A stochastic cyclotron ion filter for separating ions in a multi-species plasma according to mass uses an electrical field (E) crossed with a magnetic field (B). In particular, the electric field is stochastically generated by an amplified noise source with a band pass filter that passes only frequencies in an interval between ω 1 and ω 2 . The filter also includes a cylindrical chamber for receiving the multi-species plasma, and coils are used to generate the magnetic field inside the chamber. In operation, the stochastically generated electric field resonates with particles in the plasma that have a cyclotron frequency Ω in the frequency interval (ω 1 2 ). In one embodiment, an electrode is mounted at one end of the chamber, and the electrode is connected with the amplifier to establish the electrical field in the chamber. In another embodiment, an electromagnetic coil is mounted on the chamber and is connected with the amplifier to induce the electrical field in the chamber. For both embodiments, particles having resonant cyclotron frequencies Ω in the frequency interval (ω 1 2 ) are accelerated into larger orbital paths than other particles in the plasma and, thereby, are separated for collection.