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At its seventeenth meeting in November 2015, the ITER Council named Won Namkung, from Korea, to succeed Robert Iotti as Chair effective 1 January 2016.
Dr Namkung is a Professor Emeritus of Physics at Pohang University of Science and Technology (POSTECH) in southwest Korea and Executive Adviser at the Pohang Accelerator Laboratory.
In the course of his career, he contributed to the construction of KSTAR, Korea's first all-superconducting tokamak. He has also been involved in Korea's contribution to ITER, serving as the project's first Management Assessor.
Dr Namkung received his BS in Physics from Seoul National University and his PhD in Physics from University of Tennessee.
Robert Iotti, from the US, finishes his two-year term as Council Chair on 31 December 2015.
A team of physicists led by Stephen Jardin of the US Department of Energy's Princeton Plasma Physics Laboratory (PPPL) has discovered a mechanism that prevents the electrical current flowing through fusion plasma from repeatedly peaking and crashing.
This behaviour, known as a "sawtooth cycle," can cause instabilities within the plasma's core.
The team, which included scientists from General Atomics (San Diego) and the Max Planck Institute for Plasma Physics (Germany), performed calculations on the Edison computer at the National Energy Research Scientific Computing Center, a division of the Lawrence Berkeley National Laboratory. Using M3D-C1, a program they developed that creates three-dimensional simulations of fusion plasmas, the team found that under certain conditions a helix-shaped whirlpool of plasma forms around the centre of the tokamak. The swirling plasma acts like a dynamo—a moving fluid that creates electric and magnetic fields.
Together these fields prevent the current flowing through plasma from peaking and crashing.
The researchers found two specific conditions under which the plasma behaves like a dynamo. First, the magnetic lines that circle the plasma must rotate exactly once, both the long way and the short way around the doughnut-shaped configuration, so an electron or ion following a magnetic field line would end up exactly where it began. Second, the pressure in the centre of the plasma must be significantly greater than at the edge, creating a gradient between the two sections. This gradient combines with the rotating magnetic field lines to create spinning rolls of plasma that swirl around the tokamak and gives rise to the dynamo that maintains equilibrium and produces stability.
Image: A cross-section of the virtual plasma showing where the magnetic field lines intersect the plane. The central section has field lines that rotate exactly once. (Credit: Stephen Jardin)