Electron and field properties during the type III event. Panel a gives the electron velocity distribution function during an 80-second interval surrounding the 15-millisecond-long Langmuir wave. It describes the core, halo, and strahl distributions, which show that the average core electron density and thermal velocity were 181 cm⁻³ and 2887 km/s. Panel b gives the hodogram of the electric field during this event. The hodogram is in the X − Y plane, but because B_Z ≈ 0, it describes the relation between the electric field and the magnetic field direction, which is the green line. The electric field is generally parallel to the magnetic field, with significant deviations that are described in Figure 2d. The red curve in Figure 3b represents one period of the wave at the time of the data in Figure 6.