Particle-Trapping Injection Flux Tubes in Saturn's Magnetosphere and High-Band Electron Cyclotron Harmonic Waves Therein

Injection flux tubes, characterized by localized equatorial magnetic field enhancements and concomitant hot plasma populations, contribute to Saturn's magnetospheric convection cycle by transporting magnetic flux radially inward. The sharp magnetic gradients at the flux-tube edges have been demonstrated to enable the trapping of equatorially mirroring particles, leading to their energy-dispersionless signatures in spacecraft observations. Here, we present a statistical distinction between flux tubes with and without particle-trapping features in the electron cyclotron harmonic (ECH) wave properties. The particle-trapping flux tubes carry stronger ECH waves in the high-harmonic bands, whereas the other category is usually accompanied only by fundamental-mode waves. This distinction is largely attributed to the higher content of energetic electrons within the particle-trapping flux tubes. These results improve our understanding of the association between injection flux tubes and the high-band ECH waves therein, suggesting a unique role of particle-trapping flux tubes in Saturnian magnetospheric dynamics.