The basics for thermonuclear fusion research were laid in 1905 by Albert Einstein and by Francis William Aston, who calculated in 1920 that four protons could fuse into a helium nucleus, releasing energy. Fusion was first achieved in a thermonuclear bomb (Ivy Mike, 1952). A true controlled thermonuclear fusion reaction was reached in 1958 on the theta-pinch device Scylla-I. The stellarator principle was used in Lyman Spitzer's Model A Stellarator in 1953, and the tokamak T-1 started operation in 1958 in Russia. Construction of ITER, the largest tokamak ever built, started in 2007. On December 5, 2022, the laser-driven fusion facility NIF achieved the ignition state for the first time.