Hefei Research Institute made progress in improving high-density and low-clutter current drive capability

Recently, researchers from the Low Clutter Research Group of the Institute of Plasma Physics of the Hefei Institute of Material Science, Chinese Academy of Sciences have made new progress in improving the driving ability of high-density and low-clutter currents. The relevant research results were published by researchers Ding Bojiang and Dr. Li Miaohui. Field Journal on Nuclear Fusion on 'Nucl. Fusion 58 (2018) 095003; Nucl. Fusion 58 (2018) 126015'.

The low-clutter current drive efficiency drop at high density is a challenge in the field of low-clutter current drive research and a key factor limiting its application to ITER and future reactors. To explore low clutter in future fusion reactors In recent years, researchers in the research team have used two sets of high-power low-clutter systems with different frequencies on EAST to carry out related research. The results show that 'Nucl. Fusion 58 (2018) 095003': edge plasma parameters and low clutter Frequency is an important factor affecting the driving of low clutter current. By increasing the frequency of the wave source, reducing the boundary backflow and increasing the temperature of the boundary electrons, weakening the decay behavior of low clutter parameters and reducing the collision absorption of wave power at the edge, thereby increasing the low density and low density. Clutter current drive capability. Further research indicates that 'Nucl. Fusion 58 (2018) 126015': The difference in driving power of low-frequency currents at different frequencies increases with increasing plasma density (Table 1), and the difference from the decay behavior of the parameters The change in plasma density is consistent (Fig. 1), further demonstrating the effect of parametric decay on low clutter current drive; Correlation between plasma edge current distribution and low clutter parameter decay (Fig. 1, 2) (parametric decay is strong, edge drive current share is large: the wavelet generated by the parametric decay process has a higher parallel refractive index (N/) /), deposited in a relatively outer region, resulting in relatively high edge currents, provides a possible new method for improving the edge current distribution and improving plasma confinement with low clutter; nonlinear simulation results (Figure 3) indicate As the density increases, the parametric decay-driven mode growth rate increases, but the 4.6 GHz growth rate is significantly less than 2.45 GHz, qualitatively explaining the experimental results.

The above work has been assisted by the various systems of the plasma, and also benefited from the cooperation of international counterparts, especially the joint research of Italian ENEA, French CEA and American MIT collaborators, and obtained national key research and development projects, National Magnetic Restricted Nuclear Specialized research on fusion energy development, National Natural Science Foundation of China, Hefei Science Center of the Chinese Academy of Sciences, 'High-end User Development Fund' and Wang Kuancheng Education Fund.

Table 1. Differences between ring voltage and fast electron radiation for two frequencies at different density conditions

Figure 1. Measurement of two-frequency low-clutter parameter decay under different density conditions

Figure 2. Effect of wave source frequency (a) and plasma density (b) on boundary current distribution

Figure 3. Spectrum calculation results for mode growth rates at different boundary densities