Masaaki Yamada (Japanese: 山田雅章, Hepburn: Yamada Masaaki, born August 9, 1942 in Japan) is a Japanese plasma physicist known for his studies on magnetic reconnection. Yamada obtained a bachelor's degree in applied physics at the University of Tokyo in 1966 and a master's degree in nuclear engineering in 1968, and received a doctorate in physics from the University of Illinois in 1973. He was then at Princeton University and from 1978 at its Princeton Plasma Physics Laboratory (PPPL), where he led the development of the Spheromak S-1, a compact toroidal device for plasma confinement from 1978 to 1988, which was investigated for some time as an alternative to the Tokamak. He has been a Principal Research Physicist at the PPPL since 1982 (2015 he is a Distinguished Laboratory Research Fellow).