Identifying nonlinear wave interactions in plasmas using two-point measurements: A case study of Short Large Amplitude magnetic Structures (SLAMS)

Two fundamental quantities for characterizing nonlinear wave phenomena in p lasmas are the spectral energy transfer associated with the energy redistri bution between Fourier modes, and the linear growth rate. It is shown how t hese quantities can be estimated simultaneously from dual-spacecraft data u sing Volterra series models. We consider magnetic field data gathered upstr eam the Earth's quasiparallel bow shock, in which Short Large Amplitude Mag netic Structures (SLAMS) supposedly play a leading role. The analysis attes ts the dynamic evolution of the SLAMS and reveals an energy cascade toward high-frequency waves. These results put constraints on possible mechanisms for the shock front formation.