Effect of Background Fluctuations on Nonlinear Evolution of Kinetic Alfvén Wave and Turbulent Spectrum

English Abstract:

Effect of Background Fluctuations on Nonlinear Evolution of Kinetic Alfvén Wave and Turbulent Spectrum

Anju Kumari¹ and R. P. Sharma¹

¹Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi-110016, India

ABSTRACT

We have studied the effect of background density fluctuations on the formation of localized large amplitude structures and turbulent spectrum of kinetic Alfvén wave (KAW) applicable to magnetopause. Numerical simulation has been performed to study these structures. Localization becomes more intense with the growth of numerous structures at later times. From the results, we found that background fluctuations affect the localization process of KAW. Simulation results reveal that power spectrum deviates from Kolmogorov scaling at the transverse size of KAW, equal to ion gyroradius. Steepening of power spectrum at shorter wavelengths may be accountable for heating and acceleration of the plasma particles. Thus the presented coupling suggests a mechanism of energy transfer from larger length-scales to smaller length-scales. The relevance of present investigation with observations collected from the THEMIS spacecraft in magnetopause is also discussed [Chaston et al., 2008].

Reference

[1] Chaston, C., J. Bonnell, J. P. McFadden, C. W. Carlson, C. Cully, O. Le Contel A. Roux, H. U. Auster, K. H. Glassmeier, V. Angelopoulos, C. T. Russell (2008), Turbulent heating and cross-field transport near the magnetopause from THEMIS, Geophys. Res. Lett., 35, L17S08.