ABSTRACT
Mastering nuclear fusion, which is an abundant, safe, and environmentally competitive energy, is a great challenge for humanity. Tokamak represents one of the most promising paths toward controlled fusion. Obtaining a high-performance, steady-state, and long-pulse plasma regime remains a critical issue. Recently, a big breakthrough in steady-state operation was made on the Experimental Advanced Superconducting Tokamak (EAST). A steady-state plasma with a world-record pulse length of 1056 s was obtained, where the density and the divertor peak heat flux were well controlled, with no core impurity accumulation, and a new high-confinement and self-organizing regime (Super I-mode = I-mode + e-ITB) was discovered and demonstrated. These achievements contribute to the integration of fusion plasma technology and physics, which is essential to operate next-step devices.
ABSTRACT
Mass injection has found new applications in magnetic fusion including edge-localized-mode control. Better understanding of injected-mass-plasma interactions requires spatially and temporally resolved diagnostics that can characterize the dynamics of the mass interactions with plasmas. Fast imaging can be used to characterize the ionization dynamics such as the propagation of the ionization front, which moves at the thermal sound or higher speed, and mixing of the neutral atoms with the ambient plasma. Multi-wavelength spectral imaging is promising since different parts of the plasma give different spectral signatures. Here we describe a dual-spectral imaging technique based on a monochromatic camera sensor and filters with two passing optical wavelengths. The method is shown to improve image contrast, and it compares favorably with alternatives such as color cameras and methods using a filter wheel. Further improvements through relative filter area ratios and plenoptic imaging are possible. The initial results from EAST and plenoptic imaging are also included.
