ET-GUNS WITH WORKING MEDIA OF LOW-MOLECULAR-WEIGHT - A NUMERICAL STUDY

Numerical simulations of the electrothermal acceleration process have been carried out in order to assess the potential of different working media. For some interesting substances the mass/energy ratio and the total dissipated energy are varied in the computations. A comparison t o conventional powder guns is made for a small calibre (bore diameter a = 20 mm) weapon. Using SESAME equations of state, a good efficiency is predicted for hydrogen, helium and polyethylene and a medium one fo r lithium vapor. For muzzle velocities around 1500 m/s, ET guns show s imilar characteristics as chemical guns. Approaching 2500 m/s, the max imum gas pressure in the ET gun is decisively smaller, With a tolerabl e pressure of 500 MPa, the hydrogen gun can accelerate a mass of 100 g to nearly 2000 m/s in a barrel length of 2.25 m (2300 m/s in 4.25 m).