Some scientists believe that controlled nuclear fusion is the "holy grail" of clean energy production, because of the potential to create a limitless source of clean energy from it.

However, while the process of nuclear fusion fuels the Sun and other stars, the concept is still only a dream for people on Earth. There are still several barriers that hinder experts from making it possible.

But not for long, scientists say.

An international group of researchers has taken a few steps closer to the dream by developing a method that could "see" where energy goes during a process called fast ignition, a tactic to trigger nuclear fusion reactions using a high-powered laser.

Led by engineers from the University of California, San Diego and General Atomics, the team's energy flow visualization technique could allow scientists to test various ways to improve energy delivery to the fuel target in experiments.

Overcoming The Major Hurdle

To start a nuclear fusion, the process of fast ignition undergoes two stages. First, hundreds of lasers push the fusion fuel to high density. The fusion fuel is a combination of tritium and deuterium enclosed within a round plastic fuel capsule.

After that, a high-powered laser ignites the compressed fuel.

Fast ignition is a promising step toward controlled nuclear fusion as it needs less energy than other approaches, researchers said.

However, for fast ignition to be successful, scientists have to jump over a giant hurdle: how to direct energy from the high-intensity laser into the densest region of the fusion fuel.

"This has been a major research challenge since the idea of fast ignition was proposed," said Professor Farhat Beg, a mechanical and aerospace engineering expert and the director of UCSD's Center for Energy Research.

And the solution is a breakthrough. The team devised a way to see where energy travels when the high-powered laser strikes the fusion fuel. The method depends on the use of copper tracers inside the plastic fuel capsule. When the laser beam is targeted at the compressed fuel, it produces electrons with high-energy that hit the copper tracers and cause them to emit X-rays that scientists can then image.

Christopher McGuffey, co-author of the paper, which is featured in the journal Nature Physics, said that before they created the technique, it was as if they were looking in the dark.

"Now, we can better understand where energy is being deposited so we can investigate new experimental designs to improve delivery of energy to the fuel," he added. The team hopes to perform future attempts to improve fast ignition.

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