[en] The major problem studied here has been the propagation of the high current, high energy, but unguided ion beam across the 5 to 10 m radius target chamber onto the 1 mm target. If the target chamber pressure is less than 10^-5 torr, number density n < 10¹² cm^-3, the beam propagates as though in vacuum, and in a low enough charge state even an unneutralized beam should reach the target ballistically. At pressures > 10^-4 torr, the high value of the cross section for ionization of the beam particles sigma = 10^-16 to 10^-17 means that the beam charge state grows while the background gas is ionized. As a result the beam is charge neutralized and to a large extent, current neutralized; however, a two stream instability is excited and the electric fields produced seem great enough to deflect the beam by about 1 mm, enough to miss the target