp-up, magnetic reconnection, and increased confinement phases. During magnetic reconnection, a scan of plasma current is performed with a constant density. Analysis revealed that the energy associated with turbulence (turbulent energy) is found to increase when changes in magnetic energy occur and is correlated to edge ion temperatures. As the turbulent energy increases with increasing current, the rate at which this energy flow between scales (spectral index) and anti-persistence of the fluctuations increases (Hurst exponent). These turbulent parameters are then compared to the ramp-up phase and increased confinement regime.

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Evidence of turbulence in laser-induced plasmas

Cited by 3 publications

References 17 publications

Turbulence changes in laser enhanced laser induced plasmas

Turbulence changes in laser enhanced laser induced plasmas

Mass dependency of turbulent parameters in stationary glow discharge plasmas

The time evolution of turbulent parameters in reversed-field pinch plasmas

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