In the heart of Japan, at the National Institutes for Quantum and Radiological Science and Technology in Ibaraki, a groundbreaking study has just been published, shedding new light on the inner workings of the world’s largest operating tokamak, JT-60SA. Led by Dr. Satoshi Inoue, the research delves into the intricacies of diamagnetic energy measurements, offering fresh insights into the evaluation of poloidal beta and internal inductance. These parameters are crucial for understanding and optimizing plasma behavior, a key step in harnessing the power of nuclear fusion.
The study, published in the journal Nuclear Fusion, focuses on the first operational phase of JT-60SA, where diamagnetic measurements were used to assess critical plasma equilibrium parameters. The results are nothing short of impressive. The stored energy evaluated during these measurements exceeded 200 kJ with just 1 MJ of electron cyclotron heating. This is a significant milestone, as it demonstrates the efficiency of the tokamak in maintaining and utilizing energy within the plasma.
One of the most intriguing findings is the behavior of internal inductance ($l_\mathrm i$). During the plasma current ramp-down phase, $l_\mathrm i$ was observed to rise from around unity to above 2. This phenomenon, which was successfully captured by the diamagnetic measurements, provides valuable data for understanding plasma stability and confinement. “The rise in $l_\mathrm i$ is a critical indicator of plasma behavior,” Dr. Inoue explains. “It helps us understand how the plasma is evolving and how we can better control it to achieve sustained fusion reactions.”
The research also addresses the challenges posed by the interaction between diamagnetic measurements and superconducting coils. The team developed methods to correct errors arising from this interaction, ensuring the accuracy of their measurements. “The correction of these errors is crucial for the reliability of our data,” Dr. Inoue notes. “It allows us to make more precise evaluations of the plasma parameters, which is essential for advancing fusion research.”
The implications of this research extend far beyond the laboratory. As the world seeks sustainable and clean energy sources, nuclear fusion stands out as a promising candidate. The insights gained from this study could pave the way for more efficient and stable fusion reactors, bringing us one step closer to commercial fusion power. The ability to accurately measure and control plasma parameters is a cornerstone of this endeavor, and the work done by Dr. Inoue and his team at the National Institutes for Quantum and Radiological Science and Technology is a significant contribution to this field.
The study, published in Nuclear Fusion, not only advances our understanding of plasma behavior but also sets a benchmark for future research. As we continue to push the boundaries of fusion technology, the lessons learned from JT-60SA will be invaluable. The journey to commercial fusion power is long and fraught with challenges, but with each breakthrough, we inch closer to a future where clean, abundant energy is a reality.
