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  1. 31 Mar '14 20:44 / 1 edit
    http://phys.org/news/2014-03-hfml-world-tesla-magnet.html#nRlv
    "...
    The High Field Magnet Laboratory (HFML) at the Radboud University Nijmegen set a new world record today: the generation of a continuous magnetic field of 38 tesla in a resistive (i.e. non-superconducting) magnet. Strong magnetic fields of this type are crucial for materials research. The HFML's design proves that expensive superconducting coils are not needed to achieve 38 tesla, which lowers the purchasing costs by a factor of ten. The new magnet will be officially commissioned on 10 April.

    Materials research creates an ongoing demand for stronger magnets, as higher magnetic fields allow more properties of important materials to be uncovered and investigated. In a magnetic field of 38 tesla, certain quantum effects are one hundred times stronger than in a field of 33 tesla, which, until now, was the maximum magnetic field available in the Radboud University lab. This is why, in 2011, the HFML began the very ambitious project to design a resistive magnet which would surpass the current world record of 36 tesla.

    A leap for science

    According to HFML researcher Dr. Uli Zeitler, the 38 tesla field is a big leap for science: "The step from 33 tesla to 38 tesla is very significant for us. We will be able to clarify the properties of materials faster and more efficiently, and this will provide a major boost to materials innovation and development. This is of interest to us at the HFML, as well as to external researchers who come to use our facilities. Experiments in such high magnetic fields are currently only possible in the 45 tesla hybrid magnet, a partially superconducting magnet in Tallahassee (USA), which is hugely overbooked and cannot satisfy all the demand. With our new 38 tesla magnet, we will make magnetic fields of this level available to a larger group of scientists."
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    ...
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    and they say they expect to develop a 45 tesla one at around year 2017.

    When they say " the generation of a continuous magnetic field of 38 tesla", roughly how "continuous"? -I ask because I vaguely remember reading some similar link that said that they could only maintain such massive magnetic field strengths for less than a nanosecond. Are they now talking about seconds or minutes here or what?
  2. Standard member sonhouse
    Fast and Curious
    31 Mar '14 23:56 / 2 edits
    Originally posted by humy
    http://phys.org/news/2014-03-hfml-world-tesla-magnet.html#nRlv
    "...
    The High Field Magnet Laboratory (HFML) at the Radboud University Nijmegen set a new world record today: the generation of a continuous magnetic field of 38 tesla in a resistive (i.e. non-superconducting) magnet. Strong magnetic fields of this type are crucial for materials research. The HFML ...[text shortened]... trengths for less than a nanosecond. Are they now talking about seconds or minutes here or what?
    Yes, seconds or minutes, did you see the little blip where they had some kind of worm in the field, it was floating? Magnetic levitation.

    I think the limiting factor there was the 20 megawatts it takes to run the thing! That is one huge electric bill, a good portion of the operating budget.

    There was a considerable effort to engineer cooling loops so it COULD run continuously, at least for a few minutes. Getting rid of 20 megawatts is a huge project in itself, they said 140 odd liters of water per SECOND.

    My sputtering machine has water cooling of the RF feed and the target cooling and we get by on 5 liters per MINUTE! 1 L/M in the RF lines (1500 watts of RF feeding the targets, max, at the medical frequency, 13.56 Mhz)

    This machine has two proteus flow meters, paddle wheel affairs that spin and have little magnets on the paddles which generates a small voltage that is amplified and turns into a go-no go signal, machine won't sputter if the water flow is too small, there is an adjustable schmidt trigger, probably a 339 chip and it sets what flow has to be there to run.

    Can't imagine setting the flow for 140 liters per SECOND though!

    20 megawatts takes about 5000 TONS of cooling, over 60 MILLION BTU's!

    I thought I had seen big when I worked at Firestone Tire and Rubber many moons ago, they had a 2000 horsepower electric motor which took several megawatts on startup and almost 2 megawatts when it ran, it ran at 200 RPM, was the size of a whole room and was geared down to 16 RPM! Talk about torque! It was used to power a grinder that took 500 pounds of rubber and oils and such and mix it down to near liquid, the stuff got HOT! then out the mixer and on to a line which had the stuff in a long line and run like taffy on rollers up and down about 5 feet in the air and spayed with water to cool down the rubber! Quite a machine. Called the "Banbury 27".
  3. Standard member Soothfast
    0,1,1,2,3,5,8,13,21,
    02 Apr '14 06:11
    45 teslas. So…is that a lot?
  4. 02 Apr '14 07:08 / 3 edits
    Originally posted by Soothfast
    45 teslas. So…is that a lot?
    Yes. For comparison, as far as I am aware, the strongest permanent room-temperature magnets are Neodymium magnets which can have magnet field strengths as high as about 1.4 teslas. You can get a feel for Neodymium magnets typical strength if you have ever had a fridge Neodymium magnet and noted the amount of force required to pull it off the fridge door despite the magnet being so small -the force you have to exert to pull it off considering the small size of the magnet might surprise you. Now, try and imagine 32 times that strength of magnetic pull! (32 times because 45 / 1.4 = ~32 )
  5. Standard member sonhouse
    Fast and Curious
    02 Apr '14 08:55 / 1 edit
    Originally posted by Soothfast
    45 teslas. So…is that a lot?
    The magnets used in MRI machines are around 10 tesla's or thereabouts. One of them killed a 5 yo boy when they activated the magnet, one of the hard fast rules is to not have any magnetic metals anywhere in the MRI room.

    So this one day, some assshole left a metal fire extinguisher in the room, actually on the far wall away from the MRI itself.

    It didn't matter, when the magnet was turned on, it caused the fire extinguisher to fly through the air and inside the round portion where your head is located for the scan. So it hit the little boy and killed him instantly because it was going so fast.

    That is a magnet 1/4th or less the power of those big guys.

    You have seen perhaps the electromagnets used in scrap iron yards where a crane hauls this magnet about a meter wide and plops it down on say, a car, and they turn on the field and it is strong enough to lift the whole dam car right into the air and then deposit it in a crusher.

    Those magnets are maybe 2 teslas or so.

    That can give you a rough idea of the power of these newer ones at 30 and 40+ tesla.

    A Tesla is 10,000 Gauss and a typical refrigerator magnet might be a few hundred Gauss so you can see by the numbers, a 45 Tesla magnet is 450,000 Gauss! We are talking major force here.

    At that level, the metals used to make the magnets can get deformed and the whole thing blow up like a bomb if they don't make the internal structure strong enough to take the tons and tons of force generated so you don't just take some kind of iron core and wrap regular magnet wire around it, you have to have very well designed core material and a LOT of cooling water to keep the thing from melting on the spot, those big puppies take something like 20 MILLION watts to run, so you can see why they use water at 150 odd liters per SECOND to keep the magnets cool.

    And that is only regular magnets, some of them use superconductors which have to be cooled in some cases to with in an inch of absolute zero, say 3 or 4 degrees Kelvin and the higher temp ones, at liquid nitrogen temps.