Fig. 1: MMS observations of an electromagnetic ion cyclotron wave event.
From: Anomalous resonance between low-energy particles and electromagnetic plasma waves
a Magnetic fields in the Geocentric Solar Eclipse coordinates, with the x, y, z components and total magnetic field strength indicated by the black, blue, red and green lines, respectively. b Wavelet power spectra of the \({\perp }_{1}-{\perp }_{2}\) components of B1. c Wave magnetic field. d Wave electric field. e 3-s averaged Poynting flux. In panels (c–e), the black, blue and red lines represent the ⊥1, ⊥2 and ∥ components in the field-aligned coordinates, respectively. f Wave phase speed. g–i Gyro-phase spectra of phase space density (PSD) for perpendicular-moving ions (pitch angles between 90°±11.25°) within the 53-, 441-, and 974-eV energy channels, respectively, with the phase of B1 indicated by the blue lines. j Energy spectrum of PSD in log scale for the ions with pitch angles between 90°±11.25° and phase angle between 150° and 180°. k, l Gyro-phase spectra of PSD for ions (pitch angles between 0°–50°) within the 974- and 1269-eV energy channels, respectively.
