Scaling Laws For Plasma Armatures in Electromagnetic Launchers

This paper presents an analysis performed for the purpose of developing a set of scaling relationships for plasma armatures in electromagnetic launchers. By employing curve fits of electrical conductivity and radiation mean free path variations with temperature and pressure in dense plasma armatures, we use steady-state armature analyses to develop simple scaling laws for several important plasma properties. We find that the electrical conductivity of a plasma armature can be scaled as a relatively strong function of current per unit rail height in the launcher and a weak function of launcher geometry. This result leads to a simple scaling for the voltage drop across the plasma armature. Relationships are also presented for the average armature temperature and pressure. The scaling laws developed in this paper are shown to agree very well with experimental data over a wide range of electromagnetic launcher operating conditions. These results can be useful for engineering calculations involving plasma armatures.