Subscribe options

Select your newsletters:

Please enter your email address:

@

Your email address will only be used for the purpose of sending you the ITER Organization publication(s) that you have requested. ITER Organization will not transfer your email address or other personal data to any other party or use it for commercial purposes.

If you change your mind, you can easily unsubscribe by clicking the unsubscribe option at the bottom of an email you've received from ITER Organization.

For more information, see our Privacy policy.

News & Media

Latest ITER Newsline

  • Cryopumps | First unit reaches ITER

    The ITER vacuum team, the European Domestic Agency Fusion for Energy, Research Instruments (RI), and the ITER Director-General were all excited to welcome the d [...]

    Read more

  • Tritium Plant Summit | A shared vision to prepare for delivery

    A summit organized at ITER Headquarters from 3 to 6 June brought together the international teams that will deliver the sub-systems of the ITER Tritium Plant. I [...]

    Read more

  • Image of the week | ITER Robots goes international

    Thinking outside the box, teamwork and ingenuity are the ingredients that make for a successful robotics engineer—all qualities that are cultivated by participa [...]

    Read more

  • In memoriam | Physicist Michael Lehnen

    The ITER Organization mourns the passing of an outstanding physicist and beloved colleague. It is with the deepest sadness and a profound sense of loss that we [...]

    Read more

  • Cross-sector advocacy | The fusion knights

    Developing fusion as a usable energy source requires an all-hands-on-deck approach. At last week's ITER workshop, fusion advocacy organizations showed the role [...]

    Read more

Of Interest

See archived entries

Colour me a plasma

Each element has its own colour, corresponding to the gaps between its electrons' energy levels. The human classification of today's plasma colour as salmon, or peach, or burnt sienna is quite irrelevant. But a fun discussion to have, nonetheless. (Click to view larger version...)
Each element has its own colour, corresponding to the gaps between its electrons' energy levels. The human classification of today's plasma colour as salmon, or peach, or burnt sienna is quite irrelevant. But a fun discussion to have, nonetheless.
Something that surprises many people when they see their first plasma pulse on a screen in the control room, is that the plasma is invisible. There is a bit of glow around the edges, and the divertor—the bottom area of the vessel where the plasma touches the tiles—glows red hot. But the core of the plasma, at something like 100 million degrees, is completely transparent.

This is a desirable characteristic — it means that there is no energy being lost via radiation. It comes about because the atoms of the hydrogen fuel have been completely stripped of their electrons, or ionised. When attached to a nucleus at lower temperatures, these electrons absorb and emit light as they jump between the energy levels, but once they are detached that mechanism is disabled, so no light is absorbed or emitted.

To become this transparent, of course all the electrons must be detached. There is a pink glow around the edges because the plasma is cooler and so some electrons are attached, but generally for deuterium and tritium atoms, their single electron is easily removed. But for all other elements, with more electrons, it is harder to remove every last one and therefore to completely prevent energy leaking out through in the form of radiation.

Read the full article at EFDA.


return to the latest published articles