This thesis first reveals the mechanism of Goertler instabilities and then demonstrates how transitions at hypersonic flows can be effectively controlled (either promoted or suppressed) with Goertler or Klebanoff modes. It focuses on understanding and controlling flow transitions from mild laminar to fully turbulent flows at high speeds-aspects that have become crucial at the dawn of an incredible era, in which hypersonic vehicles are becoming available. Once this occurs, it will be possible to travel from Beijing to Los Angeles within just 2 hours, and we will all live in a genuinely global village-and not just virtually, but physically. Goertler instabilities have often been used to promote flow transition in hypersonic vehicles. However, how Goertler instabilities are excited and how they evolve in hypersonic flows are questions that have yet to be answered.

This thesis focuses on ULF (Ultra-low-frequency) waves' interaction with plasmasphere particles and ring current ions in the inner magnetosphere. It first reports and reveals mutual effect between ULF waves and plasmasphere using Van Allen Probes data. The differences and similarities of different ring current ions interacting with ULF waves are extensively explored using Cluster data, which provides a potential explanation for O+-dominated ring current during the magnetic storms. Furthermore, this thesis finds a method to study the phase relationship between ULF waves and drift-bounce resonant particles, and proposes that the phase relationship can be used to diagnose the parallel structure of standing wave electric field and energy transfer directions between waves and particles. The findings in this thesis can significantly promote our understanding of ULF waves' role in the dynamics of inner magnetosphere.

This thesis first reveals the mechanism of Goertler instabilities and then demonstrates how transitions at hypersonic flows can be effectively controlled (either promoted or suppressed) with Goertler or Klebanoff modes. It focuses on understanding and controlling flow transitions from mild laminar to fully turbulent flows at high speeds-aspects that have become crucial at the dawn of an incredible era, in which hypersonic vehicles are becoming available. Once this occurs, it will be possible to travel from Beijing to Los Angeles within just 2 hours, and we will all live in a genuinely global village-and not just virtually, but physically. Goertler instabilities have often been used to promote flow transition in hypersonic vehicles. However, how Goertler instabilities are excited and how they evolve in hypersonic flows are questions that have yet to be answered.