Observations of turbulence within reconnection jet in the presence of guide field

Abstract

We present the first comprehensive observations of turbulence properties within high speed reconnection jet in the plasma sheet with moderate guide field. The power spectral density index is about −1.73 in the inertial range, and follows the value of −2.86 in the ion dissipation range. The turbulence is strongly anisotropic in the wave‐vector space with the major power having its wave‐vector highly oblique to the ambient magnetic field, suggesting that the turbulence is quasi‐2D. The measured “dispersion relations” obtained using the k‐filtering technique are compared with theory and are found to be consistent with the Alfvén‐Whistler mode. In addition, both Probability Distribution Functions and flatness results show that the turbulence in the reconnection jet is intermittent (multifractal) at scales less than the proton gyroradius/inertial lengths. The estimated electric field provided by anomalous resistivity caused by turbulence is about 3 mV/m, which is close to the typical reconnection electric field in the magnetotail.