How a Star Wars plasma lightsaber could work

Light saber


Star Wars is an awesome feat of the imagination. Since George Lucas first came up with his tale of honour and derring-do set in a galaxy far, far away – more than three decades ago – the tale has become an integral part of Western film-going culture. Among hovering landspeeders, blaster guns, hyperspace travel and the Death Star, the lightsaber is one of the most iconic flights of fancy. But how might it actually work?

The problems with lasers

For a start you’d need something to reflect the light beam’s end, otherwise it would simply keep on going. The lightsaber wouldn’t make any noise. And the beam wouldn’t bounce off another, similar beam, no matter what colour it was because (as you know) light has no mass or substance.

What about plasma weapons?

The idea of a lightsaber as a controlled plasma (rather than laser) weapon seems more plausible, according to Dr Michio Kaku, Professor of Theoretical Physics at the City College of New York. He develops concepts for how science fiction ideas might work in real life (and you’ve got to admit, that’s a pretty cool job), and one of his projects is a working lightsaber (watch the video for more details).

The beam

In Dr Kaku’s design, a titanium fan at the end of the lightsaber pushes 100 cubic feet of air per second through the hilt, where it’s super-heated to produce a charged gas cloud, or plasma, at 6000cËšF .

An electromagnetic coil stops the plasma from leaking and also produces the distinctive humming sound we associate with a lightsaber. The characteristic beam shape is created by a telescopic ceramic rod that shoots out of the handle.

The rod is pierced with tiny holes that allow the plasma to form a layer around it, a layer that can cut through virtually anything. The design is similar to that of plastic lightsaber toys, but the difference is that this ceramic rod would be able to withstand the kind of heat you get near the surface of the sun.

The power source

But for such an ‘elegant weapon’, a lightsaber would need an absolute beast of a power source: the equivalent of a nuclear reactor, or about 50 megawatts. One possibility for the power source is trillions of carbon nanotube batteries, small enough to wrap around the inside of the handle. To give you an idea, one nanotube is 20,000 times thinner than a human hair. Under certain conditions, carbon nanotubes actually produce electricity, a phenomenon known as thermopower. This, combined with the fact that they can conduct 1000 times more electricity than copper, make them ideal material for tiny batteries. Together, Dr Kaku reckons trillions of these nano batteries arranged in plates could produce the huge amounts of energy needed to generate superheated plasma.

The timescale

Dr Kaku thinks the technology to build a real lightsaber could be with us in the next 50 years – just in time for another Star Wars anniversary.


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