Vacuum Magnetic Field Compression

Experiments using MIFEDS 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).