World's Strongest Magnet!

- This is the

strongest

magnet

in the

world

, capable of sucking objects and generating electric current. Can you see that? And levitate non-

magnet

ic objects. It even wreaks havoc on photographic equipment. - The cable is magnetic! - So if it's a CMOS sensor, the electrons just can't find their way. - Well, they are redirected. - So yes, if you notice that the video or audio is bad, know that it is incredibly difficult to film in these magnetic fields. A portion of this video was sponsored by Google. I arrived at the National High Magnetic Field Laboratory in Tallahassee, Florida, where since 2000 they have held the Guinness World Record for the

strongest

continuous magnetic field. - Someone left a chair where it shouldn't be.

He then sped across the cell, completely ripping the insides out of the chair. Now we all have those nice, super uncomfortable wooden chairs. - For reference, the Earth's magnetic field is 0.00005 Tesla. A refrigerator magnet weighs about 0.01 Tesla. MRI machines can obtain up to three Tesla. But this electromagnet creates a magnetic field of 45 Tesla, that is, almost a million times the Earth's magnetic field. To achieve this field, the magnet consists of an outer superconducting magnet and an inner resistive magnet. I'll explain why you need both types in a moment. The apparatus is two stories high, but the maximum field, or center field, only occurs in the center of a narrow cylinder passing through the middle. - Right now it's off. - It is? - There is no magnet. - Can I put my finger in the hole?

Is it a bad idea? - Not well. You can totally do that. - I'll see. Oh. That's where there are 45 Tesla. - Below. One meter away from that. - One meter lower. And that only falls a couple of meters? - It's clear until the end. - Oh, wow. - The maximum field is basically one centimeter high. - Yes. - We have very small samples here. Think of something like a chip in a computer or cell phone. That's what users will bring. That's pretty important for what we want to do with materials science or kinetic matter research. - Since we cannot see or film in the center of the magnet, we are going to experiment with the magnetic field that extends above and around the magnet on this platform.

So the magnet is there? - Yes. - But the magnetic field extends here. - Yes. - And past. This is known as a fringe field and although it is much weaker than 45 Tesla, it is still quite dangerous. - For a superconducting magnet, it depends on the size of that hole. So, the larger the inner diameter, the larger the marginal field, because the magnetic flux does not penetrate the windings. And you have to form a complete loop. Then those loops just move further and further outward to form that field. This is the 100 Gauss line for the marginal field. - So what happens to objects around the 100 Gauss line? - Things with shapes will begin to orient towards the field.

So if you have it on a table, for example here, it will start to spin on its own. And if you bring it much closer, it will just disappear. And by the time you notice it's moving, it's too late. That is, there are no ferromagnetic objects within the 100 Gauss line. If you have something ferromagnetic, an implant that is metallic. Pacemaker? Any? Any? Any? Well. - Bringing this magnet to maximum power takes about an hour and a half. This is because they have to put 47,000 amps of current into the external superconducting electromagnet. 47,000 amps. - 47,000 amps, 500 volts. - It's crazy. - Very good, then let's go to the full field. - One thing that happens in a strong magnetic field, obviously, is that magnetic materials are attracted to it.

We opened up a Nerf football and put a couple of steel washers on it, being careful to cover it with tape so the washers can't come off. We also cover the opening of the magnet so that the ball does not get absorbed by it. I have an unmodified Nerf soccer ball. And sure enough, it's easy to tell which ball contains the washers. I tried to throw the ball and hit the side of the magnet. Well. After some failures. No! Are you kidding me? No.-No.-he bounced and got stuck. He should have looked more like this.

Another thing you can do if you have a strong magnet is to get ferrofluid liquid. The ferrofluid contains nanoscale chunks of magnetite, which is an iron-containing mineral, and they are suspended in a solution encoded in surfactants so that they do not clump. But in an external magnetic field, they all line up like iron filings around a bar magnet. This ferrofluid fluid began to develop parallel ridges even meters away from the magnet. And as we got closer, spikes formed on the surface, aligning the magnetite particles with the field. Closer still and the ferrofluid fluid climbed up the side of the container. - So it's not much, but it's kind of. - A little tug? - Yes, and then try tilting it outwards and then you will feel the difference. - Oh yeah.

He definitely wants to come here preferably. Magnetite is actually the mineral that led people to discover the phenomenon of magnetism in the first place. At least 3,000 years ago, naturally magnetized chunks of magnetite were found in a part of Greece called Magnesia. That's where the word magnet comes from. In Greek, they were called magnesia stones, but they were also known as magnets. And it was discovered that lodestones could attract each other or pieces of iron. And in the 11th century, in China, it was discovered that magnets could be used to make a compass needle that would always point in the same direction.

The side that pointed north of the Earth was called the north seeking pole. And on the other side, the south that seeks the pole. Although nowadays we usually simply say north pole and south pole of the magnet. But why are only some materials magnetic? Electrons are essentially small magnets, but in most atoms they are paired, one pointing in one direction and the other in the opposite direction. Then their fields are cancelled. In elements with half-filled outer electron shells, well, then they can't pair. So atoms have magnetic fields. But if the neighboring atoms are not aligned, then the magnetic fields of all the atoms cancel out and the bulk material is not magnetic.

But even if all of these atoms line up in one part of the material, known as a domain, they can line up in front of atoms in other domains and cancel out. So you need all the domains to be aligned. Normally when you see them, they are very strong magnets. But not here and not yet. And this can be done by applying a strong external magnetic field. Right now, these are not magnetic. They don't stick to each other. But he's loading them there, on the Helmholtz coil. - Do you see the machine here? - Oh! And then you get a permanent magnet.

Materials that meet these criteria are called ferromagnetic. After iron, the most common magnetic element. But nickel and cobalt are also ferromagnetic. In the powerful magnetic field surrounding the

world

's strongest magnet, what is even more surprising to see is the behavior of non-ferromagnetic materials. Here we have four sheets of different materials. Two different types of plastic, copper and aluminum. When they are stationary in the field, there is no difference between them. But when they move. - Two, one, let go! - Materials that conduct electricity fall much more slowly. (soft, happy music) I'll talk about that. But first, this part of the video was sponsored by Google and they were interested in this video because it's about magnets, which are critical to our future.

Electric vehicles, for example, use electric motors, which need magnets to operate. And search interest for electric vehicles in the United States reached an all-time high in the last 12 months. That is, according to Google Trends, a tool that allows you to see what people are searching for. What connects these trend searches and many others is that people are trying to find ways to do things that are less destructive to the planet. And Google says, "We live on this planet too. We want to do that too." In fact, Google has matched 100% of their electricity use with renewable energy since 2017.

They also run the Solar Roof Project, which helps people decide if solar energy is right for their home by providing Google Maps data to Create a 3D model of your roof and estimate energy savings thanks to rooftop solar. Personally, I'm glad to know that people are searching for things related to sustainability and that Google has also made a real commitment to sustainability. You can learn more about sustainability and Google's efforts at sustainability.google. Thanks to Google for sponsoring that part of my video. And now, back to the magnets. What happens is, as the metal plate falls through the field, the number of magnetic field lines passing through it changes.

This change in magnetic flux induces electrical currents, called eddy currents in the plate, which create its own magnetic field that opposes the change in flux. This is known as Lenz's Law. So if the plate falls towards a magnetic north pole, the induced currents create a magnetic north pole themselves, so the plate is repelled and falls much more slowly. So when that big plate falls, eddy currents are generated in the metal, which should dissipate some energy as heat. So I want to see if we can see that. - In fact, it is now slowing down. Because it is in a much higher field.

It's slight now, but I think you can see the plate getting a little hot as it falls. I previously visited an electromagnetic levitator at the Palace of Discovery in Paris. Oh! It uses an alternating current to levitate a plate, but the eddy currents in that plate generate so much heat that water boils on its surface. Look how hot this dish is. I like to think of Lenz's Law as the Law of "No, don't do it" because no matter what you try to do, nature works against you. - There you go. - Oh! If the plate falls, eddy currents are induced to slow its dissent.

Look at it! (laughs) But if you try to pick up the plate. (laughs) Come on! Nature also says: "No, it is not like that." In this case, a south magnetic pole is induced beneath the plate, attracting it back to the magnet. They don't know if I'm weak or if this is really incredibly difficult. Ah ah. Oh. - There you go. - Oh my God. - You are strong like a bull. - Oh. No matter how hard I tried to push the plate down, it just wasn't going very fast. Because even if you could speed it up a little, that would increase the rate of change of the flux and therefore the induced currents and their associated magnetic field.

That's ridiculous. It's so weird. We tried other conductive, but non-magnetic, objects around the magnet, like this thick aluminum cylinder. Drop it directly on the magnet and nature will say, "No, you don't." Try rolling it over the top. No, you don't. It just refuses to roll. We wrapped a volleyball in aluminum foil and put it over the magnet. Or drop it directly. Once again, the change in magnetic flux induces eddy currents that produce their own magnetic field to oppose the original change in flux. We wanted to see how much deceleration the 45 Tesla magnet's marginal field could achieve.

So we decided to shoot shells from a potato cannon overhead. - Are you ready? - Okay, we're ready. - Three, two, one. (metallic sounds) Heads! (metallic noises) - This is what the projectile looked like without the magnetic field. And this is what it looked like with the magnetic field activated. If we compare the two shots, it can be seen that when the projectile enters the magnetic field, the induced eddy currents spin the projectile. Therefore, it remains oriented along the magnetic field lines. And this minimizes the change in flow that the projectile experiences. - Three, two, one. - Now, some of the projectiles contained coils of wire that were connected to LEDs. - So the LEDs are actually polarized in opposite polarity.

So no matter which direction the field comes from, one of them will be illuminated. And we hope that when you cross a field, you'll see the nose cone LED's color change. - Mar And sure enough, these projectiles light up, showing how the induced currents are changing in the coil. (soft music) You know, in all these cases the induced electrical energy is dissipated, either in the form of light or heat. But what would happen if you had a material that did not dissipate energy, such as a superconductor below its critical temperature? There are two important things we need to know about the high temperature superconductor we are using here.

First, below its critical temperature, most of the material has zero electrical resistance, meaning that if a magnet is brought close to it, currents will be induced to oppose the change in flux. And since it is a superconductor, those currents can persist indefinitely and expel the entire magnetic field. Second, there are some filaments through the material that are not superconducting. - There are designed defects in superconductors, a second phase that trapsthose magnetic field lines and prevents them from moving. It can no longer go up or down because it is trapped in that magnetic configuration. - This is the human levitator.

It consists of a 40 kilogram or 90 pound magnet that floats on a ring of superconductors. So I'm standing in front of the magnet and underneath is the superconductor? - That's how it is. - When I stand on the magnet, it is pressed towards the superconductors. But the increase in magnetic flux opposes the currents in the superconductors which create a magnetic field that repels the magnetic field of the magnet I am standing on. Maintain my angular momentum. Oh yeah. So I keep levitating over superconductors. - I also brought a leaf blower, if you want to keep it, turn it on. - TRUE? (the group laughs) - It's up to you. - Let's get it. (Leaf blower hums) Now, there is another way to levitate in a magnetic field that has nothing to do with induced eddy currents.

And it's all becauseIn reality, all materials have magnetic properties. They are simply difficult to see unless a strong magnetic field is present. Some materials are always attracted to magnetic fields. They show what is called paramagnetism. Oxygen is like that. - We have liquid oxygen dripping from the bottom here and it's attracted to the magnet. No matter whether it is a north or south magnetic pole, the presence of the external field causes the material's magnetic field to strengthen the overall magnetic field. And that causes attraction. Other materials, in fact, most materials are repelled by a sufficiently strong magnetic field, whether to the north or south.

And this is known as diamagnetism. Water is a good example of this. In the presence of the external field, water molecules effectively become opposing magnets. And that's why they are repelled. Here you can see how bringing a magnet close to the surface of the water creates a mark. You can use this repulsion in a magnetic field strong enough to levitate objects you wouldn't normally consider magnetic. Here we are using a slightly weaker 31 Tesla magnet so we can use a periscope setup to actually see inside the hole. And our camera is there. - So as soon as you are on this optical path, you should be able to drop everything. - Marvelous.

This bur will be magnetic in a strong enough field. - Well, right now it's diamagnetic. It's just that we are not in a strong enough field. - Good. - Yes. - So we can see anything. - Mmmm. Correct. For the water. - Good. - Water is diamagnetic and there is a lot of water in strawberries. - Oh that's nice. Oh, that's beautiful. Yes, it's beautiful. And the same goes for a raspberry or a little piece of plastic pizza. Living organisms contain enough water to levitate. They wouldn't do it here in the magnetic lab, but people have levitated frogs. - Oh! - Yes, this is it!

Yes, there you have it. - No way! - And the grasshoppers? Even mice in experiments were intended to help understand the effects of weightlessness without having to go to space. So, are very strong magnetic fields safe for living things? - There are no lasting effects, there are no long-term effects. But we have noticed that there is the possibility of actually polarizing the stones that are in the inner ear. And the effect that that has on the rodent is that the rodent actually spins. - As if they were going around in circles? - They go in circles.

It doesn't last long. Only a few minutes have passed since the animal leaves the magnet. - So how do you actually make the world's strongest magnet? Contrary to what I expected, it is not possible to do this with superconducting magnets alone. - The highest magnetic field that could be generated with a superconducting wire was nominally 20 Tesla. - That's because superconductors have a limit to the amount of magnetic field they can withstand before they stop being superconductors. So the solution is to combine an external superconducting electromagnet with an internal electromagnet made of ordinary wire. - So, the blue, green and salmon colored bits, that's the superconducting exterior.

That produces 11.5 Tesla. Inside that, we put a resistive magnet that produces 33 and a half Tesla. Maxwell's equations, adding the fields, we obtain 45 Tesla. - But making high field magnets with ordinary resistive wire is really difficult. - For a wire-wound magnet, such as a scrap metal magnet, a traditional electromagnet, the highest magnetic field you can get is about two Tesla. And the reason is that you can't get the heat out of the innermost windings. Then, back in the 1950s, Francis Bitter at MIT realized that physics doesn't care what shape the conductor is. You can take the round wire and flatten it into a very thin plate.

If you then stack those plates with alternating insulators, you will form a helix that electrically looks like this. But now I can push the cooling water axially through the conductor stack. That means I can now extract all that heat from the innermost part, which means I can achieve much, much, much, much higher currents through these coils, up to 57,000 amps, than what can be done with a round traditional wire. electromagnet. - And that gives you 34 Tesla, that? - That gives you 33.5, but it is accumulated. So we stacked them all in a stacking template. They are lined with braces.

Then we apply about 20 tons of force to it and then we lock those tie rods and that holds the coil together and gives us our electrical connection between each turn. And we're pushing, you know, several thousand gallons per minute of deionized water through those coils to keep them cold because otherwise it melts and that's it. Occasionally, a material failure occurs which occurs when the material exceeds its plastic limit and begins to flex toward the coil next to it or perhaps even short to ground. And this is what happened here. The coil failed plastically, meaning the metal went beyond its elastic characteristics, where it would return, and simply deformed completely, which pushed it into the coil next to it, burned the insulator, and then vaporized all this metal.

And you can see more inside. It killed this coil, which is coil B. But because it failed on the inside edge, it killed coil A. It failed on the outside edge and also killed coil C. So it was a costly failure. - Costly failure. - Yes. Yes. The record is the highest continuous magnetic field in the world, period. China recently ordered its 45 Tesla hybrid, very similar in concept to ours. So now there are two of them in the world. - Running the strongest magnets on the planet requires a lot of energy. The Mag Lab uses a significant fraction of Tallahassee's electricity. - Thus we can consume around 8% of its total generation capacity with the four power supplies at full capacity. - What is the electricity budget for this place? - So, between 250 and 300,000 nominal dollars per month. - Holy, yes, that's a lot. - Yes.

That's why we operate on its mandatory federal reserve, which every public service company must have. They have to have that available to get on the network if there's a problem. We have reached an agreement with the city so that they can make money from the energy they have to produce, but cannot sell. The flip side is that when they need it, we get down and we can get down much faster than they can spin a Genny. - Why do you need 45 Tesla? - There are a couple of things that drive materials discovery. One of them is simply growing new material.

The other is to put it in an extreme environment, such as high magnetic field, high electric field, high pressure, ultra-low temperature. - Low temperature. - Another axis is to take an existing material and improve its cleanliness. Thus removing all the impurities. So by dropping the impurities into the material, you narrow down where the electrons scatter from there. And that improves the properties, it allows you to see things that you could never see before. We've barely scratched the surface of what can be done with this. People will look back in about 25 years and this will be the turning point, this five-year period.