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Abstract Drift periodic echoes of electrons in the inner belt appear as structured bands in energy spectrograms, also known as “zebra stripes”. Such phenomenon is normally observed at energies from 10s of keV to ∼250 keV. We report multiple series of zebra stripes of relativistic electrons observed by the recent Colorado Inner Radiation Belt Experiment (CIRBE) CubeSat. The high energy resolution measurements taken by the REPTile‐2 (Relativistic Electron and Proton Telescope integrated little experiment‐2) instrument onboard CIRBE show that zebra stripes of radiation belt electrons can be observed from 300 keV to >1 MeV, crossing theLrange from 1.18 to >3, from quiet times to storm times. Through test particle simulations, we show that a prompt electric field with a peak amplitude ∼5 mV/m in near‐Earth space can trigger zebra stripes of relativistic electrons. Azimuthal inhomogeneity of electron distribution caused by the prompt electric field modulates the electron energy spectrum by energy‐dependent drift phases to form zebra stripes. Though zebra stripes are observed in both belts, they tend to last longer and appear more frequently in the inner belt. Zebra stripes in the outer belt will have a shorter lifetime due to more perturbations there, including energy and pitch‐angle diffusion, which diminish the structure. This study demonstrates the important role of electric fields in the dynamics of relativistic electrons and contributes to the understanding of the mechanisms creating and diminishing zebra stripes. 

Abstract Following the largest magnetic storm in 20 years (10 May 2024), REPTile‐2 on NASA's CIRBE satellite identified two new radiation belts containing 1.3–5 MeV electrons aroundL = 2.5–3.5 and 6.8–20 MeV protons aroundL = 2. The region aroundL = 2.5–3.5 is usually devoid of relativistic electrons due to wave‐particle interactions that scatter them into the atmosphere. However, these 1.3–5 MeV electrons in this new belt seemed unaffected until a magnetic storm on 28 June 2024, perturbed the region. The long‐lasting nature of this new electron belt has physical implications for the dependence of electron wave‐particle interactions on energy, plasma density, and magnetic field strength. The enhancement of protons aroundL = 2 exceeded an order of magnitude between 6.8 and 15 MeV forming a distinct new proton belt that appears even more stable. CIRBE, after a year of successful operation, malfunctioned 25 days before the super storm but returned to functionality 1 month after the storm, enabling these discoveries.