Analysis of cancellation exponents in two-dimensional Vlasov turbulence

Vita, Gaetano De; Sorriso‐Valvo, L.; Valentini, F.; Servidio, S.; Primavera, Leonardo; Carbone, V.; Veltri, P.

doi:10.1063/1.4891339

Cited by 6 publications

(6 citation statements)

References 33 publications

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“…A similar behaviour was observed in the small-scale evolution of two-dimensional Vlasov–Maxwell turbulence (De Vita et al. 2014), where a 3-D-extrapolated dimension was measured. In the SH run, the presence of velocity shears accelerates the nonlinear transfer, favouring an early appearance of small-scale structures, which eventually reach a steady geometry around the same time as for the AP run.…”

Section: Resultssupporting

confidence: 81%

“…Cancellation analysis has recently been used to track the time evolution of turbulence in a two-dimensional numerical simulation of the hybrid Vlasov–Maxwell equations (De Vita et al. 2014), showing its ability to highlight the transition to turbulence. Moreover, could accurately describe the formation and the geometrical characteristics of the main structures generated by the nonlinear interaction, independent of the type of turbulence.…”

Section: Resultsmentioning

confidence: 99%

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Three-dimensional simulations of sheared current sheets: transition to turbulence?

et al. 2017

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Systems of multiple current sheets arise in various situations in natural plasmas, such as at the heliospheric current sheet in the solar wind and in the outer heliosphere in the heliosheath. Previous three-dimensional simulations have shown that such systems can develop turbulent-like fluctuations resulting from a forward and inverse cascade in wave vector space. We present a study of the transition to turbulence of such multiple current sheet systems, including the effects of adding a magnetic guide field and velocity shears across the current sheets. Three-dimensional hybrid simulations are performed of systems with eight narrow current sheets in a triply periodic geometry. We carry out a number of different analyses of the evolution of the fluctuations as the initially highly ordered state relaxes to one which resembles turbulence. Despite the evidence of a forward and inverse cascade in the fluctuation power spectra, we find that none of the simulated cases have evidence of intermittency after the initial period of fast reconnection associated with the ion tearing instability at the current sheets. Cancellation analysis confirms that the simulations have not evolved to a state which can be identified as fully developed turbulence. The addition of velocity shears across the current sheets slows the evolution in the properties of the fluctuations, but by the end of the simulation they are broadly similar. However, if the simulation is constrained to be two-dimensional, differences are found, indicating that fully three-dimensional simulations are important when studying the evolution of an ordered equilibrium towards a turbulent-like state.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Three-dimensional simulations of sheared current sheets: transition to turbulence?

et al. 2017

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“…In these conditions, the cancellation functions show variable sign-singularity, so that the cancellation exponents are highly fluctuating. A similar behaviour was recently observed in direct numerical simulations for the study of the transition to turbulence in kinetic dynamics of plasmas (De Vita et al 2014;Wan et al 2012), and is due to the presence of not yet fully developed structures.…”

Section: General Temporal Dynamical Properties: Turbulent Dissipationsupporting

confidence: 84%

“…Signed measure has been successfully used to describe the cancellation properties of magnetic dynamo (Ott et al 1992), as well as the characteristics of current structures in turbulent magnetohydrodynamic (MHD) (Sorriso-Valvo et al 2002;Graham et al 2005), Hall-MHD (Martin et al 2013), and kinetic (De Vita et al 2014;Wan et al 2012) numerical simulations. Applications to measurements of magnetic vectors in solar active regions have confirmed cancellation analysis as an interesting tool to detect changes in the scaling properties of the fields fluctuations, and of the fractal dimension of the associated gradients Abramenko et al 1998;Sorriso-Valvo et al 2004).…”

Section: Signed Measure and Cancellation Analysismentioning

confidence: 99%

Sign Singularity and Flares in Solar Active Region Noaa 11158

Sorriso‐Valvo

Vita

Kazachenko

et al. 2015

ApJ

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Solar Active Region NOAA 11158 has hosted a number of strong flares, including one X2.2 event. The current density and current helicity complexity properties are studied through cancellation analysis of their sign-singular measure, which features power-law scaling. Spectral analysis is also performed, revelaing the presence of two separate scaling ranges with diffrent spectral index. The time evolution of parameters is discussed. Sudden changes of the cancellation exponents at the time of large flares, and the presence of correlation with EUV and X-ray flux, suggest that eruption of large flares can be linked to the small scale properties of the current structures.

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“…fractal dimension, filling factor...) of sign-defined (smooth) coherent structures, such as the ones emerging in intermittent, turbulent flows. A standard technique to estimate sign singularity is provided by the cancellation analysis, previously used to describe the scaling properties of MHD, Hall-MHD and Vlasov-Maxwell turbulence in numerical simulations [44,[62][63][64][65] and in the current helicity in solar photospheric active regions [66][67][68][69].…”

Section: B Sign Singularity and Cancellation Analysismentioning

confidence: 99%

Sign Singularity of the Local Energy Transfer in Space Plasma Turbulence

et al. 2019

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2In weakly collisional space plasmas, the turbulent cascade provides most of the energy that is dissipated at small scales by various kinetic processes. Understanding the characteristics of such dissipative mechanisms requires the accurate knowledge of the fluctuations that make energy available for conversion at small scales, as different dissipation processes are triggered by fluctuations of a different nature. The scaling properties of different energy channels are estimated here using a proxy of the local energy transfer, based on the third-order moment scaling law for magnetohydrodynamic turbulence. In particular, the sign-singularity analysis was used to explore the scaling properties of the alternating positive-negative energy fluxes, thus providing information on the structure and topology of such fluxes for each of the different type of fluctuations. The results show the highly complex geometrical nature of the flux, and that the local contributions associated with energy and cross-helicity nonlinear transfer have similar scaling properties. Consequently, the fractal properties of current and vorticity structures are similar to those of the Alfvénic fluctuations. PACS numbers: 94.05.-a, 94.05.Lk, 95.30.Qd

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Analysis of cancellation exponents in two-dimensional Vlasov turbulence

Cited by 6 publications

References 33 publications

Three-dimensional simulations of sheared current sheets: transition to turbulence?

Three-dimensional simulations of sheared current sheets: transition to turbulence?

Sign Singularity and Flares in Solar Active Region Noaa 11158

Sign Singularity of the Local Energy Transfer in Space Plasma Turbulence

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