Heating and transport of metal plasma in a vacuum-arc rail gun

Arc coupled nonlinear LCR circuit equations were solved simultaneously with the Newtonian arc motion to describe the under-critically damped high arc current and resulting _J × _B propulsion in a vacuum-arc rail gun. Heating of plasma owing to the direct coupling by arc through magneto-hydrodynamic, ion-acoustic, Coulomb, and neutral interactions is formulated in a three-component electron continuity regime including major loss by radiation. The plasma density (n_e) so deduced in arc was around 10²²-10²³m^-3, temperature (T_e) over hundreds of electronvolts, and attained final velocity ∼2×10⁶cm/s. The launched plasma on emerging from the gun muzzle, rapidly equilibrated through radiative re-combinations and three-body collisions has n_e∼5×10²¹m^-3 and T_e∼80-90 eV at 50 cm away from the breech as shown through experiments.