Tokyo researchers created the strongest controllable magnetic field in history | Hacker News Reader

Tokyo researchers created the strongest controllable magnetic field in history

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80 pointskulu200232 comments

Anti-clickbait: they didn't blow up their lab, just blew the doors off an iron enclosure intended to contain the massive shockwave, which turned out to be even more massive than intended. Still impressive though!

> just blew the doors off an iron enclosure intended to contain the massive magnetic field

Now, I'm by no means a physicists, but aren't iron enclosures particularly bad at containing magnetic fields?

It had a lot of holes, maybe that has something to do with it. Looked like a giant microwave door screen.

The magnetic field will tend to concentrate in the iron, meaning it shouldn't propagate as far.

Same as using Mu metal for magnetic shielding - https://en.wikipedia.org/wiki/Mu-metal

It shouldn't propagate, but the whole thing should be magnetized at that point, right? While you've got that electro magnet on you could probably stick fridge to the big iron magnet you've created with the container?

Depends on how the field moves relative to the iron. If it expands then contracts, which seems highly likely, the overall effect on magnetizing the iron could be surprisingly low, as far as I am aware. Though I could be wrong on this.

edit - ahh, reading through you mean during the experiment, rather than it being left magnetized afterward.

During the test it should focus field lines within it. The overall strength of the field will remain the same, but field lines will be concentrated on the cage, meaning it does not propagate as far.

Though there should be people on here that will be able to explain this better than I can. And correct me if I am talking rubbish. I am solidly an amateur on this, and there are definitely some professionals floating about.

the iron enclosure was meant to contain the explosion not the field.

Good point - edited!

From a tiny bit of experience, I know that industrial electromagnets (think of the ones they use to pick up steel at a scrap yard) often have an iron/steel housing that is used as a "return path" for the field. The front face of the magnet has a field that projects out into the air, but the field on the back face gets channeled into the housing.

Alnico horseshoe magnets are often sold with a keeper bar: https://en.wikipedia.org/wiki/Magnet_keeper

Well you're going to need something that reacts to magnetic fields in some way. In that sense iron isn't an odd choice.

Anything that isn't susceptible to magnetic fields is not going to do much, even if its conductive that can only help against brief bursts.

I was waiting for Gordon Freeman to emerge from behind the machine with his crowbar...

Wouldn't that be a red letter day.

Half life 3 confirmed

It blows my mind that we can compress a magnetic field with chemical explosives. I wouldn't have expected them to interact much at all.

>> I wouldn't have expected them to interact much at all.

They don't interact directly:

https://en.wikipedia.org/wiki/Explosively_pumped_flux_compre...

This is the link I was looking for in the comments, thanks.

I'm kind of amazed they were even able to record a video in a 1200 Tesla magnetic field.

Magnetic fields tend to decay with distance from the source which helps.

And broadly speaking by the cube of the distance from the source apparently. But in this case it decays from a mind-boggling starting level by everyday life standards. If that camera is 5 meters away from the source the field there is still about 10 Tesla. I think that's about an order of magnitude more than most MRI machines for clinical purposes, and those already warrant a good deal of care with effects on metals.

MRI vendors require some parts be photographed at service. Standard tool for this is a phone camera. I don’t know if this applies above 3T but at that level it’s all fine. And as for clinical field strengths - there are 7T scanners being marketed, but they are rare.

I personally don't work with machines like that, and never have, but I imagine most service would be out of the question without bringing down the magnetic field? If the magnet is not active, certainly consumer electronics could be used even near it. If the magnet is active at anything close to it's operation level, I'm seriously skeptical that a cell phone would fare okay close to it. Have you tried for yourself? Are you sure that the photos you've been in touch with were not rather taken at about 0T ?

Nearly all service work is done with the magnetic field up as ramping down is a massive deal. iPhones and iPads work fine until very close and it’s what the documentation is kept on for the vendors I know (Siemens and GE, Philips use Microsoft gear). Philips require photos of the cold head, which is pretty close in. Get too close to the bore and they turn off for a bit, which is probably due to cutting flux lines quickly. Id suspect it doesn’t help their lifespan but I’ve yet to see it kill a phone.

Reminds me of the scene at the end of Real Genius when they get their laser chemical laser to finally work and it puts a hole through the building.

Could you put a machine (that wasn't powered by TNT or something equally crazy) into a space ship for protection from cosmic rays? Is that something people are looking into?

I don't have a source on hand but I have read some study that theorized a very powerful electromagnet in a mars-sun lagrange point could be used to create a magnetic field to shield mars from cosmic radiation in a similar way to earth's magnetosphere. I seem to remember the power needed being (obviously) very large but surprisingly not many orders of magnitude out of plausibility. For a much smaller entity than a planet (spaceship) it may be possible with a low enough power consumption to make it possible. I would imagine there would be many many engineering concerns with having such a high powered magnet in your spaceship though.

I think the most likely doomsday scenario involves this type of weapon.

Now my question is, can it damage SSD? Or interfere with my wifi?

Is it strong enough to alter my brain?

Some examples of Tesla unit: https://en.wikipedia.org/wiki/Tesla_(unit)#Examples & https://en.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_...

8 T – the strength of LHC magnets

11.75 T – the strength of INUMAC magnets, largest MRI scanner

16 T – magnetic field strength required to levitate a frog

17.6 T – strongest field trapped in a superconductor in a lab as of July 2014

35.4 T – the current (2009) world record for a superconducting electromagnet in a background magnetic field

45 T – the current (2015) world record for continuous field magnets

100 T - Strongest pulsed non-destructive magnetic field produced in a laboratory

1200 T - Record for indoor pulsed magnetic field, (University of Tokyo, 2018)

2800 T - Record for human produced, pulsed magnetic field, (VNIIEF, 2001)

1 MT - 100 MT - Strength of a neutron star

Wow, 2800T is .28% of a neutron star? That is pretty impressive.

Vice really needs to hire some proofreaders.

I hate when I see a sciency article from them. They are great with human interest stuff (if you like their spin) but the technical stuff is always lacking. You can tell where the writer hits their wall of undertanding and tries to fill it with quotes instead of working with someone knowlegable on the subject.

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