Nature2014-06-26 1:49 PM

惯性约束聚变研究的新进展 Fuel gain exceeding unity in an inertially confined fusion implosion

论文摘要 

将核聚变作为一个可行替代能源来开发的工作还在继续,但进展一直缓慢。惯性约束聚变(在其中一个燃料靶标被压缩和加热来引发核聚变)的一个关键实验目标是,达到诱导的聚变反应所产生的能量超过在压缩/加热过程中沉积到燃料内的能量这样一个阶段。现在,这一临界点(使“燃料增益”大于一)已在位于美国加州利弗莫尔的“国家点火装置”达到。他们采用192个激光束来将一个燃料芯块加热和压缩到核聚变反应能够发生的程度,获得了比以前大10倍的能量产出。然而,要使聚变能产出超过压缩燃料芯块所需的总能量,还将需要取得进一步的进展。

Abstract 

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.

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