Subscribe options

Select your newsletters:

Please enter your email address:

@

News & Media

Latest ITER Newsline

  • FEC2020 | Seeking sponsors for 28th IAEA Fusion Energy Conference

    For only the third time since 1961, the International Atomic Energy Agency's Fusion Energy Conference will be taking place in France—hosted jointly by the Frenc [...]

    Read more

  • Nuclear safety | Under constant scrutiny

    Because one of the elements involved in the fusion reaction is the radioactive isotope tritium, and because the hydrogen fusion reaction itself generates a high [...]

    Read more

  • Power conversion | Alien structures and strange contraptions

    There are places in ITER that seem to belong to another world, places full of alien structures and strange contraptions. The feeling—a mixture of awe and puzzle [...]

    Read more

  • Tokamak Complex | A changing landscape

    For the past three years, the view from the top of the highest worksite crane has not changed much. Inside of the Tokamak Complex, 80 metres below, concrete gal [...]

    Read more

  • Ion cyclotron heating | How to pump 20 MW of power into 1 gram of plasma

    To power the ion cyclotron system, the ITER Organization and its partners are designing not only new antennas, which will be housed in the tokamak vessel, but a [...]

    Read more

Of Interest

See archived entries

Neutral beam diagnostics

Right in the line of the beam

Pierluigi Veltri, ITER Neutral Beam Section

A high-precision diagnostic is about to enter into service at the ITER Neutral Beam Test Facility, where scientists are testing key aspects of ITER's external heating powerhouse—neutral beam injection.

Sixteen carbon fibre composite tiles are being mounted on the STRIKE structure. These tiles will face the brunt of the SPIDER negative ion beam ... for short periods of time ... to characterize beam uniformity and divergence. (Click to view larger version...)
Sixteen carbon fibre composite tiles are being mounted on the STRIKE structure. These tiles will face the brunt of the SPIDER negative ion beam ... for short periods of time ... to characterize beam uniformity and divergence.
Last-phase assembly activities are underway on the STRIKE calorimeter at the ITER Neutral Beam Test Facility, as carbon tiles are installed on the supporting structure. STRIKE will be used on the first of the facility's test beds SPIDER, an ITER-scale negative ion source inaugurated last June.

STRIKE is the most remarkable diagnostic planned for the SPIDER beam—the only one able to measure beam uniformity and divergence at the same time. The principle is quite simple: the calorimeter will present a perpendicular surface made of carbon fibre composite (CFC) tiles to the beam. The power deposited by the beam on the front side of the tiles will be propagated in form of heat to the rear side, where a set of infrared cameras will detect and analyze the thermal pattern in order to reconstruct beam properties.

A CAD representation of the rear side of the STRIKE calorimeter, installed inside the SPIDER vessel perpendicular to the beam. In orange, the view cones of infrared cameras. (Click to view larger version...)
A CAD representation of the rear side of the STRIKE calorimeter, installed inside the SPIDER vessel perpendicular to the beam. In orange, the view cones of infrared cameras.
In order to preserve the pattern all the way through the calorimeter, it is fundamental to minimize the heat conduction along the directions perpendicular to the beam axis, while maintaining parallel conduction. For this reason, the tiles are made of carbon fibres that are packed and oriented in the direction parallel to the beam. Fabrication requires several months and is only possible in few locations around the world.

To fully intercept the SPIDER beam—which occupies approximately one square metre—16 carbon fibre composite tiles are needed. The tiles are kept in place by a metallic structure whose position can be remotely controlled in order to diagnose the beam at different distances from the source. The structure is also equipped with electrostatic sensors and thermocouples to provide additional information.

Even if the tiles are capable of sustaining temperatures in excess of 1,000 ˚C, they cannot withstand the full power (up to 6 MW) of the SPIDER beam for long periods; hence, for long pulses, the metallic structure of STRIKE opens to allow the beam to pass through and be intercepted further along by an alternative calorimeter, the actively cooled "beam dump."

Thanks to this high-tech instrument, scientists will be able to perform precision analysis on the SPIDER beam.


return to the latest published articles