Abstract—A method of designing a thermonuclear reactor based on the modified Cockroft–Walton accelerator, where the lithium–proton fusion was first observed, is considered. It is proposed that the reactor have the form of a spherical capacitor with a point lithium cathode used as the inner electrode and a spherical anode, as the outer electrode. The interelectrode space is filled with hydrogen. A high-voltage electric pulse applied to the electrodes is used as a driver. The reactor parameters providing an ion temperature of 100 keV and a proton flux of 8.6 x 10^15 W/cm2to the cathode are determined. The basic elements of a system generating thermonuclear fusion energy, including those of the energy conversion chamber with a fusion chamber inside, are listed, and possible applications of the system are indicated.