Researchers can now image the flow of energy in nuclear fusion ignition attempts

It's fair to say that nuclear fusion is the holy grail of clean energy production, with the potential to provide limitless clean energy, but right now there are a fair few barriers to making it a reality. An international team of researchers has inched the dream one step closer to reality, creating a method by which energy dispersal can be observed during ignition attempts, paving the way for improved energy delivery during the process.

The breakthrough relates to a process known as fast ignition, which is one of the leading approaches focused on achieving controller nuclear fusion. A two-stage technique, it involves using hundreds of lasers to compress a small amount of fusion fuel (a mix of tritium and deuterium) inside a tiny spherical plastic fuel capsule, before employing a high-intensity laser to deliver a second burst of energy that ignites the fuel.

The process is promising, not least because it requires less energy than other approaches, but there are a number of problems that are currently stopping it from succeeding. One of these is the need to precisely direct the second stage laser so that it hits the densest region of the fuel.

This is where the new research steps in, providing a way to capture and analyze the dispersal of energy as the laser hits it target. To make that possible, the researchers integrated copper into the inside of the fuel capsule. When the laser beam hits the compressed fuel, high-energy electrons are generated. These hit the copper and cause X-ray emissions, which are then imaged to analyze the flow of energy.

With the knowledge that the imaging provides, scientists can now work on creating new techniques that will improve the delivery of energy to the compressed fuel target. The team has already made significant progress in that regard, trying out different experiment designs, eventually increasing the efficiency of energy delivery by a factor of four over previous tests.

"Before we developed this technique, it was as if we were looking in the dark," said paper co-author Christopher McGuffey. "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."

The team's findings were published in the journal Nature Physics.

Source: UC San Diego