Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • Cryoplant | A vertical displacement event

    Three vertical storage tanks have been installed since last week outside of the cryoplant. The operation requires two powerful cranes working in tandem but also [...]

    Read more

  • Science in Texas | ITER draws enthousiasm

    At its Annual Meeting in Austin, Texas, the American Association for the Advancement of Science, AAAS, invited participants to illustrate how investment in basi [...]

    Read more

  • Image of the week | In the belly of the (flying) whale

    On 15 February, 'Isabelle' and 'Jeanne,' the last of the ten toroidal field coils manufactured in France for the EU-Japan tokamak JT-60SA, were swallowed into t [...]

    Read more

  • Nuclear safety | "A pragmatic and creative approach"

    Safety is at the core of all nuclear activities. Over the past seven decades—since the first experimental reactor was brought to criticality in 1942—codes, stan [...]

    Read more

  • Intellectual property | Modernizing processes and practices

    'A wise man will always allow a fool to rob him of ideas without yelling 'Thief.' If he is wise, he has not been impoverished,' says Ben Hecht in A Child of the [...]

    Read more

Of Interest

See archived articles

Generating runaway electrons in JET to benefit ITER

EUROfusion

Like splashes of water: re-deposited, molten beryllium appears on tiles inside the JET vessel after dedicated experiments. (Click to view larger version...)
Like splashes of water: re-deposited, molten beryllium appears on tiles inside the JET vessel after dedicated experiments.
Recent images of JET interior tiles have shown, in graphic detail, the damage that can be caused by so-called 'runaway' electrons in JET plasmas.

In stable fusion plasmas, fast moving electrons are slowed down by collisions. The balance between acceleration and slowingdown due to collisions ensures that under usual circumstances the electrons have a normal thermal distribution of velocities within the confined plasma.

However, there are certain circumstances—especially just after a plasma has terminated or disrupted — where the 'slowing down' effect of collisions is diminished and indeed largely removed. In this situation, JET acts like a particle accelerator enabling 'runaway' electrons to be accelerated to velocities close to the speed of light.

When the beams of runaway electrons hit the beryllium wall tiles they can travel many centimetres through the material producing characteristic melt pools like the one shown here. Special experiments are designed in JET to create and understand the formation of runaway beams. Fortunately, since installation of JET's ITER-like Wall such events do not occur naturally and have to be deliberately generated for such studies.

The JET experiments are providing ITER with vital information on which strategies are effective at mitigating this threat.

Read the article on EuroFusion website.


return to the latest published articles