Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition
Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition
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DOI：
10.1038/35090525
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发表时间：
2001-08-23
期刊：
影响因子：
64.8
通讯作者：
Zepf, M
中科院分区：
文献类型：
--
作者：
Kodama, R;Norreys, PA;Zepf, M
现代高功率激光器可以产生与天体物理学（1），状态方程研究（2）和聚变能量研究（3，4）相关的极端物质状态。例如，球形聚合物壳的激光驱动内爆相对于固态实现了1,000倍的密度增加（5）。这些密度大到足以实现受控聚变，但是为了实现能量增益，必须将小体积的压缩燃料（称为“火花”）加热到约10（8）K的温度（对应于超过10 keV的热能）。在控制聚变的传统方法中，火花是由精确定时的冲击波产生和加热的，但这个过程需要精确的内爆对称性和非常大的驱动能量。原则上，这些要求可以通过分别执行压缩和快速加热而显著放宽（6-10）;然而，这种“快速点火器”方法（7）也具有缺点，例如传播损耗和超强激光脉冲被压缩燃料周围的等离子体偏转。在这里，我们采用了一种新的压缩几何形状，消除了这些问题，我们结合联合收割机生产的压缩物质在激光驱动的内爆皮秒快速加热的激光脉冲定时，以符合峰值压缩。因此，我们的方法允许同时进行有效的压缩和加热，为有效的聚变能生产提供了一条途径。
Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics(1), equation-of-state studies(2) and fusion energy research(3,4). Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state(5). These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 10(8) K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves(4), but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately(6-10); however, this 'fast ignitor' approach(7) also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.