Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • Upending tool | How to raise a sleeping giant

    How will the teams on site raise components weighing up to 450 tonnes from their horizontal delivery configurations to the upright orientation needed for assemb [...]

    Read more

  • SOFT 2018 | Conference opens in antique setting

    The ancient theatre of Taormina, in northeast Sicily, was built by the Romans on the foundations of an earlier Greek theatre. Still used to this day, the round [...]

    Read more

  • Former Council Chair Iotti | "Everyone should be congratulated!"

    For those who dreamed ITER in the 1990s, a visit to the construction site today is like stepping into a miracle. For Bob Iotti, who has been associated with the [...]

    Read more

  • In-vessel coils | Conductor qualified for manufacturing

    For magnet coils operating inside of the vacuum vessel, conventional insulation schemes are not an option. ITER will rely on mineral-insulated conductor technol [...]

    Read more

  • ITER Research Plan | The 400-page scenario

    The ITER Organization has just made publically available the most recent version of the ITER Research Plan, a 400-page document that describes the present visio [...]

    Read more

Of Interest

See archived entries

Record plasma fluence exposure in UC San Diego test stand

R.P. Doerner and the PISCES team, UCSD

The retention measurements are plotted at the right against the database contained in an MIT report (#PSFC/RR-10-4) which addresses this issue. Also evident in the plot is that the high plasma flux achievable in PISCES-B (1.5 × 1023 m-2s-1) results in a lower level of retention, compared to the data contained in the MIT report which were collected under lower flux conditions. (Click to view larger version...)
The retention measurements are plotted at the right against the database contained in an MIT report (#PSFC/RR-10-4) which addresses this issue. Also evident in the plot is that the high plasma flux achievable in PISCES-B (1.5 × 1023 m-2s-1) results in a lower level of retention, compared to the data contained in the MIT report which were collected under lower flux conditions.
The PISCES-B device, located at the University of California San Diego (US), is a linear plasma test stand whose mission is to examine plasma-materials interactions for ITER and future DEMO devices.

In late 2014, PISCES-B was used for a series of high-fluence plasma exposures to investigate the deuterium fuel retention properties of tungsten when exposed to continuous plasma bombardment. The goal was to determine whether the fuel retention in the tungsten saturates with fluence, or continues to increase as a function of the plasma exposure time.

The deuterium particle fluence was varied by almost three orders of magnitude with the maximum deuterium atom fluence being 2 × 1028 m-2. To achieve the maximum fluence exposure, the PISCES-B device was run continuously for over 30 hours, reaching a fluence equivalent to 50 full-power 400-second ITER deuterium-tritium plasma pulses.

The experiment demonstrates the ability of linear plasma devices to operate in true steady state and to provide a test platform which can replicate plasma-material interaction conditions relevant to future DEMO reactors.

During pure deuterium plasma exposure, retention results indicate that saturation is not reached and that retention scales as the square root of time, indicative of diffusion dominating the fuel uptake of the tungsten.

The retention measurements are plotted in the graph at right against the database contained in an MIT report (#PSFC/RR-10-4) which addresses this issue. Also evident in the plot is that the high plasma flux achievable in PISCES-B (1.5 × 1023 m-2s-1) results in a lower level of retention, compared to the data contained in the MIT report which were collected under lower flux conditions.

However, measurements performed while sculpting the PISCES plasma to replicate a burning plasma, by adding a small amount (5 percent) of helium to the incident deuterium plasma, indicate the deuterium uptake in the target is severely inhibited. The diffusion barrier provided naturally by the helium ash contained in a burning plasma could alleviate many tritium-related concerns in future fusion reactors with tungsten plasma-facing materials.


return to the latest published articles