Controlled precipitation of energetic Van Allen belt protons by electromagnetic ion cyclotron (EMIC) waves

Abstract

The high-energy protons trapped in the inner Van Allen belt are a hazard to the man-made space systems orbiting the region. We analyze the possibility of human control over these energetic particles by the transmission of electromagnetic ion cyclotron (EMIC) waves from space-based antennas. We examine the propagation of man-made EMIC waves, their interaction with the energetic inner belt proton population, and the overall feasibility of controlled proton precipitation. The nature of the interaction between EMIC waves radiated from space-based transmitters and energetic protons is different from the naturally occurring processes in the magnetosphere, the latter being dominated by gyroaveraged resonant interactions. In the case of man-made EMIC waves, we show that off-resonant interactions dominate the particles' scattering. However, our numerical simulations show that both the radiation and interaction processes are very inefficient, to the point that, with the current technology, it is not feasible to remediate the proton belt using space-based transmitters.

Radiation pattern of a ULF space-based antenna for controlled removal of energetic trapped protons

“…Therefore, our attention moves towards non-capacitive antenna types, or magnetic dipoles. The remediation of the inner proton belt would eventually require a large amount of radiated power [11], thus we will consider a coil of the largest dimensions that can be reasonably put into space with existing launch vehicles with a minimum of coil folding required. If driven in AC, this coil would have very high currents circulating around it, which will translate into a large self-inductance, L self , given by…”

“…The reasoning behind this assumption comes from the fact that the frequency required for remediation of the inner proton belt is much smaller than the proton gyrofrequency [11], thus the condition for Landau and cyclotron damping is not satisfied. Resonance cones, however, are normally associated with thermal effects, which should be reconsidered in future efforts.…”

“…Recent efforts by de Soria-Santacruz et al [11] analyzed the feasibility of applying the remediation idea to the even more energetic proton population of the inner radiation belt. The interaction with protons, however, involves a completely different technology compared to the one proposed for electron remediation, due to the difference between electron and proton gyro-frequencies, the latter being about 1800 times smaller.…”

“…The frequency of EMIC waves is below the proton gyro-frequency, and they appear in three different bands depending on the proximity of their frequency to the different heavy ion cyclotron frequencies (O + , He + , and H + bands). [11] analyzed the characteristics of the interaction between EMIC waves and energetic inner belt protons, and described the effect of the wave frequency on this process. Additionally, de Soria-Santacruz et al [10] presented a preliminary mechanical, thermal, and electrical design of the space-based antenna capable of radiating EMIC waves, which consists of a rotating coil driven with DC current.…”

“…In that paper, however, the radiation pattern and radiated power were assumed as given, and no details about their formulation and calculation were provided. Similarly, [11] focused on the physics behind the interaction between EMIC waves and energetic protons, while the radiation pattern was only qualitatively discussed and taken as a given input to the interaction models. The present paper complements the two publications mentioned above and for the first time provides the detailed formulation and methodology used to calculate the radiation pattern and radiation resistance of a DC coil antenna immersed in a magnetized plasma that rotates at the EMIC frequencies.…”