Stochastic analysis of subcritical amplification of magnetic energy in a turbulent dynamo

Sergei Fedotov, Irina Bashkirtseva and Lev Ryashko

Physica A: Statistical Mechanics and its Applications, 2004, vol. 342, issue 3, 491-506

Abstract: We present and analyze a simplified stochastic αΩ-dynamo model which is designed to assess the influence of additive and multiplicative noises, non-normality of dynamo equation, and nonlinearity of the α-effect and turbulent diffusivity, on the generation of a large-scale magnetic field in the subcritical case. Our model incorporates random fluctuations in the α-parameter and additive noise arising from the small-scale fluctuations of magnetic and turbulent velocity fields. We show that the noise effects along with non-normality can lead to the stochastic amplification of the magnetic field even in the subcritical case. The criteria for the stochastic instability during the early kinematic stage are established and the critical value for the intensity of multiplicative noise due to α-fluctuations is found. We obtain numerical solutions of nonlinear stochastic differential equations and find the series of phase transitions induced by random fluctuations in the α-parameter.

Keywords: Magnetic field; Non-normality; Stochastic amplification (search for similar items in EconPapers)
Date: 2004
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Citations: View citations in EconPapers (3)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:phsmap:v:342:y:2004:i:3:p:491-506

DOI: 10.1016/j.physa.2004.05.084

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