"It's Solid but Hotter Than the Sun"... GIST Develops Technology to Create Extreme Materials [Reading Science]

Demonstrating the Potential to Reproduce Fusion Fuel and Planetary Interior Conditions

Achieving 99.1% Ion Beam Heating Efficiency and 0.55% Non-Uniformity

A research team at the Gwangju Institute of Science and Technology (GIST) has developed an ion beam design technology that can precisely recreate ultra-high temperature environments comparable to the surface of the sun, all while maintaining a solid state. This technology is considered a foundational step for more accurately reproducing fusion fuel conditions and the internal environments of giant planets in laboratory settings.

On May 13, GIST announced that Professor Woo-Seok Bang and his team from the Department of Physics and Optical Science had developed an 'inverse design' methodology. This approach involves first setting the desired thermal distribution and then inversely calculating the optimal ion beam energy distribution required to achieve it.

Virtual diagram of the solid heating process using an ion beam. Provided by the research team.

A high-energy ion beam is a type of particle beam produced by rapidly accelerating charged ions. Because it can deliver energy deep into materials, it is possible to heat a substance to an ultra-high temperature in an extremely short period of time.

The research team particularly focused on the fact that it is possible to achieve extreme states reaching tens of thousands of Kelvin (K) while maintaining the high density characteristic of solids. This corresponds to a "Warm Dense Matter (WDM)" state, which lies between solid and plasma phases. Such an environment is known to be similar to those found in fusion fuel and the interiors of giant planets like Jupiter.

Conventional ion beam heating methods have limitations due to the "Bragg Peak" phenomenon, where energy is concentrated at a specific depth, making it difficult to heat samples uniformly. Conversely, if the ion energy is set too high, the uniformity of heating improves, but a significant portion of ions simply pass through the sample, resulting in decreased energy efficiency.

The team used Monte Carlo simulations and calculations based on the Non-Negative Least Squares (NNLS) method to derive the optimal ion energy distribution that simultaneously achieves both uniformity and efficiency.

As a result, under super-exponential ion beam conditions with energy concentrated near 1 giga-electron volt (1 GeV), they achieved an energy transfer efficiency of 99.1% and a heating non-uniformity of 0.55%. Additionally, even under relatively simple quasi-monoenergetic ion beam conditions, they confirmed the potential for uniform heating with an efficiency of about 95% and a non-uniformity of 0.42%.

Research team photo. (From left) Woo-Seok Bang, Professor of Physics and Optical Science; Seong-Min Lee, Integrated Master's and Doctoral Student; Su-Ji Cho, Integrated Master's and Doctoral Student. Provided by GIST

The research team explained that by injecting a sufficient number of ions, it is possible to create ultra-high temperature states above 10,000 Kelvin (K), which is higher than the surface temperature of the sun (approximately 5,800 K). The entire heating process was analyzed to occur within 0.1 nanoseconds (ns).

This technology is expected to have applications not only in fusion fuel heating and high-energy-density physics research, but also in fields that require precise energy delivery to specific depths, such as particle beam cancer therapy.

Professor Bang stated, "This study demonstrates that it is possible to computationally design the optimal ion energy distribution required to achieve a desired heating profile," adding, "It can be widely applied in various research and application fields that require precise heating of materials in extreme states while maintaining solid density."

This research was supported by the Mid-Career Researcher Program of the Ministry of Science and ICT and the National Research Foundation of Korea. Seongmin Lee and Suji Jo, Integrated Master's and Doctoral Course Students in the Department of Physics and Optical Science at GIST, participated as co-first authors. The research findings were published online on April 19 in the international journal International Communications in Heat and Mass Transfer.

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