Progress on Liner Implosions for Compression of FRC's

Magnetized Target Fusion (MTF) is a means to compress plasmas to fusion conditions that uses magnetic fields to greatly reduce electron thermal conduction, thereby greatly reducing compression power density requirements (1,2). The compression is achieved by imploding the boundary, a metal shell. This effort pursues formation of the Field Reversed Configuration (FRC) type of magnetized plasma, and implosion of the metal shell by means of magnetic pressure from a high current flowing through the shell. We reported at Megagauss 9 that we had shown experimentally (3) that we can use magnetic pressure from high current capacitor discharges to implode long cylindrical metal shells (liners) with size, symmetry, implosion velocity, and overall performance that is suitable for compression of Field Reversed Configurations (FRC's). We also presented considerations of using deformable liner - electrode contacts of Z-pinch geometry liners or theta pinch driven liners, in order to have axial access to inject FRC's and to have axial diagnostic access. Since then, we have experimentally implemented the Z-pinch discharge driven deformable liner - electrode contact, obtained full axial coverage radiography of such a liner implosion, and obtained 2D-MHD simulations for a variety of profiled thickness long cylindrical liners. The radiographic results indicate that at least 16 times radial compression of the inner surface of a 0.11 cm thick Al liner was achieved, with a symmetric implosion free of instability growth. We have also made progress in combining 2D-MHD simulations of FRC formation with imploding liner compression of FRC's.