Creation of a uniform high magnetic-field strength environment for laser-driven experiments

Measurement of magnetic fields generated by a high-energy, high-intensity laser-driven millimeter-scale Helmholtz coil target is reported. The magnetic field is derived from a reverse current that passes through two coils of 1.25-mm radius. A peak field of 7 T with a time decay of 17 ns is inferred from a series of induction coil measurements when the hot-electron temperature driving the reverse current is approximately ~15 keV. A simple model of the laser-driven Helmholtz coil target suggests how the target should be optimized to produce high-peak fields and indicates that peak magnetic fields above 100 T are accessible. This could lead to exciting experiments in laser-plasma physics, in particular, experiments related to laboratory astrophysics.