a toroidal reactor used in thermonuclear experiments, in which a strong helical magnetic field keeps the plasma from contacting the external walls. The magnetic field is produced partly by current-carrying coils and partly by a large inductively driven current through the plasma
Word origin
C20: from Russian to(roidál'naya) kám(era s) ak(siál'nym magnitnym pólem), toroidal chamber with magnetic field