Signal Processing in Plasma Simulations

This project investigates the rotation frequency of plasma spokes in 2D simulations using advanced signal processing techniques.

MUSIC Method

The Multiple Signal Classification (MUSIC) algorithm was applied to achieve high-resolution frequency estimation. By modeling the plasma signal as a sum of coherent modes and separating them from noise through eigen-decomposition of the covariance matrix, the method revealed a dominant mode corresponding to the spoke frequency (~43.2 kHz).

MUSIC provides superior resolution compared to traditional FFT, allowing clear identification of low-amplitude modes and harmonics associated with azimuthal plasma structures.

CSD Method

The Cross Spectral Density (CSD) method was used to study coherence between two ion density probes placed at opposite locations. By examining amplitude and phase of S₁₂(f), shared oscillations between the probes were identified, confirming dominant rotation frequencies near 39–44 kHz.

CSD analysis complements the MUSIC method, validating the presence of coherent spoke modes and providing phase relationship insights between signals.