Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • The crown's jewels

    They are the jewels of the concrete crown that will support the combined mass of the Tokamak and its surrounding cryostat: 18 perfectly polished, chrome-plated [...]

    Read more

  • "Making the best of fusion installations in Europe"

    With the recent addition of the Ukraine's Kharkov Institute for Physics and Technology (KIPT), the EUROfusion consortium now encompasses 30 European fusion labo [...]

    Read more

  • New cryostat manufacturing milestone

    They all gathered—members of the ITER-India team and contractor Larsen & Toubro—to mark a portentous moment: the start of manufacturing on the upper cylinde [...]

    Read more

  • Key power supply elements pass tests in Russia

    Since the signature of a Procurement Arrangement in 2011 with Russia for switching networks, fast discharge units, DC busbars and instrumentation—all key elemen [...]

    Read more

  • First vessel subassembly achieved in Europe

    Nine massive steel sectors deliveredby the Domestic Agencies of Europe (five sectors) and Korea (four sectors) will be welded together on site during the assemb [...]

    Read more

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.


return to the latest published articles