How to add sharpness to the blade using a plasma arc?

Original author: Dan Maloney
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If I ask you now what technology you would like to see from films and books about science fiction, I assume that most of you will answer - plasma swords from Star Wars. Agree, there is something to lightly press the button to release blades of bright colors from a small handle, to melt metal and fight against enemies on distant planets, waving a weapon with such a familiar and familiar buzz.

If you are at least a little fan of this bestseller or are interested in making fantastic things come true, then this Friday post is for you.

Much to our regret, the day when we can shape our plasma in the form of a personalized lightsaber is quite far away. The main characteristic of a plasma is that it consists of electrically charged particles. They are ionized, and can actually conduct electricity. Nowadays, plasma is an incredibly hot thing, which is why it is so often used as a blade in many fantastic stories. In the sci-fi universe, if the plasma is heated to a sufficient temperature, it can ignite or melt solid objects.

The most common explanation for how you can get a plasma blade is that the plasma produces a magnetic field that works because the plasma is made from charged particles and the charged particles are exposed to a magnetic field, especially if it is positive. charged particles moving in a certain direction. In a magnetic field that moves in the opposite direction, the particles will be under the influence of the Lorentz force. That is why you can control the shape of the blade. All these different directions and forces are called the right-hand rule. In practice, we have a neodymium magnet on one side of the transformer, and an ordinary copper electrode on the other. The Lorentz forces must shape our arc in the form of a correct and recognizable cone-shaped sword from the Star Wars universe.

The best example of directed plasma in real life is the Wendelstein 7-X (W7-X) reactor, which is an experimental stellarator built in Greifswald, Germany.

It forms a complicated donut-shaped plasma plasma and contains it in 70 superconducting magnets with cooled helium. In a nutshell, this is really crazy stuff. The plasma inside can reach temperatures of 55.5 million degrees Celsius ( for reference, the core temperature of our Sun is 15 million degrees Celsius). At the same time, superconducting magnets must be cooled to -270 degrees Celsius, which is a couple of degrees above absolute zero. These two temperatures are at a distance of 30 centimeters from each other. This is approximately the length of A4 paper. Now imagine that on the one hand you have something that is about 3 degrees warmer than the absolute coldest temperature in the whole universe, and on the other hand you have a temperature that is about 4 times higher than in the core of the Sun, and your head would easily fit between these two extremes.
All of the above, however, did not stop Allen Pen from creating a hand-held plasma cutter.

The difficult thing about plasma formation and containment with this method is that you need an incredibly powerful and really strange form of magnetic field to make a blade. In addition, everything that you have would have to be attached to the superconducting magnets inside, and then somehow project this magnetic field half a meter away, while usually the magnetic field strength exponentially decreases with distance. Therefore, Allen Peng actually prefers metal blades with plasma edges. It is much easier to imagine and apply the mechanism in which the plasma would be created and formed in a couple of centimeters from the carrier, and not at a distance of half a meter.
Allen has no superconducting magnets, so he will not be able to use magnetic fields, especially since his blade would need a plasma that is cooler than 55.5 million degrees Celsius.

What he does is use his Ladder Sam Jacob, only this time he adds an electric fan, thereby the air hose inflates the necessary air directly between the two electrodes. An electric arc ionizes the air flow and creates a really cool looking sheet of coronal plasma between two electrodes, which is called non-thermal or arc plasma. In industry, this method is used to sterilize surfaces or prepare them for painting. I think it looks like a sweet plasma dagger.

It is assumed that it is possible to expand the blade with a higher voltage and a smoother laminar air flow, but for now the mechanism is more suitable for a plasma machete, and not for the sword. When using a plasma blade, the equipment is slightly similar to the equipment of the character Ghostbusters - non-compact and inconvenient, because at the moment the best way to supply air to the blade is a blower. Of course, in the future, people will be able to include this arsenal in the squad to protect the planet, create a mini-jet engine to help them, and the design of the sword itself will probably be much easier and more compact. But this is all later.

IMPORTANT: The fact that in this type of blade, the plasma is not as hot as in the reactor, does not mean that it is safe, so in no case do not try to repeat it at home.

Finally the video:

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