Efficient production of strong magnetic fields from ultraintense ultrashort laser pulse with capacitor-coil target

An ultraintense femtosecond laser pulse was used, for the first time, to produce a strong magnetic field with controlled shapes by interactions with a capacitor-coil target with high efficiency. The temporal evolution of the strong magnetic field was obtained by the time-gated proton radiography method. A comparison of high-resolution radiographic images of proton deflection and particle-track simulations indicates a peak magnetic field of ∼20 T. The energy conversion efficiency from the ultraintense laser pulse to the magnetic field is as high as ∼10%. A simple model of the ultraintense laser-driven capacitor-coil target gives a relationship between the magnetic field strength and the electron temperature produced by the laser. Our results indicate that magnetic fields of tens of tesla could be stably produced by most of the existing ultraintense laser facilities. It potentially opens new frontiers in basic physics which require strong magnetic field environments.