Difference of Intermittency between Electric Field and Magnetic Field Fluctuations from Ion Scale Down to Sub-electron Scale in the Magnetosheath Turbulence

Abstract

We use the measurements from the Magnetospheric MultiScale spacecraft to study the intermittency of the magnetic field ( B -field) and electric field ( E -field) fluctuations from ion scales (around 1 Hz in the spacecraft frame) to sub-electron scales (about 1000Hz) in the magnetosheath. For the first time, this study shows remarkable differences of intermittent properties between these two fields: (1) The multiorder structure functions of E -field trace fluctuations are more flattened as compared to those of B -field trace fluctuations. (2) The flatness of E -field fluctuations increases monotonically with decreasing scales and eventually exceeds 100 at 1000 Hz, whereas the flatness of B -field fluctuations does not rise so high (less than 100) and tends to fall off at frequencies larger than 1000 Hz. (3) It is revealed that ζ ( p ) monotonically and quasi-linearly increases with increasing p for B -field fluctuations even at sub-electron scales. However, ζ ( p ) for E -field is concave, turning over at around p  = 2 from increasing to decreasing trends. We quantitatively analyze and find that, with decreasing scales (defined as τ ), the variance of (defined as λ 2 ), where σ is the local standard deviation, increases much more slowly than the most probable (defined as μ ) decreases (i.e., ) for the B -field case, while the changing rate of the two quantities are of the same order for the E -field case. These results indicate the distinct intermittency nature between magnetic and electric fields and impose a constraint on theoretical turbulence models.