Innovation Winter 2024.25

FEATURE

Claire Preston, a project manager specializing in diagnostics and electrical engineering, demonstrates the visual diagnostic techniques used for the latest prototypes.

Engineering challenges for fusion conditions Nuclear fusion occurs when two atoms are pulled together very closely – on the order of a quadrillionth of a metre. When this happens, atomic nuclei attract each other and pull into a single, larger nucleus, causing a burst of energy to be released. However, in a phenomenon called electrostatic repulsion, atomic electric fields repel against each other to prevent the atoms from becoming that close. Fusion requires exceptionally high amounts of energy to overcome repulsion and trigger the combination since the atoms need to move fast enough before electrostatic repulsion takes hold. Researchers have sought to lower the activation energy of this reaction by using heavier versions of hydrogen that have more neutrons, doubling or tripling the weight of the

atoms. The most established combination is between two- neutron deuterium, a common isotope that can be easily distilled from seawater, and three-neutron tritium, an extremely rare isotope of hydrogen worth over $40,000 per gram. As Mike Donaldson, P.Eng., senior vice president of technology development at General Fusion, puts it, “Deuterium-tritium combinations are the easiest hard reaction to do.” Donaldson’s team has committed to using the costly isotope combination, along with most major fusion companies. But even with the aid of these isotopes, hydrogen fusion reactors on Earth require 10 kiloelectron volts (keV), an energy level corresponding to the average energy of particles heated to 100 million degrees Celsius. Many fusion organizations have different ways of attempting the high levels of heat required. The most

24

Winter 2024/25

Innovation