Hannes Olof Gösta Alfvén
1908–1995, Norrköping, Sweden, Djursholm, Sweden
Swedish plasma physicist who founded magnetohydrodynamics and discovered the Alfvén waves propagating in magnetized plasmas.
An engineer by training at Uppsala and KTH, Alfvén realized in the 1940s that a conducting fluid threaded by a magnetic field can carry a new kind of wave. Long dismissed — the theory seemed to contradict intuition about fluids and fields — MHD was vindicated by experiments and became the framework for sunspots, the solar wind, auroras and laboratory fusion devices.
Nobel-winning work
Alfvén's 1970 Nobel Prize honored 'fundamental work and discoveries in magnetohydrodynamics with fruitful applications in different parts of plasma physics'. In 1942 he showed that a magnetic field frozen into a conducting fluid behaves like an elastic string: perturbations propagate as transverse 'Alfvén waves' at speed v_A = B/√(μ₀ρ).
The theory, verified in liquid metals in the 1950s, explains how energy and momentum are transported in the Sun's atmosphere, the solar wind, planetary magnetospheres and fusion plasmas, and underlies models of cosmic-ray acceleration and interstellar dynamics.
Workplaces: Royal Institute of Technology (KTH), Stockholm
Sweden