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Banned on April 7, 2007 Registered Member #277
Joined: Fri Mar 03 2006, 10:15AM
Location: Florida
Posts: 157
"The late Klaus Halbach of Lawrence Livermore National Laboratories discovered an interesting permanent magnet configuration that concentrates magnetic flux on one side of the array and cancels (most of it) it on the other. He originally designed it for focusing the beams of particle accelerators,"...but it is also being considered for magnetic levitation trains due to most of it's magnetic field being detectable on only one side of the magnet array.
To test his discovery, I fabricated this Halbach array using five of these and it works generally as advertised. Strong magnetic field on one side, very weak magnetic field detected on the other side. Rather than relying on magnetic shielding, this approach uses field canceling technique, pretty cool. The band I used around the mags is aluminum. Some have said it comes frightening close to being a magnetic mono-pole, but I think that is a bit of an overstatement in my opinion. While it might be viewed by some as progress toward a monopole, I can't say that I am entirely comfortable with that interpretation. To my knowledge, true monopoles remain in the domain of predicted theory, While it is clearly not a true mono-pole, because the magnetic field is predominate on only one side of the array, the Halbach array offers one option that developers may be able to utilize to levitate high-speed trains. In compliance with one of the admins who implied, in the thread that has been closed down, that I've been a little light on the data-side of some of my posts, I've included a magnetic-flux graph (that I found on the web) depicting the general mag field of the Halbach array. Pertaining to data, I've already listed my awarded patents elsewhere on this site. Cudos to the late Klause Halbach for his creative thinking and discovering what may end up becoming a important part of our future, at least for train riders. CM
Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
It does have uses. I have read a paper about a circular Hallbach array with a bore at the center, where the magnetic field is even higher than the remenance (sp?) magnetisation of the magnets, in the example some 2T I believe. I also remember reading of it in the context of MagLev trains, but I guess it is useful whenevery you want to concentrate a permanent magnets field into the smallest possible volume.
Banned on April 7, 2007 Registered Member #277
Joined: Fri Mar 03 2006, 10:15AM
Location: Florida
Posts: 157
Indeed you are correct that circular Halbach arrays exists. Here is a pic of a circular Halbach array that I own. While it definitely isn't a mono-pole, it does behave considerably different that any other formation of magnets that I've ever used, very strong magnetic field in one section, very little magnetic field everywhere else. There are educated people who believe the Halbach array is anything but ridiculous, particularly when it comes to magnetic levitation train development. An old saying, "People who can't... throw rocks at those who can". The Halbach array has been applied in particle accelerators, and NASA is considering inductive tracks for launch assist, which may possibly use the Halbach arrays, so before rushing to use the term ridiculous with regard to the Halbach array topic, let's give the scientist and engineers who are working with it a few more years to see what they can accomplish especially with regards to mag trains. Concerning shielded speakers, I dunno, but looks like an area for someone to research. CM
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Andrew, I can't see how this thread is more open to ridicule than lots of others. "If clever arrangements of magnets amuse you so, maybe you should get one of those carboard faces where you can draw a beard with the iron filings!" I think that comparable comments could be made about most of the people and projects on this site. For example the levitated magnet I have is nothing more than an amusing arrangement of magnets etc. Yes, it does amuse me. I guess that makes me a bit of a geek. You may not have noticed but around here the geeks are the majority. For the record, any magnet shows 2 poles and some bits where the field is near zero. The Halbach array happens to have some properties that are potentially useful and, at least to some of us, amusing. OK, describing it as resembling a monople is a bit hyperbolic, but comparing it to a simple solenoid isn't very helpful either.
Registered Member #49
Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362
I'm not saying the Halbach array is without use, as its clearly a clever arrangement of magnets, but it is only that. I didn't mean to demean the concept, only the thread.
The truth of the matter is that hundreds, nay, thousands of devices shape fields with this "cancelling technique". Exploitation of superposition is so fundamental and commonplace that paying this kind of lip service to the Halbach Array is like spouting off about a "BLACKHOLE Simulator? TOILET Fabricated, Swallows ANYTHING!" I would have blasted threads similarly if they were to discuss Helmholtz coils as groundbreaking, or even a cyclotron as some kind of new and different achievement.
For fun, behold: THE MAURER DEVICE. After YEARS of research I have single handedly crafted a device which contains a magnetic void at its center! ANTIMATTER Contaiment UNIT? As we speak, THOUSANDS of scientists toil in UNDERGROUND labs to find a way to use THE MAURER DEVICE to save the world and make floating trains!
Banned on April 7, 2007 Registered Member #277
Joined: Fri Mar 03 2006, 10:15AM
Location: Florida
Posts: 157
It would show a lack of appreciation for the Halbach array to classify it as just another magnetic toy or oddity. Admittedly, there are many various ways to warp, cancel or otherwise modify magnetic fields of permanent magnets, but to find a permanent magnetic 'oddity' such as the Halbach array, that has far-reaching practical purposes, might be of casual interest to some that keep their eye on future technology trends. The Halbach array has already been used to prototype magnetic launch assist prototypes by subcontractors working for NASA, with reportedly good early phase results such as being able launch "... a 50-lb. load ... with only one pound of magnet" The next phase of funding allows for a 350 ft track to allow payloads to reach 0.5 mach on launch (prior to the rocket engines adding to the thrust). Marshall Center has come up with an informal estimate that accelerating a 120,000-lb. launch vehicle from a maglev track could use an equivalent of as little as $75 worth of electricity. My guess is that most here at 4hv.org don't agree that such strides in technology and performance are ridiculous, but that's just my opinion. However, if you feel these things are trivial or ridiculous, that's okay too. To each-his own, and I defend your right to your opinion. No harm done. CM
Registered Member #49
Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362
You're completely failing to filter through the hype about this.
It would show a lack of appreciation for the Halbach array to classify it as just another magnetic toy or oddity. Admittedly, there are many various ways to warp, cancel or otherwise modify magnetic fields of permanent magnets, but to find a permanent magnetic 'oddity' such as the Halbach array, that has far-reaching practical purposes, might be of casual interest to some that keep their eye on future technology trends.
It is one of countless "special" arrangements of permanent magnets. It is no more or less remarkable than any of them, apart from its ability to attract (haha, magnet joke) pyramid-power nutcases.
"... a 50-lb. load ... with only one pound of magnet"
The next phase of funding allows for a 350 ft track to allow payloads to reach 0.5 mach on launch (prior to the rocket engines adding to the thrust). Marshall Center has come up with an informal estimate that accelerating a 120,000-lb. launch vehicle from a maglev track could use an equivalent of as little as $75 worth of electricity.
You mashed separate projects in that article together. But either way, those figures are bullshit. $75 bucks of electricity is 625kWh. Thats enough to accelerate a 120klb payload to 300m/s ("launch" velocity is about 7000m/s). If we assume realistic efficiencies (30%), that becomes 164m/s. Even if there is rocket propulsion afterwords, the propellant savings is next to none.
I don't deny that Halbach arrays have many uses. They however are not the 'enabling' technology in any case.
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MONOPOLE Impersonator? HALBACH Array Fabricated (Flux Lines ADDED)
