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

  • Art and ITER | Two sisters, two suns and a monument to fusion

    Amid the gentle slopes of Asciano, Italy, there stands a stone window that frames the Sun on the summer solstice. It looks as though it might have always been t [...]

    Read more

  • Staff | The men and women of ITER

    They hail from Ahmedabad and Prague ... from Naka and Moscow ... from Seoul, Hefei, Atlanta and hundreds of other towns and cities across the 35 nations partici [...]

    Read more

  • ITER Talks | All about ITER and fusion

    Beginning this autumn, the ITER Organization will be launching a new video series to inform, inspire and educate. The first video—introducing the series and off [...]

    Read more

  • Image of the week | A majestic components enters the stage

    The floor of the Assembly Hall is an ever-changing stage. Like characters in a grand production, components of all size and shapes make a spectacular entry, pl [...]

    Read more

  • Magnet system | A set of spares for the long journey

    In about five years, ITER will embark on a long journey through largely uncharted territory. Conditions will be harsh and—despite all the calculations, modellin [...]

    Read more

Of Interest

See archived entries

The physics behind the transition to H-mode

PPPL physicists Seung-Hoe Ku, Robert Hager, Choong-Seock Chang, and Randy Michael Churchill. (Photo by Elle Starkman) (Click to view larger version...)
PPPL physicists Seung-Hoe Ku, Robert Hager, Choong-Seock Chang, and Randy Michael Churchill. (Photo by Elle Starkman)
H‐mode—or the sudden improvement of plasma confinement in the magnetic field of tokamaks by approximately a factor of two—is the high confinement regime that all modern tokamaks, including ITER, rely on.

It was observed for the first time rather by accident (read more here) and to this day the physics behind H-mode remains not fully understood.

Scientists at the Princeton Plasma Physics Laboratory (PPPL) in the US have made a step in the direction of elucidating the phenomenon by simulating, for the first time, the spontaneous transition of turbulence at the edge of a fusion plasma to H-mode.
The research was achieved with the extreme-scale plasma turbulence code XGC developed at PPPL in collaboration with a nationwide team. This massively parallel simulation, which reveals the physics behind the transition, utilized most of a supercomputer's power—running for three days and using 90 percent of the capacity of Titan at the Oak Ridge Leadership Computing Facility (the most powerful supercomputer for open science in the US).

"After 35 years, the fundamental physics of the bifurcation of turbulence into H-mode has now been simulated, thanks to the rapid development of the computational hardware and software capability," said C.S. Chang, first author of the April Physical Review Letters paper [118, 175001 (2017)] that reported the findings. Co-authors included a team from PPPL, the University of California, San Diego, and the MIT Plasma Science and Fusion Center. Seung-Hoe Ku of PPPL performed the simulation.

Read the full report by John Greenwald on the PPPL website.



return to the latest published articles