Eur. Phys. J. D (2015) 69: 8
https://doi.org/10.1140/epjd/e2014-50240-2

Regular Article

Bicoherence analysis of streamer dynamics induced by trapped ion modes^*

¹ LMFA, École Centrale de Lyon, Université de Lyon, 69134 Ecully, France
² CEA, IRFM, 13108 Saint-Paul-Lez-Durance, France
³ Institut Jean Lamour-UMR 7168, Université de la Lorraine, 54506 Nancy, France

^a e-mail: francesco.palermo@ec-lyon.fr

Received: 25 March 2014
Received in final form: 25 August 2014
Published online: 8 January 2015

Abstract

High order spectral analyses have recently attracted a great deal of attention in the context of experimental studies for magnetic fusion. Among these techniques, bicoherence analysis plays an important role as it allows distinguishing between spontaneously excited waves and waves that arise from a coupling between different modes linked to specific physical mechanisms. Here, we describe and apply bicoherence analysis to kinetic simulations performed with reduced “bounce-averaged gyrokinetic” code, in order to investigate the nonlinear dynamics of trapped ion modes. This analysis shows a nonlinear wave coupling process linked to the formation of convective cells, thus furthers our understanding of the nonlinear energy transfer between turbulence structures in tokamaks.