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News & Media

Latest ITER Newsline

  • The magnet lab next door

    Two and a half years ago ITER and the French Alternative Energies and Atomic Energy Commission (CEA) entered a collaborationto prepare for the challenging task [...]

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  • Activity on every floor

    At every floor of the Tokamak Complex—from the lowest underground level (B2) all the way to the second regular level of the bioshield (L2)—there is intense acti [...]

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  • Bringing the Research Plan up to date

    The ITER Research Plan is an ITER baseline document which outlines the main lines of science and technology research derived from the project's mission goals. [...]

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  • Further validation for ring magnet fabrication

    Once a component mockup has been produced—and before fabrication can begin on the actual component or system—a manufacturing readiness review is required to ens [...]

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  • First central solenoid module ready for heat treatment

    In a major milestone, the US contractor responsible for the fabrication of the ITER central solenoid has successfully joined seven individual coil sections, or [...]

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Of Interest

See archived articles

Colour me a plasma

-Phil Dooley, EFDA

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.


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