Behavior of azimuthal currents induced in the projectile of the linear induction launcher [LIL]

The performance of a two-section three-phase capacitor-driven linear induction launcher (LIL) is analyzed by means of a computer simulation code which is based on the transient behavior of a lumped circuit model representing the gun. The reliability of the code was tested previously by comparison with experimental work, as was reported earlier. Initially, to design this launcher, to select dimensions and to do preliminary calculations of performance, simple steady state sinusoidal operation was assumed. (This is similar to startup of a classical induction motor, in which the mechanical time constants are much longer than the electrical ones.) However, when the dimensions were entered into the code, the code-predicted performance differed from the results obtained using the simplistic model. This paper explains that the reasons for most of the departures from the sinusoidal steady-state can be understood by taking into account four hurdles that prevent its attainment: (1) single phasing, (2) frequency mixing, (3) damping, and (4) sectionalization.