The invention relates to a novel electric capacitor for the attainment of very high voltages and for the storage of electric energy, comprising of two concentric coaxial toroidal conductors with the inner conductor levitated, an external magnetic field coil, a thermionic cathode emitting electrons, a levitated guide electrode and a discharge tube. The stored energy can thereby be delivered in form of atomic particle beams or electromagnetic waves especially electron beams in very short times and thus with very high power. Applications are: (1) the initiation of nuclear reactions, especially thermonuclear reactions, (2) the collective acceleration of electrically charged atomic particles to very high energies, (3) Gamma-ray flash tubes, (4) the pumping of lasers, (5) micro wave pulse generators and (6) the use of the thusly generated radiation for medical purposes.