A complex plasma injection device was investigated. It consists of a coaxial plasma accelerator with gas preionization and a spatially periodic sign-changing magnetic field used to guide the high-velocity plasma stream and to separate the slow one. A high-energy plasma stream with a total energy of ≥ 160 J (4 - 4.5 × 1017 particles) and an amount of impurities not exceeding 1% was obtained at the output of the magnetic system. It is seen that the guiding magnetic field does not penetrate into the leading fast plasma puff, which implies that the connection of the injector system to the magnetic traps should be simplified when a complex plasma injector of such type is used.