In a significant stride toward advancing fusion energy technology, researchers have successfully conducted boronization on the Experimental Advanced Superconducting Tokamak (EAST) in China, featuring an ITER-like tungsten divertor and a fully metallic first wall. This breakthrough, detailed in a study published in the journal *Nuclear Fusion* (translated from the original title), could have profound implications for the future of fusion energy, particularly in enhancing plasma performance and reducing impurity radiation.
The research, led by Dr. Y.H. Guan from the University of Science and Technology of China and the Institute of Plasma Physics at the Chinese Academy of Sciences, marks a pivotal moment in the quest for sustainable fusion energy. Boronization, a process involving the application of boron to the walls of a fusion device, has long been recognized for its potential to improve plasma performance. However, the recent application of this technique on EAST, assisted by ion cyclotron wall conditioning (ICWC), has yielded remarkable results.
“Boronization has been a game-changer for us,” said Dr. Guan. “The process not only enhanced the stored energy in the plasma but also significantly improved confinement performance. This is a crucial step forward in our efforts to make fusion energy a viable option for the future.”
The study revealed that after a single boronization session using 12 grams of carborane, a boron-rich compound, a film of approximately 120 nanometers was deposited on the EAST walls. This thin layer of boron led to a substantial release of hydrogen during initial plasma discharges, which initially caused some challenges in controlling the divertor neutral pressure and plasma density. However, as the plasma operations continued, the hydrogen-to-deuterium ratio gradually decreased, indicating a successful transition to a more stable plasma environment.
One of the most notable findings was the significant reduction in impurity radiation, particularly oxygen and heavy metals like tungsten, iron, and copper. This reduction led to a decrease in the effective ion charge, a measure of the plasma’s impurity content, from 2.3 to 2.0. Consequently, the stored energy in the plasma increased by about 20%, and the line-integrated radiation profile in the plasma core decreased by nearly 35%.
“The reduction in impurity radiation is a critical achievement,” explained Dr. Guan. “It not only improves the overall performance of the plasma but also extends the lifetime of the boronization coating. This is essential for the long-term viability of fusion reactors.”
The enhanced wall fueling and reduced impurity radiation also led to increases in plasma density and electron temperature by approximately 7% and 12%, respectively. The lifetime of the boronization coating was evaluated to be about 1700 seconds of deuterium plasma, with a cumulative injected energy of 2125 MJ on EAST.
The implications of this research extend beyond the immediate improvements in plasma performance. The successful application of ICWC-boronization on EAST provides valuable insights for the development of future fusion devices, including the international ITER project, which aims to demonstrate the feasibility of fusion power on a commercial scale.
As the world continues to seek sustainable and clean energy solutions, advancements in fusion technology are more critical than ever. The work of Dr. Guan and his team represents a significant step forward in this endeavor, offering hope for a future powered by fusion energy.
“This research is a testament to the power of international collaboration and the relentless pursuit of scientific advancement,” said Dr. Guan. “We are excited about the potential of boronization and ICWC to shape the future of fusion energy and contribute to a more sustainable world.”