Design of a MITL for a 1 MA LTD driving a wire array z-pinch load

A self-magnetically insulated transmission line (MITL) has been designed to transmit a 1 MA, 100 kV pulse with a 100 ns (10%–90%) rise-time from a Linear Transformer Driver (LTD) to a wire array z-pinch load. The transmission line has three stages: a coaxial line, followed by a radial line, and finally a conical line to the load. This transmission line geometry was chosen to ease construction and to lower cost while maintaining a low inductance. A collisionless magnetic insulation model was used to determine the lower limit of the anode-cathode gap for the transmission line. Additional designs were investigated assuming vacuum insulation with limiting electric fields of 100 kV/cm and 200 kV/cm in the transmission line. The transmission line inductance in each of these cases was calculated analytically, and a PSpice simulation of the circuit was used to compare the performance of the designs. Assuming the z-pinch load inductance was approximately 3 nH, the collisionless magnetic insulation model met the goal of a 1 MA pulse with a 100 ns rise-time. The vacuum insulation designs did not meet these requirements. The anode-cathode gap in the magnetic insulation design was expanded such that the current pulse shape still met the design goals and a safety factor was added to reduce the possibility of arcing. This MITL design will be constructed and implemented on the Michigan Accelerator for Inductive Z-pinch Experiments (MAIZE) being constructed in 2007 at the University of Michigan.