Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Nature. 2014 Feb 20;506(7488):343-8. doi: 10.1038/nature13008. Epub 2014 Feb 12.
Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium-tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a 'high-foot' implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite.
点火是实现聚变能成为可行的替代能源的关键，但目前尚未实现。实现点火的关键步骤之一是，通过惯性约束聚变等离子体中的聚变反应产生的能量超过在内爆过程中沉积到氘-氚聚变燃料和热点中的能量，从而实现大于 1 的燃料增益。在这里，我们报告了在美国国家点火装置上使用“高足”内爆方法实现聚变燃料增益超过 1 的成就，这是一种操纵激光脉冲形状的方法，可以减少内爆过程中的不稳定性。这些实验表明，与过去的氘-氚内爆实验相比，产率性能有了一个数量级的提高。我们还看到了α粒子自加热对产率的显著贡献，以及为加速氘-氚聚变燃烧最终“失控”并点燃所需的“自举”的证据。
