Connect with us

Electron gun lightning.

Discussion in 'Electronic Basics' started by [email protected], Aug 18, 2005.

Scroll to continue with content
  1. Guest

    I was just thinking about electron guns and how they could
    theroretically staticly cherge metal they were aimed at. This gave me
    an idea. If I hung a mylar balloon a few inches from the ground, from a
    plastic insulative string, and shot an electron gun from a computer
    monitor at it; would the ballon build up a negative charge and shoot a
    lightning bolt to the ground?



    The can't theoretically charge metal they are aimed at. They only work when
    they are aimed at a charge............

    Here study up on how a CRT works and then tell us if you think your
    experiment will work..
  3. John  Larkin

    John Larkin Guest

    Sure they can. Whack a hunk of metal with electrons, and it'll go

    The trick would be to keep the balloon inflated in the vacuum you'd
    need to keep this kind of electron gun working. There are electron
    guns that can zot a beam through air, but that's a whole nother story.



    How are we going to "whack" this balloon with electrons?

    I think he wants to do it outside the tube. Are we gonna cut a hole in the
    face of the tube and run some clip leads from the anode to the balloon?
  5. John Larkin

    John Larkin Guest

    A regular CRT gun can't do this, as I think I noted. But there are
    electron guns with thin windows, usually beryllium, that have vacuum
    inside but let the beam escape into free air. It takes a pretty
    powerful beam, as in 100's of kilovolts, to travel any useful distance
    in air, but it is done, as for sterilizing foods and such.

    If you banged a metallic object with such a beam, it would acquire
    negative charge. And you'd maybe die from the incidental x-rays.



    Interesting, Sounds like momentum carries the beam past the anode? Perhaps
    a deflection coil to keep the beam off the Anode?

    I was thinking it might be easier for the OP to achieve his fireworks with a
    magnetron and a parabolic reflector. If I had a hunk of mylar I'd throw it
    in the microwave to see what happens....

    Of couse there might be some dangerous radiation to worry about here as
    well... Oh well, My kids are grown and wasent thinking of having anymore
  7. John Larkin

    John Larkin Guest

    Usually the beryllium window *is* the anode. If the electrons are
    going fast enough, most of them sail clean through, just slip berween
    the Be nuclei. Beryllium is the common choice because it's light and
    strong (a thin foil has to stand up to 15 psi differential) and the
    nuclei are small. Electrons will also happily sail through an anode
    with a hole in it, but then the vacuum would leak out.
    That wouldn't transfer charge.



    Okay, but most mylar balloons are "Alimunized Mylar" and perhaps with a
    little manipulation of the balloon we might be able to get some sparks
  9. me

    me Guest

    only with respect to some potential reference. Whack it hard enough and
    get bremstralung radiation...
  10. Guest

    At the time I wrote this I hadn't realized the the electrons could only
    travel in a vacum, it was a mistake I regreted less than an hour later.
    So... how about an ion-ray Gun?
  11. Guest

    I haven't had kids but hope to later in life, So...*nervous
    laughter*... Lets just forget about this idea.


    Electrons travel everywhere...

    I believe CRT's receiving tubes, etc.. are evacuated is to keep impurities
    out which would shorten the life of the cathode.
  13. Don Bruder

    Don Bruder Guest

    But they travel MUCH better in places where they aren't running into
    Tell ya what... Let's have you test that belief.

    Let's do a simple cookbook-style experiment, shall we?

    Open up your TV set, and pull the control board off the end of the
    picture tube. Probably have to wiggle it a bit - they're usually pretty

    In the middle of the ring of pins on the back of the tube, there's a
    little tit of thin glass where they melted it shut after drawing down
    the vacuum on it. Use a pair of needlenose pliers or similar to grab
    that little tit and bend it until you feel it crack and you hear a hiss,
    whistle, whoosh, or some similar "air in fast motion through small
    opening" noise.

    Once the noise stops, put the plug back on the tube - make sure you
    match up the keyway - and fire that puppy up.

    Report back on how well it works.

    Hint: Before you go destroying your TV set, lemme save you some effort.
    It ain't gonna work AT ALL. Electrons CAN travel through air in certain
    situations (think lightning - Charge flowing through an ionized channel
    of air), but not well. That's why air is generally considered an
    insulator. An electron beam is either absorbed or scatttered into
    uselessness by collisions with the atoms making up the air and/or any
    particles that might be suspended in it.


    Geeze Don, why so sarcastic?

    I said tubes are evacuated to keep impurities out, didn't feel like writing
    a smart-ass sarcastic dissertation on the subject. Are you saying that
    impurities will not affect the cathode?

    Tubes get gasy quite often, they don't just quite working they die a slow
    death. Degradation of the cathode plays a part in that death.

    In your experiment I am sure quite a number of things would go wrong,
    perhaps some arcing at the anode. Filaments might burn open. And if it
    tried to make a picture it probably wouldn't be perfect or long lived. Have
    you ever tried it?

    Go buy two light bulbs, very carefully let the air out one. Now fire em
    both up and see which one last longer.

    I was responding to the "Electrons only travel in a vacuum comment" It is
    simply not true. If it where my TV wouldn't need tube as I wouldn't be able
    to receive any signal to display on it
  15. Jasen Betts

    Jasen Betts Guest

    no. the electron gun won't function in the atmosphere.

    the voltage inside the computer monitor isn't enough to make a spark jump
    more than an inch or two through the air.

    however if you could get enough charge onto the balloon there would be a
    spark to ground if the ground didn't attract the baloon to it frist :)

  16. Jasen Betts

    Jasen Betts Guest

    well, yeah, electrons travel through cables too :)

    but my TV gets its signal from an antenna and radio waves aren't composed
    of electrons. they're composed of photons.



    Yes, but I do not have cable TV. ANd even the I am certain that somewhere
    along the line the signal was transmitted through through the air. i.e.
    sattelite, microwave STL link, ENG truck, etc etc...
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day