Abstract: In an apparatus for accelerating electrically charged particles from a pulsed plasma reservoir of high particle density in a dielectric tubular chamber which extends from the reservoir and is surrounded by at least two electrodes of which one is disposed at the wall of the reservoir, the dielectric tubular chamber is partially evacuated to a sufficiently low pressure p such that the product of the gas pressure p and the inner diameter d of the tubular chamber is low enough to avoid parasitic discharges in the residual gas charge, and a voltage is applied to the electrodes such that the particles are drawn into the dielectric tubular chamber with high flow density and are accelerated therein thereby forming a charged particle beam whereby the residual gas charge in the dielectric tubular chamber is ionized along the inside wall of the tubular chamber and polarized such that the wall of the dielectric tubular chamber becomes repulsive for the charged particle beam and its axis becomes attractive whereby the cha