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Superconductors and high voltage

  1. Apr 25, 2009 #1
    I have an idea to build a electromagnet out of superconducting wire out of the Tl2Ba4Ca2Cu10Ox superconductor discovered earlier this year that's superconducting at 40 degrees below zero in Fahrenheit and i'm wanting to supply 1 million volts or a little more to it and see what happens. and since its a superconductor and will have virtually have no resistance will i not need that thick of insulation since the least resistance path will be through the wire? Any help will be appreciated thanks.
     
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  3. Apr 25, 2009 #2

    MATLABdude

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    Ohm's Law is:
    V = I * R

    Consequently, with 0 resistance, you'll have infinite current. (In practice, the current will rise to the point where magnetic quenching occurs, and the current that's circulating about screeches to a spectacular halt).

    They're normally inductively pumped, and not directly hooked up to a power supply (as I understand it).

    What's your background in? Not to be a downer, but this question, along with the other one about making a million volt power supply leads me to question whether you have the technical wherewithal and access to the necessary materials to carry out your plan.

    Also, a place to get started, superconducting magnet:
    http://en.wikipedia.org/wiki/Superconducting_magnet
     
  4. Apr 25, 2009 #3

    vk6kro

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    Hi,

    If you want to play with high voltages, get a small Van Der Graaf generator.
    On a dry day even a small one can be so scary you won't want to go anywhere near it.

    Superconductors will be fun when the price comes down and the superconducting temperature gets up closer to room temperature, but even then they will not be suitable for high voltage low current work.
    They are best where very high currents are used, like making powerful magnets for levitation and particle acceleration.

    A coil that can generate such high voltages will have a lot of inductance and this will cause the high voltage to spark through insulation even if there was no resistance. So, you would certainly need excellent insulation.
     
  5. Apr 25, 2009 #4

    f95toli

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    There are quite a few problems with your idea:

    First of all, AFAIK there is no HTS material with a Tc of over 230K (at least not at ambient pressure, I don't remember what the record is at high pressures). Isn't Tc of Tl2Ba4Ca2Cu10Ox (I don't even remember if that is the correct formula) something like 120K?
    Also, are you sure that it is even possible to make a wire out of it? My guess would be no(making HTS cables is quite tricky, it took years of research to design the first generation of practcal cables and even longer to come up with the generation that is now becoming available).

    Secondly, you can't voltage bias something with zero dc resistance, there is no way to apply even 1V to a superconducting wire; if you try you will just force your source to try to deliver as much current as it can.

    Thirdly, now even if we assume that you can actually find a source which could both deliver 1MV and a resonable amount current this still won't get you anywhere. All that will happen as you try to increse the voltage is that the current will rapidly increase (it won't be infinite since it will be limited by the resistive parts of the circuit); sooner or later you will reach the critical current of the superconductor; the voltage will now rapidly increse and something will melt....¨
    The current when this happens will be significant: Jc varies quite a bit between different superconductors and obviously also depends on how close to Tc you are; but if we assume that you are at 0.7Tc or so Jc will probably be in the range 10^4-10^5 A/cm^2 or so

    Btw, Jc tests are done using CURRENT sources and the compliance is set to prevent them from deliving too much power to the DUT.
     
  6. Apr 26, 2009 #5
    ok well i don't know a lot about the million volt set-ups ive taken classes in electricity and i understand a lot about that. i'm not wanting something to just shot a projectile my idea is completely different ive explained my idea on here once before and i got deleted so i was just trying to figure it out on my own without help but anyways heres my idea. use a ring instead of a metal bar that isn't composed of ferrous material so it doesn't get affected by the magnetic field im producing and have some ferrous pieces bolted to the ring in strategic places and have a coil on the top right and bottom of course youll need a way more elaborate design than this this is just the basic idea. i want to make the top right and bottom coil and make the ring spin clockwise lets say and then have a fourth ring on the left working against the direction of the ring. and after its spinning so fast turn that one on but it won't be able to actualy stop the ring just constantly applying a force against it so i can have an upwards force on the coil and try to get thrust out of this idea. i believe it will work i know ur not supposed to be able to make linear force with centrifugal force but im going for it. i think it will work. i have a few ideas to try out with times to fire all the coils i just need to build this thing then ill go from there. and your question about superconductors not going about 130k go to superconductors.org it will tell u about this one it was only discovered a month or 2 ago and they say that they released it without a patent since were so close to being able to have a superconductor at room temperature they took one that was discovered in janruary of this year i believe and replaced one of the items with thallium oxide and got one that was superconducting at supposedly 40 degrees Fahrenheit. thanks for the replys
     
  7. Apr 26, 2009 #6
    sorry i have a correction i don't know where i got that formula from its Tl5Ba4Ca2Cu9Oy for the superconductor i want to make.
     
  8. Apr 26, 2009 #7
    Umm. you have no idea how to generate 1MV, do you?
     
  9. Apr 26, 2009 #8
    not realy thought about a tesla coil id like to do it without capacitors but i don't know if u can.
     
  10. Apr 30, 2009 #9
    Roughly how many amps will you need for this coil?
     
  11. May 3, 2009 #10
    i don't know how many amps. i need a very powerful electromagnet.
     
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