Figure 3
(a) Dynamic spectrum of the magnetic field in the spin axis direction. The black line indicates the helium cyclotron frequency. The white dashed line shows the estimated frequency sweep rate. (b, c, d) Magnetic field wave amplitude, \({W}_{Eint}\), and \({W}_{Bint}\) calculated with the electromagnetic field bandpass filtered between 0.45 and 0.75 Hz (shown by dotted line), respectively. Black curves show the contour with the values = − 0.1. (e–g) Magnetic field wave amplitude, \({W}_{Eint}\), and \({W}_{Bint}\) calculated with the electromagnetic field bandpass filtered between 0.75 and 1.0 Hz, respectively. Black curves show the contour with the values \({W}_{Eint}=-0.1\), and \({W}_{Bint}=0.1\). The WPIA results, \({W}_{Eint}\), and \({W}_{Bint}\), have been calculated with protons of pitch angle between 125° and 145° (Created by using IDL 8.8 https://www.l3harrisgeospatial.com/Software-Technology/IDL).
