Quasi‐Trapped Zebra Stripes: Radial Transport Driven by Dual‐Pulse Electric Fields

Energetic electron spectra in Earth's inner radiation belt often exhibit regular stripe‐like features, known as “zebra stripes,” which are typically attributed to the drift motion of stably‐trapped electrons disturbed by electric field perturbations. Using high‐quality electron measurements from the Macao Science Satellite‐1, we report the first observation of zebra stripe structures in quasi‐trapped electrons within the inner radiation belt. Through a combination of data analysis and test particle simulations, we show that the formation of quasi‐trapped stripes follows a two‐step radial transport driven by dual‐pulse electric fields. The first electric field generates zebra stripes in the stably‐trapped region, while the second moves them further inward into the quasi‐trapped zone, where they are identified as quasi‐trapped zebra stripes. These findings offer new insights into utilizing electron observations to diagnose the morphology and temporal profile of large‐scale electric fields within the inner radiation belt.