A journey inspired by nature
First Light’s journey to a new method for fusion started in nature, with the pistol shrimp. The pistol shrimp has an oversized claw, which it can “click” shut at very high speed. The motion is so fast that it launches a shock wave into the water and stresses it so much that it rips apart and forms a bubble. The shock wave and the bubble interact and the bubble collapses just as quickly as it forms. The vapour inside is heated to tens of thousands of degrees and emits a bright flash of light.
Tens of thousands of degrees sounds impressive, but fusion needs tens of millions. First Light grew out of simulation work looking at shock-driven cavity collapse, asking whether this phenomenon can reach conditions for fusion. And instead of the shrimp’s claw, we use a rather bigger and faster hammer, a high-velocity projectile.
The target design is the key technology
Our targets now have two aspects, the amplifier and the fuel capsule. The amplifier does two things. First, it boosts the pressure of impact. The original concept, a shockwave collapsing one cavity by itself, shows one way this amplification can happen. When the cavity collapses, it forms a jet, which crosses the cavity and hits into the rear wall. The resulting pressure is higher than the pressure of the original input shock.
The targets are the key technology in First Light’s approach to fusion and they are nearly all trade secrets. One example uses three cavities, two big and one small. The collapse of the two bigger cavities focuses the pressure onto the small one in between, which is collapsed with a higher pressure and from two sides rather than one.
Comparing our target design to other fusion approaches using the triple product shows the unique space that First Light occupies. Our targets achieve very high values of the density-time product and span a previously unexplored parameter space. To reach gain, we need to increase the temperature, and the principal way to do this is to increase the projectile velocity.
Agnostic driver
Whilst we believe that a projectile system offers the best path to cost-competitive power production, this is not the only path available to us. Any system able to produce the required pressure on one side of the target could be used as an alternative. A high-energy laser, for example, would be able to do this. If laser costs were to fall substantially, First Light could benefit by developing an additional driver option using such a laser with our advanced target designs. The benefits of our simpler plant concept would remain the same, and the target design would still be the key enabling technology to make one-sided drive work.