Focusing Magnetic Fields (Halbach vs. Back Iron)

[@Alhussainba]

I liked the video after minute, went back to full screen, after 3 minutes I exited the full screen and liked the video again but I have already liked it, back to full screen, at 6 minutes the story repeats. I really love informative clear videos like this.

[@VeridicusFicta]

Absolutely amazing experiment and I love the way you presented your data! Beautiful stuff!!!

[@1495978707]

This is some good old school style KZbin, I love it

[@matteof8057]

damn right

[@noutram1000]

Hi, this deserves more views, some good science here, thx. The motor you show seems to be a radial flux type, have you made any axial flux motors with Halbachs? (I'm considering building one with two PM rotors and one electro-stator in the middle and wonder how Halbach might be built into both 'ends'... )

[@zdenekvalek1538]

Thank you for nice experiment. The back iron for standard configuration would help much more if it was much closer (touching the magnets) and it is there to close the magnetic circuit on the back side. It helps the magnetic flux, because with back iron it doesn't need to overcome magnetic resistance on back side. And it also prevents electromagnetic waves/fields outside the motor. Also there is normally gap between south and north pole magnets to avoid magnetic circuit shortcut between the magnets. It also improves strength. Anyway, your experiment was interesting for me as I did not know much about the Halbach array.

[@tribulationcoming]

This is good stuff, a tremendous amount of work and understanding. This helps our understanding of how the Halbach array works. A great deal of explanation of a complicated subject.

[@jonahjin4396]

such linear halbach array is applied in many electronic products like ipad. Also, the electric motor of Tesla 3 also use linear halbach (4 rectangular neodymium magnets glued together) to enhance the torque. It's always fascinating to me when I see those brilliant applications of permanent magnets.

[@user-wo9ey1xg1o]

I'm trying to make a generator of my own design and this info is great, didn't know back iron would increase the strength also helps the frame I have in mind, Halbach and Back Iron frame. Thank you. 👍

[@jimmaxwell2259]

The image at 4:18 showing the Halbach w/ Backiron looks to me as though the middle magnet is orientated wrongly?? I expected it to look the same as the image to the left without the backiron. Minor point, but an overall fantastic presentation. Great work.

[@BenjaminMarshallScienceMan]

Yeah, that's just an error with the graphic. The way it was actually tested is the same as your expectation.

[@BooBaddyBig]

I found that there wasn't much difference between a back iron and Halbach array. The back iron very nearly doubles the effective magnet height. For relatively short magnets that does almost the same as a Halbach array. For taller arrangements, the Halbach array may win (I didn't check). But the back iron has to touch the magnets. The main advantage of back iron is that the arrangement tends to more or less self assemble whereas Halbach arrays disassemble.

[@captainamazing1356]

Fantastic data and very well done 👍

[@jimmym2719]

That’s something i learned today, thank you bro for sharing 💕

[@SandBox86]

Thanks for this videos, for the information you share, I recently developed some new concepts and watching you was useful to be sure I wasn't going the wrong way

[@BenjaminMarshallScienceMan]

You're welcome! If you build anything cool, please show it to me!

[@SandBox86]

@@BenjaminMarshallScienceMan I'm working in COMSOL Multiphysics it's a nice piece of art. I was going to simulate this to see how the flux changes in every centerpiece. If you want 3D models I can make them no cost at all, I'm just a good boy.

[@BrentLeVasseur]

The outside ring would channel and direct the magnetic flow through the iron itself rather than letting it spill out into space. It’s the same idea with using a transformer core. You don’t want the magnetic field spilling out into space, you want to focus it and keep it contained.

[@BrentLeVasseur]

With a hall bach array, the magnetic flux flows directly from each magnet pole to the other magnet, which makes adding backing useless. The only time you would want backing is with non-permanent magnets/electromagnets. The physical metal of the magnets themselves is your backing material in an array making additional backing redundant, adding only cost and weight.

[@Constellation3232]

You held that first setup to the camera so perfectly, i thought the inside was convex 😂 then you moved it and i was like 🤯

[@michaelwhite4260]

The graphs are off the charts!

[@zkoibito709]

You are the real life Peter Parker scientist. You almost look like him and sound like him in the earlier Spiderman movies. Go Webs Go. Magnetic Webs that is.

[@gatekeeper84]

I think the gap the plastic creates skews your results. You should glue the magnets together and test again.

[@Alrukitaf]

He already achieved a significant difference at 1mm gap and 5mm. So maybe gluing might increase the field at 9mm significantly also? But he only used a small amount of back iron. Most motors use considerably more back iron.

[@Archin-dn4bp]

Hello Benjamin! Is it possible to make a switchable halbach array like switchable magnets?

[@BenjaminMarshallScienceMan]

If you include a backiron behind your array, and then make a way that the primary magnets (the non-sideways ones) can rotate 180 degrees, then you could effectively turn the array on and off. By flipping the primary magnets, you're switching which side of the array is the strong side, and which side is the weak side. Adding the backiron provides a low reluctance path for flux, further weakening the array when turned 'off', and ensuring that the back side of the array is not too strong when turned 'off'. If you've ever seen a 'mag chuck', I'd be willing to bet that that is exactly how they work.

[@Alrukitaf]

Super effort and very interesting results. Hope this is repeatable with other research teams.

[@lyallcampbell5613]

Hey, great video. I was wondering does the thickness of the back iron need to be the same as that of the magnet to have any effect?

[@Ponk_80]

I find it kind of ironic that people keep doing the same mistakes as everyone else, thinking that fine-tuning is the answer to the problem, instead of trying out new ways, that actually might work. But hey, it just makes it that more easy for me to solve this problem, when everyone is being distracted by the magicians hand, instead of seeing what is actually going on.

[@morankurdistan4716]

it's super useful thanks

[@ShellHeinze]

Bloody brilliant!!

[@ricanteja]

Don't know if this was mentioned in the video but I suspect the back iron added little to the magnets configured in the Halbach orientation because of the weaker back facing magnetic field. Great stuff!

[@BenjaminMarshallScienceMan]

If you're referring to the graphic, that's just a mistake I made while drawing it.

[@ToyotaKTM]

So does the back iron go on the weak side of the Halbach array? Also, your graphic shows two magnets for the standard arrangement and three for the Halbach arangement but you actually used nine magnets for both configurations, right?

[@BenjaminMarshallScienceMan]

The back iron was placed on the weak side, yes. The graphic showing the arrangement of two and three magnets is just showing one pole. The tested configuration for each setup had four poles, and I averaged the reading for each pole together. The halbach arrangement uses three magnets per pole, but the outer two magnets can be shared by the neighboring poles. While the standard configuration uses two magnets per pole. Having a setup with four total poles results in the halbach array having nine magnets total, and the standard having eight total. If the array were configured into a loop, the halbach configuration and standard configuration would have the same number of magnets.

[@FirstLast-tx3yj]

@@BenjaminMarshallScienceMan i believe a fair comparison is only one with the same total number of magnets Or at least total magnet surface per pole The results would lead me to assume three magnets in traditional configuration would have higher curve area and possibly peak than the halback array

[@BenjaminMarshallScienceMan]

When the linear halbach array is closed into a circle (as it would be for a motor) it possesses the same number of magnets as a conventional array, since a pole in a halbach array shares its outer magnets with the neighboring poles, each pole only really uses 2 magnets. Also, the graphic pictured is showing the average field of every pole in the array rather than a single standalone pole. I personally think this is a fair comparison, but I probably could have made the graphic a little better.

[@s0meus3r]

Interesting work. Have you tried different shapes of iron ? Wander if for motors producing asymmetric field might increase the torque...

[@haley8004]

Awesome. I was going to do some similar investigations with Halbach and 3d printed motors. You're way ahead of me. I presume you've seen Christoph Laimer's videos? I like how he runs his wire close to the air gap, which probably relies less on the permeance of iron to conduct the field.

[@madDragon08]

Since the Halbach tests were using 3 magnets vs the 2 magnets in the same direction, how much.... wait, you were measuring across a string of magnets and not just two. Alright. I was confused for a moment thinking that only two magnets were used to test strength.

[@Dancer148]

Good R&D approach, but Hallbach 3 magnet configuration should be compared with also a 3 magnet default setup with or without back iron. Graphs will look the same?

[@dSquared0162]

Good study! Helps me a lot. Thanks. 👏👍

[@PremiumMind]

Thank you for your efforts. 💯

[@Fish-ub3wn]

10/10 much needed answer

[@BrentLeVasseur]

Have you had any luck sourcing custom cores from any manufacturers? I’m finding its difficult if you aren’t ordering thousands of them at a time.

[@keenheat3335]

apparently according to wiki, there is also halbach cylinder and halbach sphere configuration as well. The sphere configuration has around 4/3 times the ideal cylinder configuration given same amount of magnetic material. Not sure how to incorporate sphere configuration into a motor though, maybe two half spheres ? so the rotor housing can slide through. Also I wonder if you arrange regular electromagnetic in the same halbach array configuration, does it also increase its magnetic strength ? or is this a permanent magnetic specific feature ? great video btw

[@BenjaminMarshallScienceMan]

A motor with spherical rotors/stators does not sound ideal, since any magnets near the axis of rotation would not provide a significant moment of torque, but it might be worth testing out. As for halbach electromagnets, in a couple simple experiments it looks like arranging electromagnets into a halbach array works, but provides less benefit and take sup more space than simply increasing the amount of current flowing through your electromagnet.

[@MrDbertrand]

change your magnet geometry to "PUSH" the medium into a twisting vortex

[@whatelseison8970]

The reason adding back iron to the Halbach array did basically nothing is because they are basically the exact same thing for the same reason; which is generally to get as much of the PM's flux cutting the working turns of copper to which it's meant to be coupled and nothing else. Using high permeability materials to back an array of magnets has an effect very similar to that of the H.A.'s at a fraction of the price, but it comes at the cost of greater weight and lower performance. In short, you can't improve the performance of a high performance system by also adding a low cost alternative to that system. The iron is basically unmagnetized dead weight because the Halbach is not leaking any flux to which the iron could offer a more direct path. It might seem counter-intuitive and a bad thing that the field dies off faster with distance from the magnets but it's actually highly desirable and a direct consequence of these field configurations. What we mean when we talk about the strength of a magnet in Tesla's at a particular point or region in space is is the _magnetic flux density_ - . The more the field can be confined to the windings, the better the specific power and efficiency of a (synchronous) motor can be. The air gap between them does need to be made as small as possible though.

[@YouArtMusic-Oficial]

en todo caso en vez de hierro dulce deberia de utilizar una placa de mometal pero sigue sin tener mucho sentido pues el flujo se encontraria en sentido contrario , por lo que sigue siendo peso muerto ....

[@russellwilson5246]

hey the chart at 6 minuts shows 3 magnets used for hall bach and 2 magnets for standard..as an guy with absolutely no idea it seems an unfair comparison..i do understand here we are talking about focus not actual strenth...seems to me the back iron actualy takes strenth away (40%) but from the other side and reflects just 2% to the stator side.in an aplication like a bike the back iron would use more energy climbing hills than the 2% gain in magnetic strenth? but maybe if each of the 42 magnets gain 2% strenth maybe there could be a gain.in any case i would in my aplication be more interested in the weigh reduction.prhaps you could achive higher strenth by using diferen size magnets?..interesting stuff:)

[@Hellspooned2]

Would making a Halbach array in 45 degree rotation between each magnet instead of 90 degrees do anything?

[@BenjaminMarshallScienceMan]

So if you had 3 magnets in a row, initially all pointing the same direction.... I'm imagining that as you turn the outer two magnets to point inward, your array transitions from being symmetric to unidirectional. In other words, I think that having the magnets at a 45 degree angle would just make for a less good halbach? I'm obviously not an expert though.

[@nonsquid]

So if you print your stator Halbach array with magnetic filament, would that act as a magnetic backplate or shunt diffuser? If you printed a ring backplate out of magnetic filament with normal PLA as the standard stator, would that improve your motor strength?

[@craigjohnston3603]

Can you put two Halbach Arrays back to back. Weak side to weak side.

[@adolfovilla7547]

Very nice!

[@percyv5868]

hi benjamin , very good video! thx a lot. it provided me with the information needed! what was the thickness of the backiron? any specific steel type?

[@arkangel8709]

Hi Benjy, you look like a Super Hero cartoon character.!! With you're brushed on mustache.!! & You're "Baby Genius" Hiar - doe.!! Ha,ha, ha, HA go gett'em Benjy,!!

[@user-zr3io2ft1x]

did you perform this experiment on larger magnets array like 2 cm or thicker magnets ?

[@dagemworku6035]

Thanks buddy, it helped a lot. 👍

[@philadelphiaslim4144]

Brandon Marshall do you have social media of any sort? I'm about the same age and I've always been interested in future tech and learning about it and developing it. Would you be up to maybe emailing or something back n forth just to discuss different stuff and maybe get a lil interview from you.

[@jimmaxwell2259]

Question... in the Halbach array, what would be the effect of using lower strength magnets for the 'side orientations'? Would they still direct the field lines/flux through in the same way without detracting from the main power of the stator facing magnets?

[@BenjaminMarshallScienceMan]

I haven't tested varying strengths of the side-facing magnets, but I can only imagine that you'd want them to be as strong as possible.

[@russellwilson5246]

thanks i learnt more than the answer i was looking for..here was my question..on an out runner does the rotor have to be steel or iron?..can it be for example nylon for less weight?...ihave a direct drive bike motor and its too heavy..after watching your vid seems i can replace the outer rotor steel/iron with say nylon..it wont be strong enough to take spoke loads but i can mount it forward of the wheel and drive the wheel by chain...thank you and any thaughts you have would be grate.

[@lt5932]

Good job

[@BenjaminMarshallScienceMan]

Thanks dad.

[@lt5932]

@@BenjaminMarshallScienceMan Im proud of all my children.👍

[@RixtronixLAB]

Creative video, thanks :)

[@amirahmadi794]

thank you

[@gianbetos]

hi, if i want to make an axial motor o generator... how would it place the magnets???

[@aothe2239]

its gold

[@spath13]

Thanks for sharing 🙂

[@rozanug3390]

thanks

[@Ibian666]

Thanks for doing this.

[@BenjaminMarshallScienceMan]

You're welcome! I hope it has proven helpful.

[@Ibian666]

@@BenjaminMarshallScienceMan Do you happen to know if a percentage increase in magnetic strength results in a similar rise in electric output from a turbine, say from a windmill?

[@chrisclarke4664]

genius vibes

[@jonnupe1645]

Commenting for KZbin algorithm

[@MJohnRupert]

Center magnet orientation seems to be wrong @5.41 Halbach w/ Backiron configuration. Please check!

[@BenjaminMarshallScienceMan]

Yeah, I was initially intending to test the weak side of the halbach, so I drew the chart to reflect that. Then I decided that it'd be a better idea to test a halbach with a backiron, and forgot to update the graphic.

[@richardwalker9826]

i would like to know if anyone has ever tried using a magnetic setup like a halbach array to make a vacuum sealed portable or non-portable electricity generator that could possibly use a wind up spring or other source of power like solar? the possibilities are endless to create renewable sources of power generation if you can combine ideas, technology, and resources with practicle application

[@projectwes4573]

thanks for the video

[@KokoroDenshin]

sad, already paid for back plate iron lol wish i know this earlier😅

[@1kreature]

Magnet mass vs pole count pr area needs to be identical to compare strength properly...

[@BenjaminMarshallScienceMan]

Once you form a halbach array into a circle, the number of magnets and poles ends up being the same as a standard array since a pole within a halbach array shares its outer magnets with its neighboring poles. Even if you were only making a linear array, the entire halbach array would only require one extra magnet over a standard array for the same number of poles. You can see this in the video at 0:45. Each array has 4 poles, the halbach uses 9 magnets and the standard uses 8.

[@rottondog1473]

looks like the same area count. 2 @ standard for one pole vs. 1/2 +1+1/2 for the halbach and the other side of the 1/2 are for the next pole.

[@learneverything659]

Which kind of paper that one? How can I buy this

[@BenjaminMarshallScienceMan]

It's called 'Magnetic Viewing Film'. I bought it on Amazon very cheaply.

[@learneverything659]

@@BenjaminMarshallScienceMan Thank U so much for your reply.

[@enotdetcelfer]

Nice methodology for the most part, but testing 2 magnets in standard vs 3 magnets in halbach doesn't really compare the configurations honestly imo.

[@BenjaminMarshallScienceMan]

That's just the image. The actual readings came from magnets embedded in an actual array. Also the halbach pole is sort of composed of one and two half-magnets.

[@carolinebell4360]

Season are you

[@learneverything659]

How about that meter? How can I buy? and cost?

[@BenjaminMarshallScienceMan]

100 GBP on Amazon. www.amazon.co.uk/dp/B07KMYSP9Q/ref=cm_sw_r_cp_apa_fabc_x2.7FbDHWBVR9?_encoding=UTF8&psc=1

[@learneverything659]

@@BenjaminMarshallScienceMan Thank you dear

[@haley8004]

cheaper similar ones on Aliexpress. The magnet paper too.

[@BenjaminMarshallScienceMan]

I just use Amazon for the one day shipping in the UK.

[@learneverything659]

@@haley8004 Could you please suggest which brand is good one for both or send me the link

[@dustinswatsons9150]

Aw shot

[@shazidali8231]

Hii इंग्लिश सुपर है

[@expresull]

Halbach is not good for the generator !

[@kimlesage5900]

Why not?