Enable Recite

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

  • Cryolines | Out through the door, in through the roof

    Cooling fluids for the machine's magnets, thermal shield and cryopumps will travel to the Tokamak Building through a set of large multi-process pipes (cryolines [...]

    Read more

  • Image of the week | Next in line

    Of six ring-shaped coils required for the ITER Tokamak, poloidal field coil #6 (PF6) is the heaviest (400 tonnes) and the second smallest, with a diameter of 10 [...]

    Read more

  • Assembly tools | Strong base for a very heavy task

    The first part of the in-pit assembly tool has been installed in the Tokamak pit. When complete, the tool will stand more than 20 metres high and branch out in [...]

    Read more

  • Diagnostics | A stowaway on board toroidal field coil #8

    Hidden inside the steel case of the most recent toroidal field coil delivered to ITER—TF8, from Japan—is a unique and critical diagnostic device. Named after th [...]

    Read more

  • Vacuum vessel sector | A 90° tilt in mid-air

    Ever since ITER entered the machine assembly phase, some ten months ago, we have been treated to a few spectacular lifting operations. In May 2020, we watched t [...]

    Read more

Of Interest

See archived entries

Generating runaway electrons in JET to benefit ITER

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