Roald Zinnurovich Sagdeev (born 26.12.1932) — a Soviet physicist, academician (1968, corresponding member 1964). Born in Moscow. He graduated from Moscow University (1956). In 1956 — 61 he worked at the Kurchatov Institute of Atomic Energy, in 1961—70 —as head of a laboratory at the Institute of Nuclear Physics of the Siberian Branch of the USSR Academy of Sciences (Novosibirsk), and in 1970 — 73 at the Institute of High Temperatures of the USSR Academy of Sciences. Since 1973 he has been director of the Space Research Institute of the USSR Academy of Sciences.
His work was in plasma physics, the problem of controlled thermonuclear fusion, magnetohydrodynamics and space physics. He carried out research on the theory of plasma stability, the physics of nonlinear oscillations and turbulence of plasma, and plasma dynamics. In 1964 he discovered collisionless shock waves and created qualitative ideas about the propagation of strong discontinuities in plasma. He carried out important research on the theory of tokamak magnetic traps, in particular, together with A. A. Galeev, he developed the neoclassical theory of heat conduction and diffusion in tokamaks (1967 — 68). Independently of M. Rosenbluth he discovered (1958) the fire-hose instability in plasma. He predicted (1960) an electromagnetic instability of the type of the build-up of whistlers in a hot electron plasma.
Member of the International Academy of Astronautics (1977).