Does this work because of the mass difference between electrons and protons?
If you separate an electron from an atom, charge is conserved, mass in conserved. Apply an electric field, then you shoot the ion one way and the electron the other. The heavy ion then acts like propellant. Mass still conserved, charge still conserved. At some point the electron is absorbed into some random ion elsewhere and the ion grabs an electron from elsewhere.
If you separate an electron from an atom, charge is conserved, mass in conserved. Apply an electric field, then you shoot the ion one way and the electron the other. The heavy ion then acts like propellant. Mass still conserved, charge still conserved. At some point the electron is absorbed into some random ion elsewhere and the ion grabs an electron from elsewhere.