Radial Evolution of the Ion-Scale Cyclotron Waves from 0.1 to 1 AU Based on PSP, Wind, and STEREO Observations

Using the high-cadence magnetic field data from PSP (Parker Solar Probe), Wind, and STEREO (Solar Terrestrial Relations Observatory) missions, we have conducted long-term surveys of the circularly-polarized electromagnetic waves in the inner heliosphere and at 1 AU, in the frequency range near the local proton and alpha-particle cyclotron frequencies. Based on the large wave event lists from the three missions covering October 2018 March 2021, we investigate the radial evolution of the wave properties from 0.1 to 1 AU statistically, including the occurrence rate, wave frequency, wave power, etc. These waves are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame, and they often propagate in the direction near the local magnetic field. We first select the events in which LH and RH waves occur closely in time or simultaneously, and then analyze their intrinsic frequencies in the plasma frame and how the wave parameters vary with plasma conditions such as the solar wind ion temperature anisotropy and relative drift. The implication of the radial evolution of the LH and RH waves on models of solar wind heating and acceleration is discussed.