Results 1 to 6 of 6

Thread: Plasma!

  1. #1
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default Plasma!



    Thanks!


    Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  2. #2

    Default

    what is that?

  3. #3
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default

    Originally posted by munfai
    what is that?
    A plasma ball...I guess that's what it's called.

    One of those glass balls with a near vacumm inside and a very high voltage electrode.

    The high voltage causes the gas to become conductive and as the electrons travel from the electrode to the inner surface of the glass, they form purplish trails.

    - Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  4. #4
    Member
    Join Date
    Dec 2002
    Location
    Singapore
    Posts
    64

    Default

    Originally posted by roygoh
    A plasma ball...I guess that's what it's called.

    One of those glass balls with a near vacumm inside and a very high voltage electrode.

    The high voltage causes the gas to become conductive and as the electrons travel from the electrode to the inner surface of the glass, they form purplish trails.

    - Roy
    I never understood why the high voltage causes trails to form. If the gas becomes conductive, shouldn't the electrons travel isotropically? What causes the trails to form and not a spreading ball???

  5. #5
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default

    Originally posted by ckhaos
    I never understood why the high voltage causes trails to form. If the gas becomes conductive, shouldn't the electrons travel isotropically? What causes the trails to form and not a spreading ball???
    Hehe...this will bring the discussion way off the topic of photography.

    Base on my limited knowledge in physics, I would guess that the following are the reasons:

    1. The E-field in the chamber is never perfectly uniform. Neither the electrode nor the glass ball is perfectly shaped, and there are other factors like contamination etc to consder. This is also why touching the glass ball's outer surface would attract the trails towards the aread touched because of the change in potential on the inner surface.

    2. Avalanch effect. I don't know how to describe this, but the analogy is lightning streaks. Once the lowest energy path is found, the accumulated charge will follow this path for discharging.

    I have no physics degree, so I am just as curious and only guessing here.

    What do you think?

    - Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  6. #6
    Member
    Join Date
    May 2003
    Location
    Earth, Solar System, Milky Way
    Posts
    154

    Default

    Saw a nice one in UK selling for less than S$60. It also reacts with sound! Put the subwoofer beside it and watch the plasma ball thump along. I'm still considering whether I should buy it or save the money for more photography accessories.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •