Experiments using MIFEDS [MIFEDS page] have demonstrated record magnetic field compressions, reaching fields of from initial magnetic fields of ~10 T. These magnetic fields, however, can only be applied to a compressed plasma; studying the physics of highly magnetized laser plasmas requires generating such fields in vacuum where another experiment may be placed. Laser-driven coils were claimed to generate kT magnetic fields, but detailed studies by the Innovative Concepts Group demonstrated that this is impossible 1. Therefore, we are now studying vacuum magnetic field compression of seed fields generated by MIFEDS. The axial magnetic field in a cylindrical compression need not be embedded in a plasma since the physical mechanism is compression of the current loop generating the field, which can be at a plasma–vacuum interface. We are studying three approaches to vacuum magnetic field compression; (1) compress a hollow cylinder by ablating the outside, (2) ablate a plasma from the inside of a cylinder or half-cylinder, and (3) eject electrons from a cylinder by irradiating it with a short-pulse, high-intensity laser pulse. We have obtained preliminary experimental results for (1) and (2) (see figure), and carried out MHD simulations of (3).
VISRAD design of an experiment using a short-pulse laser to eject electrons from a cylinder (left) and an axial proton radiograph of a similar experiment at 10 ps, for a 1-ps laser pulse showing electron ejection from the inner surface (right). Experiments with an applied magnetic field are planned.