Magnetohydrodynamic drive

Called a magneto hydrodynamic drive, even MHA (English magneto hydrodynamic drive, MHD), is a driving principle for watercraft.

One can consider such a device as a reversal of the magneto- hydrodynamic generator: not the moving water generated in the magnetic field a current between the collector plates, but the current in the magnetic field sets the water in motion.

As for locomotion no propeller or other moving parts are used, the drive is virtually silent.

There were already working prototypes to be built in the U.S., as well as in Japan, the necessary high magnetic flux densities and electric currents make the operation unprofitable, however.

Operation

Perpendicular to the desired direction of movement and perpendicular to each other, an electric and a magnetic field to be established. The electrolysis of water produces a current in the direction of the electric field, the charge carriers are deflected by the Lorentz force in the magnetic field. This means that the water is along the jet direction in movement, the recoil drives the ship.

The Lorentz force on a conductor of length d, through which a current I flows, is in the magnetic field strength B

Here where d represents the distance between the electrodes. The available driving force is itself only relatively low magnetic fields of several Tesla and currents of several thousand amperes.

Prototypes

1966, the first MHA drive in a model submarine, the EMS -1, off the coast of California has been successfully tested.

In the 1980s and 1990s were in Japan, including Mitsubishi, models and prototypes MHA - powered ships constructed (for example SEMD -1, ST -500). The vehicles reached speeds of about 15 km / h, although numerous difficulties arose.

In June 1992, the experimental ship ( crew 30 m long, 10 m wide, displacement 185 t, ten people ( three crew members and seven passengers ) ), was the Yamato 1 tested at the port of Kobe. The vessel was mostly made ​​of an aluminum alloy (JIS A 5083 ) and driven by two magnetohydrodynamic engines. The drive system functioned similar to a water jet propulsion: sea water was ejected accelerated here by means of the Lorentz force on the stern of the ship. The magnetic fields required for this purpose have been generated by the cooled with liquid helium niobium / titanium superconductor.

It thereby magnetic flux densities of 4 Tesla were used. The Yamato 1 is now located in front of the Naval Museum in Kobe.

Drive concept also in space

Conceptually analogous to, but working with the plasma medium, the magneto- plasma- dynamic propulsion for space vehicles is an active subject of research.

Trivia

In the movie The Hunt for Red October, a MHA 1990 was discussed, which could propel a novel, fictional submarine silently. In contrast to this film, the original literary themed a submarine with a water jet propulsion.

In several books by Clive Cussler there are ships and submarines with magneto hydrodynamic drive. In the books of the Oregon - Oregon series is equipped with this drive.