Why does a plasma ball emit light?

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    Ball Lighting Plasma
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Discussion Overview

The discussion revolves around the mechanisms behind light emission in a plasma ball, exploring the interactions of ions and electrons within the gas mixture. Participants delve into the physical principles and clarify misconceptions related to electron-nucleus interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that light emission is due to ions colliding with neutral gas molecules, which become excited and release energy as light when returning to their ground state.
  • Others argue against the idea that electrons impact the nucleus, suggesting that the light emitted is due to electrons falling back into vacancies left by ionization, with the color depending on the gas element.
  • A later reply questions the categorical rejection of electron-nucleus interactions, suggesting that in the presence of ionized hydrogen, such interactions could theoretically occur, although they would produce invisible wavelengths.
  • Some participants emphasize the importance of clarifying that the plasma ball contains a mixture of noble gases and that the purity of these gases may affect the light emission.
  • There is a contention regarding the adequacy of explanations provided to beginners, with some suggesting that more detailed responses would be beneficial for understanding the underlying quantum physics.

Areas of Agreement / Disagreement

Participants express differing views on the role of electron-nucleus interactions in light emission, with no consensus reached on the implications of these interactions. The discussion remains unresolved regarding the clarity and depth of explanations suitable for beginners.

Contextual Notes

Participants note that the discussion is focused on a practical demonstration (the plasma ball) and that assumptions about the purity of the gas mixture and the nature of interactions are not fully explored.

ahmeds
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TL;DR
Plasma ball ligting
Is the cause of the lighting due to the impact of electrons with the nucleus
 
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Can you explain why plasma ball emit light……….its long article in wiki i do not understand
 
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The basic idea is that a high voltage produces and accelerates ions. Those ions collide with neutral gas molecules which becomes excited. When the excited gas molecule relaxes to the ground state, the energy from being excited is released as light.
 
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ahmeds said:
Is the cause of the lighting due to the impact of electrons with the nucleus
No, not the nucleus.
To put it in non-physical language ...
The electric field in the plasma ball, tears electrons away from the outside surface of the gas atoms, leaving empty holes. The light is emitted when electrons fall back into those holes. The colour of the light is determined by the element and the depth of the hole.
 
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Baluncore said:
No, not the nucleus.
Imo that's a bit sweeping. If there are ionised Hydrogen atoms about, there 'could' be an interaction with a proton (H+ ion / nucleus).
To be fair, though, the Lyman Series of spectral lines, which are due to electron / proton transitions are of invisible, very short wavelengths.
Visible lines tend to be produced from interaction with ions, other than Hydrogen, that are only partly ionised.
 
sophiecentaur said:
Imo that's a bit sweeping. If there are ionised Hydrogen atoms about, there 'could' be an interaction with a proton (H+ ion / nucleus).
This is not about any hydrogen ions that might be about.
sophiecentaur said:
Visible lines tend to be produced from interaction with ions, other than Hydrogen, that are only partly ionised.
To quote Wikipedia, the sphere is; "filled with noble gases, usually a mixture of neon, krypton, and xenon".
 
Baluncore said:
This is not about any hydrogen ions that might be about.

Baluncore said:
To quote Wikipedia, the sphere is; "filled with noble gases, usually a mixture of neon, krypton, and xenon".
We are discussing a real toy / cheap demo with a mixture of gases. It would be unlikely that the contents of the globe would be of high purity. The law of diminishing returns applies and this gadget has to sell at a reasonable price. The contents would be of similar purity to common or garden balloon gas. (Not so easy to come by these days.)

But my problem was with your categorical "no" about electrons hitting a nucleus. The "no" is a sweeping statement and could be mis-leading. That's all.
 
sophiecentaur said:
We are discussing a real toy / cheap demo with a mixture of gases.
That is correct. The gas mix is unimportant, so long as it works. Any UV emitted will not be "seen" directly, but may increase the ionisation of the plasma, which may then emit visible light.
sophiecentaur said:
But my problem was with your categorical "no" about electrons hitting a nucleus. The "no" is a sweeping statement and could be mis-leading. That's all.
This was a beginners question, so I went for understanding the basic principle. The "impact of electrons with the nucleus", needed to be clearly eliminated, before understanding the quantum physics of visible light.
 
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Baluncore said:
This was a beginners question, so I went for understanding the basic principle. The "impact of electrons with the nucleus", needed to be clearly eliminated, before understanding the quantum physics of visible light.
Yes but a 'sufficient' answer would not usually be a minimalist answer. A beginner would surely need to have it pointed out that only one electron would be missing from an atom. That would mean that the collision would involve interaction with the nucleus and the rest of the electrons. It costs nothing to expand on the word "no", particularly when helping a beginner. We know that a recombining electron goes nowhere near the nucleus.
 
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berkeman said:
No.
sophiecentaur said:
It costs nothing to expand on the word "no", particularly when helping a beginner.
Baluncore said:
No, not the nucleus.
sophiecentaur said:
We know that a recombining electron goes nowhere near the nucleus.
YES.
 
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