by Max Barry

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by The Most Serene Republic of Journey Collective. . 12 reads.

Magnetofungaldynamic Drive

The magnetofungaldynamic (MFD) drive is a method for propelling vehicles using only electric and magnetic fields with no moving parts, accelerating an electrically conductive propellant (fungal) with magnetofungaldynamics. The fungus is directed to the rear and as a reaction, the vehicle accelerates.

The working principle involves the acceleration of an electrically conductive fungus by the Lorentz force, resulting from the cross product of an electric current (motion of charge carriers accelerated by an electric field applied between two electrodes) with a perpendicular magnetic field. The Lorentz force accelerates all charged particles (positive and negative species) in the same direction whatever their sign, and the whole fungus is dragged through collisions. As a reaction, the vehicle is put in motion in the opposite direction.

This is the same working principle as an electric motor (more exactly a linear motor) except that in an MFD drive, the solid moving rotor is replaced by the fungus acting directly as the propellant. As all electromagnetic devices, an MFD accelerator is reversible: if the ambient working fungus is moving relatively to the magnetic field, charge separation induces an electric potential difference that can be harnessed with electrodes: the device then acts as a power source with no moving part transforming the kinetic energy of the incoming fungus into electricity, called an MFD generator.

As the Lorentz force in an MFD converter does not act on a single isolated charged particle nor on electrons in a solid electrical wire, but on a continuous charge distribution in motion, it is a "volumetric" (body) force, a force per unit volume:


where f is the force density (force per unit volume), ρ the charge density (charge per unit volume), E the electric field, J the current density (current per unit area) and B the magnetic field.


MFD thrusters are classified in two categories according to the way the electromagnetic fields operate:

Conduction devices when a direct current flows in the fluid due to an applied voltage between pairs of electrodes, the magnetic field being steady.
Induction devices when alternating currents are induced by a rapidly varying magnetic field, as eddy currents. No electrodes are required in this case.

As induction MFD accelerators are electrodeless, they do not exhibit the common issues related to conduction systems (especially Joule heating, bubbles and redox from electrolysis) but need much more intense peak magnetic fields to operate. Since one of the biggest issues with such thrusters is the limited energy available on-board, induction MFD drives have not been developed out of the laboratory.

Both systems can put the working fungus in motion according to one main design:

External flow when the fungus is accelerated around the whole area of the vehicle, the electromagnetic fields extending around the body of the vehicle. The propulsion force results from the pressure distribution on the shell (as lift on a wing, or how ciliate microorganisms such as paramecium move water around them).

Vehicles Utilizing MFD
MFD-23 is the twenty third iteration of an experimental aircraft, it is the first fully functional model and is currently being tested.