In a significant stride toward advancing fusion energy technology, researchers at the Plasma Research Center of the University of Tsukuba in Japan have developed groundbreaking gyrotrons that could revolutionize the way we approach low-magnetic field fusion devices. The study, published in the journal “Published in the journal ‘Nuclear Fusion’,” details the creation of a 14 GHz 1 MW gyrotron and a 28 GHz 0.4 MW continuous wave gyrotron, both of which hold immense potential for enhancing electron Bernstein wave heating, electron cyclotron heating, and electron cyclotron current drive experiments.
Gyrotrons are high-power microwave tubes that are crucial for heating plasmas in fusion devices. The newly developed 14 GHz gyrotron, designed by lead author T. Kariya and his team, incorporates a novel approach of direct RF beam coupling through a built-in corrugated waveguide. This innovation minimizes the RF transmission path and significantly boosts transmission efficiency. In initial tests, the gyrotron achieved an impressive output power of 1.05 MW with a pulse width of 2 ms at 14.018 GHz, marking the first instance of such high power output in the 14 GHz range.
“This achievement represents a major milestone in the development of gyrotrons for fusion applications,” said Kariya. “The direct RF beam coupling technique not only enhances efficiency but also paves the way for more compact and cost-effective fusion devices.”
The study also highlights the development of a 28 GHz 0.4 MW continuous wave gyrotron, specifically designed for the Q-shu University Experiments with Steady-state Spherical Tokamak. This gyrotron employs a double-disk sapphire window and a depressed collector, which are critical components for achieving high-power, continuous wave operation. Experimental results demonstrated a maximum power of 1.24 MW with a pulse width of 2 ms, as well as a maximum total efficiency with a collector potential depression of 53.1% and an output power of 0.52 MW with a pulse width of 8 ms.
Furthermore, the researchers utilized a 28/35 GHz dual-frequency gyrotron to evaluate the cooling performance of the double-disk sapphire window. By comparing experimental data with simulation results, they confirmed the feasibility of achieving 0.4 MW continuous wave operation at 28 GHz. This breakthrough is expected to have significant implications for the energy sector, particularly in the development of more efficient and sustainable fusion power plants.
The commercial impact of this research is substantial. Gyrotrons are essential components in the plasma heating systems of fusion reactors, and the advancements made by Kariya and his team could lead to more efficient and cost-effective fusion energy solutions. As the world continues to seek cleaner and more sustainable energy sources, the development of high-power, low-frequency gyrotrons represents a crucial step forward in the quest for practical fusion power.
“This research not only advances our understanding of gyrotron technology but also brings us closer to realizing the full potential of fusion energy,” said Kariya. “The applications of these gyrotrons extend beyond fusion devices, offering new possibilities for industrial and medical applications as well.”
As the energy sector continues to evolve, the innovations presented in this study are poised to shape the future of fusion technology, driving us toward a more sustainable and energy-efficient future. The work of Kariya and his team at the Plasma Research Center of the University of Tsukuba serves as a testament to the power of scientific inquiry and its potential to transform the energy landscape.