EMACK improvements, present and future

A three-step program has been developed to improve the single-shot performance and to add 1-Hz repetitive operation capabilities to the EMACK electromagnetic launcher system. Single-shot performance is improved in two steps: first by copper-plating the HPG (homopolar generator) rotor, increasing the switch shuttle surface area, and developing a stronger barrel; and then by augmenting the inductive store support structure to withstand the increased electromagnetic forces at higher current, modifying the HPG rotor with a Be-Cu sleeve, and adding a flywheel. These modifications will allow operation of the system at a peak current of 2.2 MA. Repetitive operation of the system is gained by significantly modifying the linear rail switch to accommodate multiple shuttles, adding a repetitive loader, and cooling the muzzle and dump resistors. Larger masses could be accelerated by increasing the size of the flywheel. Repetitive operation of the EMACK launcher at frequencies in the neighborhood of 1 Hz is made possible by using a high-resistance muzzle resistor to drop the HPG current to a low value between shots