We know how the \u00a0sun\u00a0 works. Another thing is to \u00a0imitate\u00a0 it. If we managed to build a \u00a0nuclear fusion reactor\u00a0, we would have \u00a0clean, safe\u00a0, and practically unlimited energy. But accomplishing this monumental task involves incredibly complex \u00a0engineering challenges\u00a0.<\/p>\n
<\/p>\n
One of the most colossal challenges in nuclear fusion is to build a \u00a0container\u00a0 that can withstand a \u00a0plasma\u00a0 hotter than the core of the sun. For years, scientists have experimented with various materials, ranging from \u00a0graphite\u00a0 to \u00a0high-resistance metals\u00a0 such as \u00a0tungsten\u00a0.<\/p>\n
<\/p>\n
A recent study<\/a> resulting from an \u00a0international collaboration\u00a0 among nine institutions confirms that we have a star candidate that works spectacularly well for the walls of these reactors: \u00a0lithium\u00a0.<\/p>\n <\/p>\n To understand why \u00a0lithium\u00a0 is so attractive, one must first visualize the chaos unleashed inside a \u00a0tokamak\u00a0, which is the most common fusion reactor design. A hydrogen gas, primarily its deuterium and tritium isotopes, is heated to over \u00a0100 million Celsius\u00a0 degrees until it becomes a plasma. Magnetic fields confine it potently, preventing contact with reactor walls. However, some particles inevitably escape and violently collide with the interior walls of the reactor.<\/p>\n <\/p>\n This is where lithium shines, as it can be utilized in a \u00a0liquid state\u00a0. Instead of eroding and degrading with each impact, it flows and heals itself instantly. This self-refreshing liquid layer protects the solid components behind it. Moreover, if the reactor walls are hot enough, lithium can form a \u00a0steam shield\u00a0 that absorbs much of the impact before it reaches the solid surface.<\/p>\n <\/p>\n Research shows that lithium isn’t just a passive shield but an active plasma conditioner. Instead of reflecting the fuel particles that escape, thus cooling the edge of the plasma and destabilizing it, lithium absorbs them. This helps \u00a0retain heat\u00a0 where it’s needed, thereby stabilizing the fusion reaction and enhancing plasma confinement.<\/p>\n <\/p>\n According to scientists, lithium is an encouraging candidate to replace graphite, which has a significantly higher erosion rate. When applied to tungsten walls, it enables fusion to operate at higher power densities, paving the path toward \u00a0more compact and efficient reactors\u00a0.<\/p>\n <\/p>\n Researchers tested two methods: first, to cover the lithium walls before initiating the plasma, and second, to inject \u00a0lithium powder\u00a0 directly into the plasma during reactor operation. The injection method yielded much better results in terms of creating a uniform and stable temperature profile\u2014one of the essential conditions for successful commercial fusion.<\/p>\n <\/p>\n All experiments took place at the \u00a0Tokamak DIII-D\u00a0 facility of General Atomics, funded by the \u00a0U.S. Department of Energy\u00a0. The study was published in the \u00a0Materials and Energy Nuclear Journal\u00a0 and involved researchers from the Princeton Plasma Physics Laboratory<\/a> and its collaborators.<\/p>\n <\/p>\n In addition to increasing pressure on the already stressed lithium market\u2014though scarce, it is not extracted at a pace that meets growing demand\u2014there is a more alarming issue. Lithium works *too well*. It captures \u00a0tritium\u00a0 with extremely high efficiency, preventing it from returning to the plasma as fuel.<\/p>\n <\/p>\n When tritium sticks to the walls, the reactor eventually runs out of fuel, and the cycle breaks down. The accumulation of \u00a0radioactive tritium\u00a0 in cold, hard-to-access areas of the reactor complicates maintenance and poses a safety risk. Worse still, this retention is greater when lithium is injected while the reactor is operational, which is the most effective method.<\/p>\n <\/p>\n The key to overcoming these issues is that experiments were conducted with lithium in \u00a0solid state\u00a0, at temperatures below its melting point. In a functional reactor with liquid lithium, a *dialysis system* might serve as a solution: Instead of allowing a continuous lithium flow to remain stagnant in the walls, it could be extracted, processed to separate the trapped tritium, and pumped back, clean and ready for use.<\/p>\n <\/p>\n This reactor design would have to be adapted to accommodate this new approach. It would require avoiding cold areas where lithium and tritium could accumulate, maintaining wall temperatures at higher and more controlled levels, and integrating a circuit for the extraction, processing, and reintroduction of lithium. While this material presents multiple solutions in our quest to replicate the sun, it also introduces new complexities.<\/p>\n <\/p>\n Image | General Atomics<\/p>\n In Xataka, there is an alternative to \u00a0nuclear fusion\u00a0. It is already underway and shows extraordinary promise.<\/p>\nA Self-Refreshing Shield<\/h2>\n
Goodbye to Graphite?<\/h2>\n
Two Ways to Apply Lithium<\/h2>\n
Challenges Ahead<\/h2>\n
A Possible Solution<\/h2>\n