Compressing magnetic field into a high-intensity electromagnetic field with a relativistic flying mirror

Ultrahigh electromagnetic fields (≥~1023 W cm−2) are necessary for the study of strong-field quantum electrodynamics (QED). In this study, for the first time, we propose the compression of a pre-seeding static magnetic field with a relativistic flying mirror to generate a high electromagnetic field. The produced field intensity can be further amplified to be 5 × 1023 W cm−2 owing to the multiple reflections between the flying mirror and a stationary solid target; this produced field intensity is approximately four orders of magnitude larger than that of the seeding field and far exceeds that of the driver laser field (9.6 × 1022 W cm−2). Therefore, the ultrahigh electromagnetic field can significantly facilitate strong-field QED effects such as high-energy gamma photon emission. An analytical theory is developed to self-consistently describe the motion of the flying mirror and the field amplification. The predications from the theory are well demonstrated by numerical simulations. The scheme of producing high-intensity electromagnetic fields proposed in this letter provides a new, powerful means to study strong-field QED with a relatively low laser intensity.