Researchers in Germany have developed a new computational method that could significantly speed up experiments at the world’s most powerful X-ray laser, and potentially advance fusion energy research.

Created by scientists at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the new method can reportedly accelerate complex computer simulations used to analyze X-ray scattering experiments at the European XFEL.

According to the research team, the method can make these simulations run up to 50 times faster while preserving critical physical detail. The achievement is set to facilitate substantial progress in fusion research and laboratory astrophysics.

Tobias Dornheim, PhD, head of the high-energy density department at HZDR’s Institute of Radiation Physics, stressed its importance. “If we want to have a fusion power plant, we have to understand what really happens in such extreme states of matter,” he said. “Now, our new method makes it possible to comprehensively and precisely analyze the datasets from such experiments.”

Faster simulations unlocked

Scientists use facilities such as the European XFEL, near Hamburg, to study matter under extreme temperatures and pressures similar to those found inside stars and giant planets. The same conditions can also be produced in the lab, in laser fusion experiments.

To better understand what happens under these extreme conditions, researchers use X-ray scattering. They fire intense X-ray beams through samples and analyze how the beams scatter and infer properties such as density and temperature.

But interpreting those experiments requires massive computer simulations, which are extremely computationally expensive. “We simulate the system with various parameters and look to see which combination corresponds to the experimental observation,” Dornheim pointed out.

At high temperatures, scientists must consider many quantum mechanical states, and also deal with numerical artifacts that can distort the results. To interpret their experiments, they have to calculate numerous combinations of temperature and density (parameter scan), which requires a lot of computing time. “And we simply don’t have unlimited amounts of that,” Dornheim added.

A new computational tool

To tackle the issue, the HZDR team built a method that can identify which parts of the simulated signal contain real physical information, and, by contrast, which are merely numerical noise. It reportedly relies on a mathematical transformation into imaginary time, a quantum mechanical concept closely related to temperature.

Zhandos Moldabekov, PhD, a researcher at HZDR who came up with the idea for the method, said the method preserves the signal’s physical structure. “Building on this, we combine a reliable convergence test with a filtering procedure that removes artificial ringing without distorting the physical information,” he stated.

“In our tests, the simulations ran 50 times faster,” Moldabekov explained, adding that this means scientists will be able to run more simulations, as well as analyze experimental data more accurately. The method is expected to play a major role in experiments at the European XFEL, especially within the HIBEF consortium.

It could also advance laboratory astrophysics by helping researchers recreate the extreme pressures and temperatures inside planets. What’s more, it could allow them to calculate material properties, like electrical conductivity and radiation absorption, more quickly and accurately.

“It should be possible to develop our method into a standard tool for interpreting modern X-ray experiments,” Moldabekov concluded in a press statement. “In the future, it could play a central role in exploring extreme states of matter.”

The study has been published in the journal npj Computational Materials.