Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • Cryoplant | Filled from floor to ceiling

    The ITER cryoplant used to be a vast echoey chamber with 5,400 m² of interior space divided into two areas; now, it is filled from floor to ceiling with industr [...]

    Read more

  • Cryostat | Adjusting, welding, testing ...

    The assembly of the ITER cryostat—the stainless steel "thermos" that insulates the ultra-cold superconducting magnets from the environment—is progress [...]

    Read more

  • Tokamak Building | Full steam ahead

    In this central arena of the construction site, construction teams are active three shifts a day—two full work shifts and a third, at night, dedicated to moving [...]

    Read more

  • Poloidal field coils | Turning tables and hot resin

    One of only two manufacturing facilities located on the ITER site, the Poloidal Field Coils Winding Facility was constructed by Europe to house the winding, imp [...]

    Read more

  • Assembly Hall | One giant standing

    Two identical handling tools in the Assembly Hall will play a critical role in preparing ITER's nine vacuum vessel sectors for their final journey: transport by [...]

    Read more

Of Interest

See archived entries

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