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Helmholtz coil based air thruster?

  1. Jan 25, 2013 #1
    Material in context is in a different color (blue)

    Okay I'd like to first begin by claiming/stating a few things. One I'd like someone with the proper/accurate knowledge to evaluate my idea which may already have existed preceding tonight which is when I thought of applying some things I had seen in the past to make an Earth Atmosphere based ionization/acceleration propulsion substitute to fuel based technology such as piston engines / jet engines.

    This is what I would improperly call a "Mass flow accelerator" device. I'm not claiming to be a genuine noble inventor or something although if no one else has thought of this (highly doubtful) cool. Regardless, a brief delusional thought entered my mind that this technology would be like Robard Hughes and his Tricone drill bit (A lot of money)

    I was partially interested in this idea recently because of one of many videos I had been watching on Elon Musk's interviews where he mentioned Electric Aircraft. A brief search on that suggested simply replacing the initial rotational component normally done by a gas piston engine or combustive section of a jet engine by an electric motor. Makes sense, very straight forward. But what about moving air itself?

    Then we go to "Hall effect thrusters" "Lifter devices" which the latter is close to what I had in mind though I had always been discouraged by the fact that it required a lot of electricity to lift a small amount of weight.

    So to begin, I began doing some research on the subject. I was a Physics and Engineering student in SUNY Fredonia and at the time I had it in my mind that the university was awful and that I suffered because it was an awful school but now (and I suspected before) that was not the case rather I was just lazy and impartial to my studies. Mindless if you will and regretful when I later dropped out and joined the military to pick up where I left of.

    Anyway I am sorry to bring that up but it defines my credibility as someone who may have a clue but does not know exactly and accurately what he is talking about. That is why I am here. I suppose I can't lie that I had hoped this idea would be a "it made me a billionaire!" kind of idea but seeing as I have a lot of math to do which isn't an excuse really rather my education sucked because of myself and I am rather a "philantrophist" in some degree, if someone took this idea and developed it. Good! I hope it replaces all things driven by fossil fuels.

    Now to actually get to it. (You should note that I will highlight the relevant material to the question).

    The primary concerns in my head are as follows.

    Density and electronegativity of the most prevalent gases nitrogen and oxygen
    Potential required and size of duct to begin ionization
    Magnitude of magnetic field required to accelerate ionized Earth atmosphere gas
    Size of air loop (necessary? referencing from cyclotron designs)
    Does a Helmholtz coil do any accelerating or is it fixed?
    Is a nozzle needed? (eg subsonic to supersonic)
    Can a hybrid be made so that this "propulsor" can operate in and out of Earth.
    Can it be sustained for long periods of times by batteries

    A simple diagram exists below, I just thought it would look something like this. Note that I did not draw the helmholtz coils which would be parallel to the coiling of the air duct as far as I understand.

    I should also note that I somewhat understand the basis of a Helmholtz coil and the apparatus's intended function (to depict charge to mass ratio) that was the lab that I used this device for. I also understand that high velocity electrons were produced (thermions?) from the electron gun and the circular pattern seen (glowing circle) was a combination of the presence of a uniform magnetic field and the "noble" gas that was in the tube or rather an ionizing gas (electrons colliding with gas) this sort of brings in mind the problem associated with trying to use Oxygen and Nitrogen as a working medium. There must be a reason why gases like Xenon and Argon are preferred? Besides Density and possibly Electronegativity?

    I also had a side question/note could it be possible to develop rotational devices based on enclosed mediums? Fluid if you will. If a shaft was built somehow like a vacuum attached to a moving fluid, the fluid which is caused to rotate by ionization/acceleration could drive the shaft. With added benefits of fluid bearings and such it could make for a good rotational device? Must already exists or a fundamental misunderstanding on my part.

    Thanks if anyone decides to help. I am sorry if I present myself poorly.
    I am not looking for pity, only mentioned things for context.


    Yeah this is probably a really dumb idea now that I think about it again. But please evaluate it and tell me why it is dumb.
  2. jcsd
  3. Jan 25, 2013 #2


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    If you ionize air, you have a plasma with positive and negative charges. The total force on any part of air would be zero, unless you get significant charge separation - and what do you do with the separated charges afterwards?
    In the frame of the coils (=frame of the airplane/rocket), a magnetic field will not increase the velocity of charges, where do you expect thrust if your flow in and out goes in the same direction?

    Even if you somehow manage to get any (!) acceleration, where is the advantage compared to a simple propeller? No moving parts, fine, but what about the efficiency? Ionization is a very expensive process in terms of energy.
  4. Jan 25, 2013 #3
    Just a random guess, what about a dual filter that separates each "charges" then an appropriate magnetic field is applied to that charge?

    What do you mean that my "flow in and out" goes in the same direction? I thought I had depicted that the "atmosphere" to be ionized comes in from the left side then supposedly after being accelerated goes to the right direction.

    Yes I understand what you're saying. I just had a hard time figuring out how people would make "electric jets" without the process of igniting the compressed air with a fuel of some sort

    I am really glad for your response. As I said this isn't really my thing (maybe I didn't say that) it was a random thought/idea and thus is a good example of diffidence not being a good thing. Well I suppose for most people who are not geniuses.
  5. Jan 25, 2013 #4


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    I doubt that you will get two different air flows. Probably electrons landing on an electrode, and positively charged air remaining.

    => air moves to the right in both cases
  6. Jan 25, 2013 #5
    So are you trying to say that this sort of a propulsor works primarily by action and reaction? Like a rocket?
  7. Jan 26, 2013 #6


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    It is simple: you cannot violate momentum conservation. To get thrust in one direction, you have to accelerate matter in the opposite direction.
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