Robust estimate of dynamo thresholds in the von K\'arm\'an sodium experiment using the Extreme Value Theory
Abstract
We apply a new threshold detection method based on the extreme value theory to the von K\'arm\'an sodium (VKS) experiment data. The VKS experiment is a successful attempt to get a dynamo magnetic field in a laboratory liquid-metal experiment. We first show that the dynamo threshold is associated to a change of the probability density function of the extreme values of the magnetic field. This method does not require the measurement of response functions from applied external perturbations, and thus provides a simple threshold estimate. We apply our method to different configurations in the VKS experiment showing that it yields a robust indication of the dynamo threshold as well as evidence of hysteretic behaviors. Moreover, for the experimental configurations in which a dynamo transition is not observed, the method provides a way to extrapolate an interval of possible threshold values.
Keywords
Cite
@article{arxiv.1402.4275,
title = {Robust estimate of dynamo thresholds in the von K\'arm\'an sodium experiment using the Extreme Value Theory},
author = {Davide Faranda and Mickael Bourgoin and Sophie Miralles and Philippe Odier and Jean-Francois Pinton and Nicolas Plihon and François Daviaud and Bérengère Dubrulle},
journal= {arXiv preprint arXiv:1402.4275},
year = {2015}
}
Comments
10 pages, 7 figures