Railgun launch of small bodies

Small body launching using gas or plasma faces the fundamental problem caused by excess energy loss due to great wall surface/volume of the barrel ratio. That is why the efficiency of the plasma armature (PA) railgun acceleration is maximum for 8-10 mm-size bodies and drops as their size decreases (see Drobyshevski et al., Sov. Phys. Tech. Phys. vol. 36, no.8, p.903, 1991). For the nuclear fusion applications, where #1-2 mm-size pellets at 5-10 km/s velocity are desirable, one is forced to search for compromise between the body size (3-4 mm) and its velocity (3 km/s). Under these conditions, EM launchers did not demonstrate an advantage over the light-gas guns. When elaborating the #1 mm railgun, we made use of our ideology of the body launching at constant acceleration close to the body strength or the electrode skin-layer explosion limits (see Drobyshevski, et al., Sov, Phys. Tech. Phys. vol.36, no.4, p.469, 1991). That shortened the barrel length sufficiently. The system becomes highly compact thus permitting rapid testing of new operation modes and different modifications of the design including the magnetic field augmentation. As a result of these refinements, the difficulties caused by the catastrophic supply of mass ablated from the electrodes were overcome and regimes of #1 mm body speed-up to 4.5 km/s were found. Potentialities of the small system created are far from being exhausted.<
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