In addition to converters using electrodes, pure inductive magnetic converters have also been proposed by Lev Artsimovich in 1963, then Alan Frederic Haught and his team from United Aircraft Research Laboratories in 1970, and Ralph Moir in 1977.
The magnetic compression-expansion direct energy converter is analogous to the internal combustion engine. As the hot plasma expands against a magnetic field, in a manner similar to hot gases expanding against a piston, part of the energy of the internal plasma is inductively converted to an electromagnetic coil, as an EMF (voltage) in the conductor.
This scheme is best used with pulsed devices, because the converter then works like a "magnetic four-stroke engine":
# Compression: A column of plasma is compressed by a magnetic field that acts like a piston.
# Thermonuclear burn: The compression heats the plasma to the thermonuclear ignition temperature.
# Expansion/Power: The expansion of fusion reaction products (charged particles) increases the plasma pressure and pushes the magnetic field outward. A voltage is induced and collected in the electromagnetic coil.
# Exhaust/Refuel: After expansion, the partially burned fuel is flushed out, and new fuel in the form of gas is introduced and ionized; and the cycle starts again.
In 1973, a team from Los Alamos and Argonne laboratories stated that the thermodynamic efficiency of the magnetic direct conversion cycle from alpha-particle energy to work is 62%.