In the 1944 SF story "Off the Beam" by George O. Smith, an electron gun is constructed along the length of a spaceship. In order to avoid being constrained by a net charge imbalance, it is built to also fire matching protons in the other direction, dissipating the mass of the "cathode".
With current knowledge, is this plausible? That is,
- Can a practical (i.e., not built with unobtanium insulators) electrostatic device like an electron gun separate and accelerate electrons and protons in this manner?
- Can it actually disassemble solid matter? If so, how does the composition of the cathode affect the difficulty?