中国“人造太阳”实验传新进展

Core Viewpoint - The research team from the Hefei Institutes of Physical Science has confirmed the existence of a density-free zone in the EAST (Experimental Advanced Superconducting Tokamak), providing significant physical evidence for high-density operation in magnetic confinement nuclear fusion devices [1][5]. Group 1: Research Findings - The tokamak device utilizes magnetic confinement to achieve controlled nuclear fusion, with plasma density being a critical parameter that directly affects fusion reaction rates [2][3]. - Previous research indicated a density limit for plasma, beyond which the plasma would break and escape magnetic confinement, releasing significant energy and impacting the device's safe operation [2][3]. - The team developed a boundary plasma-wall interaction self-organization (PWSO) theoretical model, identifying the key role of radiation instability caused by boundary impurities in triggering the density limit [5]. Group 2: Experimental Methods and Results - By utilizing a fully metallic wall environment in EAST, researchers employed methods such as electron cyclotron resonance heating and pre-filling gas to reduce boundary impurity sputtering, effectively delaying the onset of the density limit and plasma disruption [5]. - The physical conditions of the target plate were adjusted to reduce tungsten impurity-induced sputtering, allowing the plasma to surpass the density limit and enter a new density-free zone [5]. - The experimental results were found to be highly consistent with the PWSO theoretical predictions, marking the first confirmation of the existence of a tokamak density-free zone [5].