Fig. 1: The Thunderbird Reactor.

a, Working principle of the Thunderbird Reactor. Deuterium gas (D₂) is fed to the plasma thruster through the deuterium gas inlet. The D₂ is ionized by a microwave source. Plasma thruster magnets expel the resultant plasma of D⁺ and e⁻ into the vacuum chamber. A −30-kV voltage applied across the palladium target and the vacuum chamber creates a plasma sheath enriched in D⁺ and accelerates the D⁺ into the palladium target, where nuclear fusion can occur. On the opposite side of the palladium target is an electrochemical cell that oxidizes OD⁻ into D₂O and O_2(g) at the anode. The D₂O is reduced to D at the palladium target, which acts as a cathode. The D is then absorbed into the palladium target to potentially fuse with D sourced from the plasma thruster. The plasma current is set at 0.5 mA by the power supply and a galvanostat maintains a constant current of 200 mA across the anode and cathode of the electrochemical cell. b,c, Photographs of the Thunderbird Reactor (b) and the electrochemical cell (c). Scale bars, 10 cm (b); 2.5 cm (c).