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News & Media

Latest ITER Newsline

  • Real-time collaboration delivers for fusion computing

    A key computing system for ITER is now being trialled at the European tokamak JET, following collaboration betweenteams at the UK's Culham Centre for Fusion Ene [...]

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  • The balance of power

    It comes as no surprise that the French railway operator SNCF is the largest consumer of electricity in the country—it takes a lot of megawatts to power 500 sup [...]

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  • "Dummy" winding takes shape

    As orange lights flash and machines softly hum, layer one of a 'dummy' pancake winding (the building block of a poloidal field coil) is taking shape on the wind [...]

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  • As big (and heavy) as a whale

    It was pouring when the two 35-metre-long quench tanks were delivered to the ITER site at 2:12 a.m. on Thursday 24 November. And it was still raining heavily on [...]

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  • A passage to India

    108 days, 10,200 kilometres, 16 countries, and only two flat tires. These are the remarkable statistics of a no-less-remarkable journey: a father and son who tr [...]

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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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