Find the "artificial sun" high-performance steady-state operating mode

The reporter learned from the Institute of Plasma Physics of the Chinese Academy of Sciences that the EAST superconducting tokamak team developed a high-performance steady-state plasma operation mode based on the preliminary work and systematically verified its operation with future fusion reactors. Conditional compatibility. The research results were published online recently in the international physical journal "Physical Review Letters".

In the Tokamak nuclear fusion experimental device, the boundary region of the highly confined plasma periodically bursts into an instability called boundary local mode (ELM). The large-scale ELM is similar to the solar flare burst, causing the instantaneous release of plasma energy and particles, ejecting powerful thermal pulses, eroding the inner wall of the device, and even causing the melting of the material, and generating a large number of impurity particles to contaminate the fusion core plasma The fusion reactor operates in a steady state for a long time.

In the future fusion reactor, the transient thermal load caused by ELM needs to be reduced by at least 20 times. This is a serious challenge facing the international thermonuclear fusion reactor ITER. Exploring the high-constrained operation mode without ELM or with small amplitude ELM and Its physical mechanism is a major scientific frontier issue in the research of magnetic confinement fusion.

Grassy ELM is a special spontaneous high-frequency small-amplitude ELM. The transient thermal load it brings is usually lower than 1/20 of the conventional large-scale ELM, but its mechanism and acquisition conditions are unclear. It has been difficult to obtain this operating mode stably. In the future fusion reactor, whether this operation mode can be obtained stably and reliably is an urgent question to be answered by the international fusion community.

The EAST team confirmed the physical conditions for obtaining this model under physical conditions such as metal walls, low rotation, and electron-led heating similar to the future fusion reactor. For the first time in their experiments, they revealed the inherent kinetic mechanism of the formation of Grassy ELM, and found that it has a strong ability to discharge impurities, which is particularly suitable for long-term steady-state operation of high-performance plasmas. This mode of operation provides a potential new solution for solving the transient thermal load bottleneck problem of fusion reactors and realizing the steady-state operation of fusion reactors.

It is reported that China is carrying out the integrated engineering design of the fusion engineering experimental reactor CFETR of 1GW fusion power. The normalized parameters of the plasma part of this operating mode are close to the design parameters of CFETR. The model laid the physical foundation. (Reporter Wu Changfeng)