Transition armature technology. Progress report No. 2, August 1--September 30, 1991

Abstract

This second report covers the period August 1 to September 30, 1991. During this period we modified our approach to Task 1 (Hybrid Armature study) with the addition of a numerical simulation of the steady state plasma brush length with a 1-D, four-phase equation of state code. A test fixture was designed and fabrication begun on a plasma brush test fixture for hybrid studies. It will be powered by a 140 kJ, 1 MA capacitor bank on loan to the project. Diagnostic data collection with 20 channels of digitizers and data reduction with a microvax were also arranged. Sliding friction of a solid armature was simulated and found to form a vapor layer at velocities below 2 km/s. The simulations indicated that higher interface pressure results in vapor boundary layer formation at lower velocity. If there is also a minimum interface pressure required to commutate high currents, then an optimum interface pressure will probably result. Plans for a launcher test bed were begun in preparation for performing dynamic validation tests of the simulated predicted performance of both solid and hybrid armatures. Components of an 8 module, 600 kJ, 5 kV, 1 MA capacitor bank has been moved into the railgunmore » testing lab. The bank will be capable of powering advanced concept, multi-rail launchers. The same diagnostic and data reduction system described above will be shared. Launcher test bed alternatives are under review. Four (Quadra) and six (Hexa) rail launchers have been modeled and appear to be able to provide a high impedance and lower current launcher. A mock up will be built and used for validation measurements.« less