The Most Powerful Continuous Magnets Yet Made

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Although many people don't give magnets a second thought other than their use to hold photos to the fridge door they are an integral and indispensable part of our modern life and without them we wouldn't have electricity and many other things. So inspired by a stint in an MRI machine I thought I'd look at the most powerful Continuous magnets yet made.
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Written, Researched and Presented by Paul Shillito
Images and Footage : iterorganization, UniServeScienceVIDEO, Fabio Battarra, Khan Academy India - English, SILVER SWAN, Make Toys, Racing Garage TV, practiCalfMRI, Philips Healthcare, MIT, MIT Plasma Science and Fusion Center
And as always a big thank you also goes out to all our Patreons :-)
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[@Daniel_Borisov]

I was genuinely happy to see you back Paul! Hope you are well.

[@cozdod019]

@8-Bit Andy the best reply to a youtube bot ive seen in the internet

[@guff9567]

"genuinely"? I don't that

[@lordgarion514]

@8-Bit Andy Maybe that's because they didn't do it in a year. The main part of the vaccine had been worked on for about 5 decades. (In fact, the first RNA drug was only patented in 2018) Now that that part was finished, the rest is typically pretty quick and easy, also thanks to many decades of research. Considering what you obviously don't know, I'm not taking your idiotic claims of man-made seriously either. Hint, pandemics and epidemics are very common.

[@hamstsorkxxor]

@@lordgarion514 I also like how, according to these conspiracy theories, covid-19 is simultaneously a man made bio weapon from china, but also completely harmless and all countermeasures are evil schemes by [insert random]...

[@IARRCSim]

@@hamstsorkxxor also simultaneously, some of them are happier to get infected with the Chinese bioweapon than an American-made vaccine.

[@CapsicumSpec]

CD is one of only a handful channels that have not lost their identity over the last years and still pleases us with absolute top notch content! Thanks Paul!!!

[@sunnyjim1355]

lol, look wider.

[@_DinoREX_]

One of the best channels I am subscribed to.

[@palealien]

You saved me the chore of writing a comment of equal emotion. X10.

[@JTA1961]

@@caramia6681 hit that right on the button...

[@awesomeferret]

Aside from all of the channels (like mine) where the identity isn't lost because we were too foolish to change to something better. Sometimes change is good.

[@psyclops973]

I really appreciate this guy's ability to explain highly complex concepts in layman's terms and interconnect all those concepts in a concise, yet really complete presentation.

[@02markcal]

I agree Paul has a gift to help the average person understand something that is complex.

[@toddsmith8608]

I was wondering if Homer Simpson could operate the reactor, then Paul said it's shaped like a giant donut. Mmmm... donuts.

[@simonreij6668]

couldn't say it better, love him

[@guff9567]

Pity about that last episode on prostate glands. That was REALLY off-putting

[@simonreij6668]

@@guff9567 you dark little dog xo

[@Matth3wM16]

Slight correction at 7:39, MRI machines operate on the basis of aligning spinning Hydrogen nuclei, not hydrogen electrons. There is a research area called EPR (Electron Paramagnetic Resonance) which does look at the spin of electrons in different materials.

[@robertlapointe4093]

Yes. The proper name for this technique is nuclear magnetic resonance imaging, where nuclear refers to the hydrogen nuclei (protons). When placed in a magnetic field the proton's magnetic moment (spin) can align with or against the applied field, resulting in two slightly different energy levels. The transition between levels requires photons in the radio frequency range, depending on the magnetic field strength. Nuclear magnetic resonance (NMR) spectroscopy is also used with other nuclei, such as carbon-13, fluorine-19, and phosphorus-31 (which, like protons, all have spin 1/2) and is used routinely for chemical analysis. NMR spectroscopy can also be used on higher spin nuclei, such as hydrogen-2 (aka deuterium, spin 1), but is more complex. The word "nuclear" was dropped from the name to prevent scaring the ignorant.

[@Forefatherrabbi]

There was on other point in the MRI portion that needed clarification. If metal is brought into the room while the MRI is at field, it will be pulled by the magnet, but they will not heat up because of the magnetic field. Metals heat up because of the RF (radio frequencies) being used to capture the image. The point still stands, Bringing metal into an MRI is very dangerous. As the video shows, small metal items can become projectiles (like that stapler). In the case of larger objects, they can cause people to become pinned and crushed. MRIs come with a "quench button" that causes the liquid helium to vent. Allowing the gradient coils to heat up means they will no longer be superconductors. And when the energy stored in the coil transforms into heat through resistance, the magnetic field is gone. You really don't want to do this, cause it can be over $100,000 to replace the lost helium and bring the MRI back to field.

[@captsorghum]

I forgot to remove my belt before getting an MRI once. The buckle vibrated at the same frequency as the buzzing sound you hear when the unit is operating. Possibly the most fun anyone ever had in an MRI machine.

[@thetruthwillout9094]

👏👏👏👏. Wow, you are all so clever.

[@RiftArgentEviany]

@@thetruthwillout9094 It's always so nice when people feel belittled by others having knowledge.

[@NekoWinters]

I swear to GAWD the quality of these videos is BETTER than any major cable network and the content is a hundred times more entertaining 🤩

[@Freemouse159]

What is a cable network?

[@sparkyfister]

@@Freemouse159 all of them combined!

[@dumoulin11]

Totally agree.

[@pantherplatform]

Touchè

[@02markcal]

... and if you are never curious, Paul's shirts are BETTER than any on the major cable network in my opinion.

[@RtB68]

It's a sign of how well respected this man is by his subscribers that when he makes an occasional content error, the correction in the comments is both courteous and constructive, rather than the hate-rant you see almost everywhere else. Great content Paul and a big shout-out to this wonderful community you've built.

[@LoftBits]

I like to think that Paul's channel doesn't attract riff-raff.

[@ddopson]

At 10:30, the failure mode for fission reactors is mis-construed as exponential runaway, and this is true for Chernobyl, and the lesser known SL-10 incident, but isn't generally seen as a risk for normal reactor designs. The more common risk is the challenge of dealing with the decay heat that continues to be produced long after the fission chain reaction stops -- this is is what caused the Fukushima and Three Mile Island accidents, and it's what most of the safety efforts focus on. All fission had ceased hours prior the Fukushima core melting down from decay heat.

[@BBBrasil]

Too true!! People think nuclear bomb explosion. This doesn't help to understand and address the problems and solutions of nuclear power. The design of the power plants is the problem to be addressed, once the problem of chain reaction is well known and solved.

[@Karagoth444]

Was about to post the same thing. The Fukushima reactor had arrested all fission activity long before the wave hit, when the control rods were inserted due to the earthquake. The decay heat of a large reactor is no joke.

[@Ebin_RDAK]

Would've been nicer too if CD had mentioned thorium based reactors, a technology that isn't as widely used but still quite very interesting that needs to be further developed, those don't solely rely on uranium, only a small amount in combination with the thorium element (which is much more abundant). With the added bonus that in case things do go south (be it a technical or human error) you can separate the two elements and easily prevent a meltdown iirc Edit: If I recall, you can't weaponize thorium either like we can with depleted uranium

[@lamaahruloma4270]

The post-reaction heat is like magmatic heat in the principle of having the same source of energy, but where are the differences? How rich is the Earth's inner anatomy in the isotopes of Thorium and Uranium? How is it possible, that despite quick decay isn't for example Neptunium somewhere present in the nature? And same with Pu, Am and above? Why it doesn't exist in dying or borning stars for example? What about dead stars and planets around them? I don't exactly mean Neutron or Quark Stars or beyond object, but stars in a state of birth or death or things like White Dwarfs.

[@gibbeldon]

A meltdown is a runnaway chain reaction that cannot be stopped because it became impossible to absorb the neutrons causing it. This progress generates a lot of heat and melts the cores down, hence "meltdown". That is a serious problem as it will continue to generate radioactivity without any way of stopping it, whilst melting the ground and therefore threatening to contaminate ground water. If it doesn't explode it's because critical mass isn't achieved, so it won't be exponential. That doesn't mean there is no more fission going on though.

[@forrestmorrisey]

As someone who works on MRI Machines, it never stops blowing my mind when you think about the science behind it.

[@therealb888]

This makes me curious. By work on MRI machines what kind of work do you do? Could you be more specific please?

[@philipmcdonagh1094]

It will be a while before i can pick up a handheld one in the shops.

[@CitroenDS23]

It is all magic to me. Clang clang clang, here is your future scribed on a sheet of plastic. (

[@carlstanland5333]

I’ve been repelled by magnetism videos in the past, but this one really attracted me.

[@troywalker8078]

Boooooo

[@mgx9383]

Because now you're facing Paul S.

[@DavidOfWhitehills]

Oh for flux sake

[@kitemanmusic]

Is this why some women are fitted with the coil?

[@cyborgar15]

yuck..

[@UnknownUzer]

I had no idea that they had come so far in fusion research. As a child of the 70s/80s we were taught that it was a goal to one day use fusion to power our civilization, but they also cautioned that achieving this goal was just below achieving faster than light travel in odds of it actually happening. I love seeing the science fiction of my youth become the scientific reality of today's youth. On a side note, I want to thank you for always explaining things in a fashion that is neither condescending to the viewer , nor so unnecessarily complex in lexicon that the viewer (me) has their eyes glaze over and give up on trying to learn something new for the day. Your approach to educating via layman friendly language and tone, makes it SO easy to not only understand the topics you cover, but it also makes it easy to relate one's life, and immediate world, to the topic at hand. I am very grateful that you chose to share your passion for science with me, and I am very happy that your recent personal challenges have not dampened your desire to learn and to share what you learn with the rest of us. I, for one, would greatly miss your calm , soothing, tone walking me through another chapter of human achievement. God speed, kind Sir.

[@cornoc]

come very far, but note that the total energy cost of running ITER will be something like 550 megawatts and even with an unrealistic thermal efficiency of 50%, the reactor facility as a whole would only be about half-way to break even. but with improvements in high temperature superconductors and other research who knows what the future might hold.

[@xyzpdq1122]

Practical nuclear fusion has been 25 years away for over 50 years.

[@Automobiliana]

Very well put

[@cornoc]

@@xyzpdq1122 i think this is a failure of people not being pessimistic enough with their timelines rather than the impossibility of the task

[@kurtpena5462]

As far as we have come, we are no where near being able to realize sustained fusion power gain. Any system that generate power on this basis will pose hazards akin to any other high dollar large scale engineered system, like a hydro-electric power plant, nuclear fission power plant, space ship, or commercial airliner. I'll take a warehouse full of RAM in the desert over airborne hydrocarbons any day.

[@joelado]

Paul Shillito your particular genius is your ability to explain complex things in an attainable way. I now understand what fusion is all about. Thank you.

[@brianmessemer2973]

Agreed, Joe. Paul is a master teacher.

[@davidashmore3929]

Thank you Paul. Hope you're feeling better.

[@carbon_no6]

I’m always amazed by magnets. Not having personally handled a magnet with extremely large pulling power, but to see something either repel from one or attract to another when there is no “visible” processes happening is insane.

[@Erik_Swiger]

So, he says magnetism is caused by the movement of electrons in matter, so, a permanent magnet is a magnet that somehow has a perpetual current in it, which would seem to be impossible, or more likely, I just don't understand something. But Gawd it's so fascinating.

[@SimonWoodburyForget]

Gravity does this in a fairly similar fashion, even if "negative gravity" isn't known to exist, you'd talk about electromagnetic fields in a similar fashion as you'd talk about gravity, by talking about spacetime as a field of vectors. This is because EM and gravity are fundamental forces, meaning they have no (known) mechanism of action, so you can't really talk about them like you'd talk about air in fluid dynamics. The other noticible difference is that gravity is a weak force while electromagnetism is a strong force. I mean this is kind of and understatement, because gravity is extremely weak, to the point of barely being measurable without specialized equipement. You typically imagine gravity working at the scale of planets, but electromagnetism also works at this scale. You can actually find entire nebulas polarizing light due to their aligned magnetic fields, which essentially acts as giant magnet in space, but you can't really find gravity affecting much at the smaller scale.

[@SimonWoodburyForget]

​@@Erik_Swiger Technically not exactly how it works, but it's a very good analogy. Technically speaking, the electromagnetic field around a copper wire transmits the energy, and not the movements of the electrons. A material has the ability to "transmit current" if the material itself has a negative/positive charge. This is sometimes described physically as a material having a few spare/lacking electrons. The electromagnetic field of the magnet interacting with the copper's is quite literally what allows it to produce energy. That's how you can make sense of magnets producing energy when moved in relation to a copper wire. The energy is transmitted quite literally into the electromagnetic field of the copper. The way you actually get energy out of a magnet is by moving it or it's electromagnetic field. This is to say you'd want to think about it like an invisible chain moving through the wire being the current, only producing energy as it's moving, so long as you don't think too hard about it, because alternating current actually produces power by alternating into either directions.

[@jovetj]

​@@Erik_Swiger A magnetic field doesn't automatically mean electric current. The circumstances have to be right. That topic is called _induction_ and can lead you to some fascinating reading for sure.

[@jovetj]

The really wild thing about magnetic fields is they're actualized by photons, just like light is.

[@clarencegreen3071]

This video is a masterpiece in which "volumes" of information are presented in a logical and coherent manner that builds from basic concepts to the fusion reactor. Very well done, Sir!

[@pantherplatform]

Touchè

[@mikeclifton7778]

Those figures are absolutely mind bending, though 15 times hotter than the centre of the sun is how my daughter in law has the heating on at home! Great to see you looking so well, long may it continue and thanks for the superb content.

[@josephstevens9888]

LOL!

[@thewiirocks]

It's also a clue as to why the sun works and fusion here on Earth doesn't. (At least not sustainably.) It turns out that our sun isn't large enough to produce nuclear fusion through pressure and temperature. Thanks to its density and size, random quantum tunneling events cause particles to "accidentally" end up in the nuclei of other atoms, resulting in a fusion event. Such events are very rare, but with something as large as the sun, they happen often enough to keep the nuclear furnace running.

[@cornoc]

@@thewiirocks that same tunneling mechanism is a giant proportion of the fusion events in any star, regardless of size, is it not?

[@thewiirocks]

@@cornoc It's going to play a big part, but the effect slowly gets overshadowed as stars get larger. Once the mass of the star is great enough, "normal" fusion events from pressure and temperature begin to take place. Which is why the larger the star is, the hotter it is and the faster it burns through its fuel. A typical blue giant, for example, lasts about 1/100 the time of a yellow star like our sun.

[@cornoc]

@@thewiirocks hmm interesting. i guess at a certain point the nuclei just have enough energy to overcome the potential of the electromagnetic field, and so tunneling will still increase the number of reaction events but is no longer necessary for them?

[@homo-sapiens-dubium]

Just wanted to say that its a great a idea to frequently mention your cancer story in your videos, just to remind people to GET CHECKED and talk with their relatives about this topic. As someone having a similar case in my family, I didnt know how to handle it in this regard, but spreading the message that it hits anyone eventually is essential. GET CHECKED IF YOURE OVER 50, for prostate / breast, colon cancer, at least! should be free in most countries!

[@Leonelf0]

Also regularly check your breasts and/or testes for lumps or painful spots. Both types of cancer can easily be spotted and have a good outcome when treated early. Especially testicular cancer affects young men, so when wanking all the time one might as well check two inches further down

[@guff9567]

DISGUSTING

[@guff9567]

@@Leonelf0 Stop being revolting

[@BOT_0x76DE45AB]

Should be free in most countries? Really?

[@homo-sapiens-dubium]

@@BOT_0x76DE45AB at least covered by healthcare. Its cheaper to find and remove a tiny bump than fight stage 4 cancer, tell your aunts and uncles about it. Colon polyps are found regularly, if not removed they develop to cancer, happened to my dad... They should ask their doctors about this / ask for checkup! Cheers!

[@kiggi__]

good to see you back with a fantastic video.

[@koharaisevo3666]

14:43 Note that the 500 MW heat release need to be converted into electricity with an otimistic efficiency of around 50% so the power comes out is only 250 MW.

[@cornoc]

and true cost of running the entire facility is more like 550 MW... still, big progress

[@kerbodynamicx472]

At least the Q factor is about 10. For a fusion reactor as a power plant to be commercially competitive it has to reach around 50. Still, big progress

[@kindlin]

It will about break even, as I saw some numbers quoted. So, with research completed at ITER and other facilities, the next generation should be on the grid and producing power. I don't believe any of the dream fusion reactions will be on the grid before 2030, maybe 2035 at a smaller scale.

[@kerbodynamicx472]

@@kindlin I will put commercialised fusion somewhere around 2050, and becoming a major source of energy by 2100.

[@kindlin]

@@kerbodynamicx472 I'm only saying that by 2035, 2040 at the latest, there will be some device using fusion power powering a community, a city, a moon base, somewhere, in a commercially viable way.

[@rayoflight62]

The best-explained video on fusion on YT. You outclass them all. One thing worth mentioning, beside the problem of energy balance, Qt Vs Qp (total efficiency Vs plasma efficiency), is the problem of the tritium portion of the fuel. If we have to feed all that tritium into the plasma daily, we can't... There isn't enough around. The agreed solution comes from the tritium for fueling can be breed by irradiating the deuterium with neutrons. ITER contains a converting blanket to test the viability of the breeding method. If this doesn't work as expected, it could be a big headache for reactors using a Deuterium-Tritium mixture as fuel. This is the mixture that require the lowest temperature for ignition...

[@TheAnonymous1one]

You have such a magnetic personality. Love droid videos

[@Insanitypants80]

It's a great video, but before we get too excited, I remember reading an article in New Scientist in the 1980's about JET and how fusion was about to go energy positive. It's one of those technologies that seems to be forever just round the corner.

[@Goreuncle]

@@thewafflehouse841 I doubt it.

[@incognitotorpedo42]

It doesn't matter. Fusion will NEVER be able to compete with existing renewables+storage. You want to pay a buck a kWh? Great, go with fusion. After we squander billions more Euros on the fusion scam and finally have a working plant, then what? Why, the taxpayer will be asked to subsidize it! Fusion will never make it on its own. It's a complete waste of money, time, and brainpower.

[@ethanbottomley-mason8447]

@@incognitotorpedo42 The difference between fusion and renewablesis that we are clode to the maximal efficiency of renewables. With fusion, we are nowhere near the limit of output power. Long term, fusion will be significantly more effective.

[@ghoulbuster1]

40 years ago it was all on paper, now we have real reactors working. We just need efficient magnets and a good spark from a pellet.

[@57thorns]

@@incognitotorpedo42 A US dollar a kWh? That sounds about right in an all-wind/solar/storage electricity network. At least when you need the electricity the most, in cold, still, winter nights.

[@psygn0sis]

I genuinely get excited when I see a Curious Droid video pop up in my sub feed.

[@gabedarrett1301]

Remember that your work doesn't go unappreciated! Thanks for everything!

[@moos5221]

Man, I will never get tired of hearing about Fusion Reactors. It's so fascinating!

[@naciremasti]

We're all pulling for you to get thru this Paul. You're a goddamn inspiration. Keep it up.

[@je6874]

I must’ve missed something, what happened to him?

[@naciremasti]

@@je6874 kzbin.info/www/bejne/mKKqkmuPa6iLn7s

[@texastaterbug5395]

I love your channel! As a Diagnostic Radiologist, I have to say that your description of the safety hazards of MR Imaging is almost perfect. However, we do now have many patients with implanted devices getting imaged in our scanners. The devices and scanners can often be programmed to allow for safe acquisition of helpful diagnostic images.

[@SeanCMonahan]

I have a titanium plate (volar with screws) for a distal radius fracture. I found it fascinating that even though titanium is MRI safe, it does interfere with imaging the area. I had a suspected TFCC lesion from the same incident - the airbag went off while I had my hand on the horn - and the plate made the MRI nearly unusable. It looked like a spooky ghost haunting my wrist haha. This was with having put me into a machine with a weaker magnet for a longer imaging session, trying to compensate for the nearby plate. Anyway, radiology is super interesting!

[@nigelrg1]

Curious Droid is absolutely my favorite channel for scientific topics. It's calm, matter-of-fact and extremely informative.

[@ridermak4111]

Once again, Paul proves me wrong. I never thought I would even begin to understand these concepts. Paul’s presentations are amazing. 👊😎

[@kerbodynamicx472]

Believe in yourself, if you are watching this channel, you are probably a smart fella

[@numbersguy6099]

Paul - thank you for this - excellent content as usual. Two points to bring to your attention for future videos: one of the special metals you mentioned is neodymium - you pronounced it "neodynium"; and Johann Carl Friedrich Gauss has the "a" before the "u" in his surname - your graphics had them the other way round. On a personal note, I, too had an MRI scan last year - a quite amazing experience. I knew the basics of what was happening around me, but your explanation and description showed me hat it is much more complicated than I imangined.

[@leeroy25024941]

And you missed a T in the word THAT on your last line....My point being its a very minor error, and isn't really going to change the understanding of the video content.

[@michealoflaherty1265]

I'll definitely show that explanation of magnetism to my students. Best I've seen yet. Welcome back Paul.

[@SinclairA]

After 30 years I finally understood magnetism. Thank you!

[@campsitesweden]

Never heard anyone on yt or anywhere else explain complicated matters in such an understandable way. Subscribed.

[@petrilaakso7927]

I’ve watched your videos every time but never said: Thank you 🙏🏼

[@NANDOFFDataRecovery]

Excellent video as always. Many thanks

[@freakshow1997]

a small comment on the fusion device: The fuel required to have the fusion work is so-called D-T, which means Deuterium and Tritium. Deuterium is isolated from regular water routinely, but Tritium is another matter entirely. This has to be made in a fission reactor (preferably) by irradiating lithium. Tritium is radioactive, with a halflife of around 12 years, and emits weak beta radiation. So it's not the case that we have "infinite" fuel at our disposal for fusion reactors. Also, whilst the plasma charged particles can indeed be manipulated wit magnetic fields, this is not the case for neutrons. They will fly all over the place, being uncharged. All in all, fusion does not seem to have the promise, and thorough investment in fission reactors is warranted.

[@waylontmccann]

Hey Paul, glad to see your feeling energetic enough to give us a video, and what a video! I keep my eye on the fusion space, and look for videos about the new fusion power projects being built. This video has explained more about the reported progress toward net positive fusion power, and what exactly needs to happen to obtain it than any other I've seen, and you've done it in a very straigt forward manner. 👍 great work!

[@TheMechanator]

He mentions a trip into a MRI machine. I hope he is ok, what malady or disease are they looking for? Cancer?

[@JohnMichaelson]

These are the kinds of things that as I advance into "Get off my lawn" years I regret knowing I won't likely be around long enough to see the full implementation of. But it's still neat to be at the early threshold of the attempts, though.

[@marcusambler4205]

Glad too see you back with another very interesting subject... Wishing you a speedy and full recovery.

[@sydclark5581]

Alot of info, but a clear and simple video made it an easy watch

[@syx3s]

i've asked myself this for a long time: how is it that one man can write, reasearch, and produce, a show that is better than any other channel on youtube? in my opinion no one even comes close regardless how big of a team they have. kudos paul, i wouldn't believe something like this was possible if you weren't doing it.

[@syx3s]

i especially love seeing topics about things that i already know a fair bit about because i know i'm going to learn even more interesting things in his videos. happens every time.

[@nitehawk86]

By making more infrequent excellent quality videos instead of shitting out a 5 minute reaction video every day. However, youtube penalizes channels like CD as they would rather have the constant stream of low quality videos.

[@prudencepineapple9448]

From memory, the first recorded death by hospital equipment was that of a boy undergoing a MRI. An oxygen tank was hurled into the machine and he was crushed by it. I recently had a scan by another hospital device that almost fully enclosed me. The sound was like a jackhammer right next to me. It went on for about 25 minutes. I don't know the name of it but it was very claustrophobic.

[@Forefatherrabbi]

Loud jackhammer noises, long scan times, and closed spaces totally sounds like some sort of MRI. If they asked you a bunch of questions about pacemakers, tattoos, jewelry, etc, it probably was some sort of Magnetic Imaging. Hope your scans came back OK.

[@volentimeh]

@@Forefatherrabbi magnetic ink in tattoos? I wonder who discovered that the hard way.

[@C-M-E]

I happened to work in a trauma center in the late 90s and early 2000s, and unfortunately have seen the aftermath of an oxygen tank going Through a doorway (as in forcefully, taking Out the door and frame), an operator's station and finally doing a Chop Suey on an MRI machine. It was caused by a vendor coming in through the ER doors after normal hours which happened to share a corridor with the MRI suite. Suffice it to say, a lot of hospital policies changed after that.

[@Forefatherrabbi]

@@volentimeh good question. Most people first notice inching, pulling or tugging sensations. When the scan is being performed, the radio ways hit the metal in the tattoo like an antenna and the energy has to go somewhere. So it goes into your tissues as heat. It will not instantly burn you, but will heat up the more RF it gets. Some people with small amounts of metal (like in a tattoo) can still receive a scan, but the RF needs to be dialed back and the scans spaced out so the metal has time to cool before it gets blasted again. Animals can get MRIs, and the microchips in pets is OK in the MRI and will not be broken or damaged, but it is something the veterinarian will look out for.

[@prudencepineapple9448]

@@Forefatherrabbi I have to tell the technicians I had an umbilical hernia that was fixed using a titanium mesh. But I think that's with the MRI. The other machine was even more claustrophobic. I was given a choice of music to listen to using headphones as the test would take 20-25 minutes. I couldn't hear the music though due to the jack-hammer noise.

[@billmcintyre3652]

The Thumbnail with a Mushroom Cloud of Iron Filings to represent the worlds most "Powerful" magnet is a brilliant touch!

[@alexandrudanciu7874]

This was the most genuine ,briliant ,original explanation from them all about how in real life Tokamak work. At this moment (march 2022)is the BEST video about fusion, on internet. Thanks for that sir.

[@agesteiro7326]

Good to see you back. Good recovery mate. Realy love you’r Chanel

[@awesomefacepalm]

I had no idea that the magnetic fields in a fusion reactor were so insane. That's mind blowing!

[@mickyr171]

Im more curious what would happen if a tie rod holding the top and bottom broke and the whole thing blew apart, at 150 million degrees im guessing the whole building would be incinerated along with all the workers long before the chunks of metal did damage

[@awesomefacepalm]

@@mickyr171 I don't think the plasma would be a big problem. It dissipates very quickly when the magnetic field stops from what I understand

[@mickyr171]

@@awesomefacepalm oh ok then, that's a good thing

[@Jehty21]

@@mickyr171 isn't the thermal mass way to little to cause that kind of damage? Yes, you have these crazy temperatures but only a really small amount of material (I believe it's just a few grams) is at that temperature.

[@platospotatoes6205]

@@gags730 Really it's the cost that makes me grimace... ITER as presented in the video takes in 300 MW to output 500 MW. Ish. For how many billions of dollars? It's frankly no use is the end product of fusion (unlimited input resources with no waste!) costs billions of dollars for a few hundred MW.

[@itsmoot2879]

come on mate, we need more of your greatness.

[@jh6031]

As usual, truly fascinating stuff, Paul. Glad to see you up and about and making such thought-provoking content.

[@02markcal]

I still remember the curiosity and wonder magnets gave me growing up while playing with them and the iron filings, it seemed magical. ~ Thanks, Paul.

[@pantherplatform]

Touchè

[@maximilianschmidt6708]

Great video but as a physicist I spin a little bit, whenever you are talking about "spinning electrons". Electrons do not Spin. They have a quantum mechanical property that is called spin. However that has nothing to do with the physical process of spinning. Electrons do not have a volume but are seen as point-masses. It is thus impossible for an electron to "spin" in the classical sense.

[@CheapCheerful]

Interesting, thank you.

[@kitemanmusic]

An interesting 'point' of you! (view)

[@bbrandonh]

Super well organized and explained, awesome

[@Bobby_Snoof]

Magnets have always captivated me since I was very young! It's such a huge subject, it's endless.

[@rustyfox81]

Wow excellent video, never knew the energy out was proportional to the magnetic field to the power 4 !

[@Exerkitus]

Great video, Paul! One point of interest: the interaction of neutrons with the coolant water (and moderator in LWRs) only heats it by a few percent of the total - the daughter nuclei from the fission contain the majority of the fission energy and it is their impact with the ceramic lattice of the fuel pellet that causes it to heat up. That's why the cooling of the fuel is so important - nuclear thermal hydraulicists wish that the heat was formed directly in the water, it would make life a lot simpler and would allow reactors to be even more efficient! In fusion reactions, however, the neutrons carry most of the energy (irradiating the vessel as you mentioned) so heat will be extracted by their deceleration in breeder blankets, producing fuel in the process. Cheers!

[@ethzero]

Very nicely done.

[@bikerchrisukk]

The best thing about this channel, is that you don't see thousands of 'filler' images and videos, only useful ones. Great work as always! 👌

[@JoeSavySC2]

Hope all is well.

[@gregbrookman]

This is one of my favourite videos of yours, Paul. I love that you got the idea from your own personal experience of being in an MRI machine!

[@MatyasLemberTutorials]

You have such a great ability to explain things simple. So easy to understand. Also great illustrations. Very well done, thank you for sharing!

[@MetalRenard]

Absolutely love your videos. Fascinating topics, really well presented. Thank you.

[@top6ear]

Pretty stunning technology.

[@bartomiejdurlej9665]

As always, awesome video

[@sixtorodriguez1902]

i love that fact that you keep the original intro into the episode that you are introducing, long life fan, keep it up you are a survivor

[@PovlKvols]

Great choice of subject, and as always excellently presented. Good to have you back!

[@burntnougat5341]

Good stuff as always but you forgot to mention one of the key principles of MRI which is precession of H atoms.

[@andydsm]

Absolutely fantastic video :) however after tons of material I've watched and read about fusion reactors (TOKAMAKs in general) I still cannot understand how will the heat from the plasma ring in a self contained liquid helium cooled tokamak, be "extracted" to heat water for steam turbines?

[@jimgraham6722]

The energy is conveyed from the plasma ring to the blanket (or heat jacket) by fast moving neutrons generated by the fusion reaction. The kinetic energy of the neutrons striking the jacket and their subsequent decay is the source of heat. The reactor can then be cooled in a similar manner to fission reactor (pressurised water, molten salt or high pressure gas) with the heat conveyed to Brayton cycle turbines. It may also be possible to extract energy from the plasma using magneto hydrodynamics but I am unsure whether this has progressed beyond a theoretical possibility.

[@andydsm]

@@jimgraham6722 Thank you so much for the explanation! To me this principle sounds more like a particle accelerator energy transfer, which is interesting :)

[@jimgraham6722]

@@andydsm My understanding is the durability of the heat jacket under intense neutron (as well as other radiation) bombardment is still bit of an unknown as so far the fusion reactions have only been of short duration. The net radiation flux in a fusion power reactor is expected to be about 100 times that in a comparable fission PWR so materials will get a lot of wear and tear, requiring regular replacement. Relining the reactor from time to time will undoubtedly be a big deal.

[@andydsm]

@@jimgraham6722 As I read your explanation to my 1st question, I also started thinking that even if in the following years we have a successful q over zero tokamak ignition for testing purposes (i.e ITER or another one), the next step of actually working on the energy transfer for actual useful work, would be a monumentally difficult task as well.

[@jimgraham6722]

@@andydsm Yes, it's a way off yet and the initial power plants likely to be very large and very expensive. Sabine Hossenfelder recently gave what I think is a reasonable summary of state of play. kzbin.info/www/bejne/gnuXiGSdYpt9n7s

[@ahmetcelalzirzakiran9986]

I am glad to see you again, as much as to see a friend of mine, whom I fear I will never see again Mr. Paul. God be with you !!!

[@romulusxyz6722]

I'm so happy to see you posting again Paul!

[@guff9567]

And continuing, WITH NO REPENTANCE, to shovel down packs of prostate-inducing: * red meat * processed meat * cooked well-done meat * dairy products * alcohol * saturated fats LOL

[@ArtOfficialKreations]

Glad to see u drop a new upload. :) (I hope I’m not being too much of a dik here by pointing this out, but @ 4:20 there are a pair of oopsie-daisy-typos..). It’s not necessarily necessary, but should you decide u want to make the corrections, the culprits are: _“Teslsa” & “Guass”_

[@escapedbits2732]

Nice content; I really enjoy those videos. But many continuous running NMR magnets far exceed the magnetic fields in tokamak fusion systems. For example, the University of Florence has a 28.2 T magnet system. Further, commercial NMR magnets are available with fields up to 23.5 T. (And I believe 45.5 T is the world record for a continuous high-temperature superconducting magnet, ref: Nature, "45.5-tesla direct-current magnetic field generated with a high-temperature superconducting magnet", 2019)

[@LaserFur]

I have a 1960's NMR with a 0.5T magnet. I have no idea what to do with it.

[@escapedbits2732]

​@@LaserFur That is awesome! One of the early days of NMR. Have you worked with that device?

[@LaserFur]

@@escapedbits2732 I got it from a university that said. "come bring a trailer we need to clean out this area". Unfortunately all the cables are cut and missing. so all I have is the books, rack with the amps, and the unit itself with it's chart recorder. It would take a lot of work to get it to work again.

[@patrickmertz2426]

Great video Paul, really enjoyed it and learnt new things. Hope you recovery is going well.

[@SteveWalkey]

Great info bud, well presented. Thanks!

[@Peter_S_]

I used to do consulting work for Toshiba MRI. Their magnet development building had a very large test area with bright yellow tape on the floor to mark an area that needed to be clear of anything. Before the yellow tape, they had a screwdriver fly into a magnet at extreme speed and impale it.

[@David-yo5ws]

Mmmm Hope they transitioned their tools to brass, copper, aluminium and plastic as an extra safety factor? Or did they just 'stick' with the yellow tape and pre-training courses?

[@Peter_S_]

@@David-yo5ws I just networked and repaired their Macintoshes. I stayed well clear of that area with my disks and portable hard disk.

[@David-yo5ws]

@@Peter_S_ LOL And especially the Floppy Disks ;-) Ahh those were the days of 8MB hard drives and bug ridden firmware 😱

[@Peter_S_]

@@David-yo5ws Yep, the floppy days. By that point I was using a ST-225 20MB for a portable drive and then upgraded to a Miniscribe 8425 which was also a 20, but in a 3.5 form factor. Super high tech!

[@flyingfree333]

There are several fission reactor designs that can't melt down and all fission reactors that have containment buildings can't harm people or the environment even if they could melt down. Fission nuclear reactors are the safest, cleanest, most reliable form of power generation we currently have.

[@winterwatson6811]

It’s hard for someone in their daily life to connect fossil fuels to the massive number of excess deaths that fossil fuels cause. It’s easy for them to understand Fukushima.

[@ironsides982]

Unfortunately, politicians are an unsable and dirty form of political power, and they decide the fate of our future electrical power development.

[@SimonWoodburyForget]

Incorrect: fission nuclear reactors are currently not a form of power generation. You'd have to first be able to generate more energy then you'd consume running the reactor alone, and only then you could call it a "form of power generation". There's potential, but we do absolutely not "currently have" it.

[@JasonPeterPresents]

Man your videos are so great. Straight to the point, no filler. Glad you do this.

[@magnumcipher4971]

Happy to see another one of your videos come through my feed. Another fine video my friend. Thank you.

[@MaxWindshear]

When the first fusion reactor is operating 24/7, I wonder how close you can get to it before electronics begin to fail. Will there be a huge area around the facility that's off limits?

[@MushookieMan]

Magnetic fields roughly follow an inverse cube law rather than an inverse square law, which is why you don't erase your hard drive by having a magnet in your screen to detect that the laptop lid is closed . And you can control where magnetic field lines go with metals and dielectrics.

[@SilvaDreams]

We already have functional fusion reactors.... Their only problem is they don't really produce a positive output, at best they can self sustain but what excess they can make is a joke at best.. You might run a watch off it if lucky

[@GoldSrc_]

There are metals that can shield magnetic fields, if you ever had or saw a CRT TV, those had magnetic shielded speakers for obvious reasons. CRT-based oscilloscopes use a Mu-metal shield. Mechanical hard drive magnets have Mu-metal plates that keep their stronger magnetic field away from the platters.

[@andrewolson248]

@@SilvaDreams Sooo...... you're saying there's a chance?

[@nerfinator03]

@@SilvaDreams actually its not even close since none of the power for the cryocoolers and auxiliary systems is calculated in those figures

[@jerrytugable]

Very interesting, thank you.

[@Matthew-ju3nk]

Always a fascinating show Paul. Glad to see you back up and running.

[@Dufftata]

best Explanation on fusion ive seen, thanks!

[@finlayfraser9952]

I must have missed something, we went from permanent magnets to fusion reactors. Are the solenoid magnets permanent?

[@kitemanmusic]

No, they aren't, but I don't understand the need for permanent magnets.

[@stephenbeauman6290]

Glad you're back fellow!

[@Gaus-bc6yx]

Love the video! It was really interessting and a relavant topic. Hope to see more soon and im glad youre back!

[@imc_6271]

What an excellent explanation of something I've often wondered about but never even started to understand until now. Thank you!

[@thedamnedatheist]

What happens if the fusion reactor's magnetic field loses power, even for a nano second? Wouldn't the plasma expand explosively, sublimating everything in it's vicinity?

[@cdl0]

ITER uses superconducting magnets, so no power is needed to sustain the magnetic field. The whole structure is extremely robust in order to contain the forces generated by the magnetic fields, heat, and pressure.

[@TheMechanator]

If the field of the superconducting magnets lost their power due to short or over temp, there would be a quench. boiling the cooling liquid and high resistance. The magnet would be permanently damaged. The plasma would leak from the magnetic mirror or bottle and hit the walls of the reactor chamber. The chamber in a modem commercial reactor would be lined with not only tungsten but lithium to drink in the neutrons and make tritium for fuel. Still, no, a hot mess it would be, but no runaway reaction and explosion of a nuclear sized yield, just an industrial accident of a costly machine.

[@Khempejjer]

Great video, as always. Hope you are doing well.

[@Sojourner-ql6du]

Great stuff. Thank you!

[@WarrenPeace007]

Love this channel. Thanks for all your hard work

[@trevorlam9638]

Love this channel. Have you done anything on molten salt reactors or LFTR type technologies? Would be a great episode!

[@backcorp]

Great

[@simon8864]

As usual, a very interesting and superbly delivered documentary. Thanks

[@ronjon7942]

Wow, what a show. Amazing. As usual. Paul, thank you. Nice work.

[@MrHichammohsen1]

Great video as usual. The Safire sun project already achieved fusion only with electric currents. The problem in fusion was always the physics not the machine.

[@TheEvilmooseofdoom]

Ah yes, the EU which claims much and delivers nothing.

[@adilsongoliveira]

No, it didn't: kzbin.info/www/bejne/rJ65lYOdoNqXeZo

[@cade8986]

As an MRI technologist, I love magnets.

[@Alex-cw3rz]

As a orbz enjoyer, I love magnets

[@NekoWinters]

As a furry I am magnets

[@02markcal]

The hard drive in my laptop computer loves magnets too.

[@Warekiwi]

Fascinating. Paul , Probably the best explanation of magnetism,, superconductors, and fusion I've seen yet! I'll definitely need to watch it a few times to take it all in !

[@frankgulla2335]

Paul, Thank you. Clearly, I have been slacking off and have not kept up with the latest in Fusion technology. Exciting time! Thanks for the great visuals and terrific graphics.

[@yagovips]

Hey hope you are okey

[@oldmandoinghighkicksonlyin1368]

I've been asking this question for a while but have not yet found a satisfactory answer: "How will a fusion reactor convert a hundred million degrees in temperature to electricity?" If it's just going to boil water to make steam to turn turbines, that seems pretty wasteful considering you only need 100 degrees Celsius to do that. Building many fission reactors for the price of one fusion reactor seems like a more efficient way to convert water to steam.

[@BRUXXUS]

Yep.... it's going to use the hilariously ancient form of steam power to drive turbines.

[@oldmandoinghighkicksonlyin1368]

​@@BRUXXUS All the artisinal craft beer hispters are putting on their top hots and twirling their mustaches all the way to the Steampunk convention when it's held in celebration of ITER being switched on.

[@BRUXXUS]

@@oldmandoinghighkicksonlyin1368 Hahahaha, I mean.... why not? But yeah, it still feels super weird that we're developing this ultra-high tech power source, but still just using it to boil water. While it's fairly efficient, I still feel like there's got to be better ways to get electrons moving.

[@borysnijinski331]

Steam at 100°C is only useful for making tea. Water is boiled into steam, the steam is heated and that heated steam drives the turbines. Steam at around 540°C is typically found in coal plants. About 270°C in nuclear plants.

[@oldmandoinghighkicksonlyin1368]

@@borysnijinski331 Still quite a deficit when fusion is cranking out a hundred million degrees Celsius. Seems wasteful.

[@paulpertzborn4797]

That ship lifting fact is just mind blowing

[@techtinkerin]

Wow that was a fascinating watch!! Great stuff 👍😎❤️

[@MaffiaRK]

Fucking magnets, how do they work