近日，美国激光能量学实验室的V. Gopalaswamy及其研究团队取得一项新进展。经过不懈努力，他们成功演示直接驱动惯性约束聚变中流体力学等效燃烧等离子体。相关研究成果已于2024年2月5日在国际知名学术期刊《自然—物理学》上发表。

该研究团队报道了OMEGA激光系统实验结果的流体力学等效定标，并表明当等离子体的中心部分(热点)的尺寸缩放至少为3.9±0.10倍时，这些已经达到了燃烧等离子体的核心条件，且需要至少1.7±0.13MJ的驱动激光能量。此外，研究人员将结果按国家点火装置提供的2.15MJ激光能量进行氢当量缩放，发现这些内爆达到了点火所需劳森参数的86%。这项研究结果支持直接驱动惯性约束聚变作为实现热核点火和激光聚变净能量的可靠方法。

据悉，将激光聚焦在一个充满氘和氚的小靶表面上，使其发生内爆，从而产生一个热而致密的等离子体，在这个等离子体中发生热核聚变反应。为了使等离子体能够自我维持，等离子体的加热必须由聚变反应提供的能量主导——这种情况被称为燃烧等离子体。一个度量是广义劳森参数，其值高于0.8左右意味着等离子体在燃烧。

附：英文原文

Title: Demonstration of a hydrodynamically equivalent burning plasma in direct-drive inertial confinement fusion

Author: Gopalaswamy, V., Williams, C. A., Betti, R., Patel, D., Knauer, J. P., Lees, A., Cao, D., Campbell, E. M., Farmakis, P., Ejaz, R., Anderson, K. S., Epstein, R., Carroll-Nellenbeck, J., Igumenshchev, I. V., Marozas, J. A., Radha, P. B., Solodov, A. A., Thomas, C. A., Woo, K. M., Collins, T. J. B., Hu, S. X., Scullin, W., Turnbull, D., Goncharov, V. N., Churnetski, K., Forrest, C. J., Glebov, V. Yu., Heuer, P. V., McClow, H., Shah, R. C., Stoeckl, C., Theobald, W., Edgell, D. H., Ivancic, S., Rosenberg, M. J., Regan, S. P., Bredesen, D., Fella, C., Koch, M., Janezic, R. T., Bonino, M. J., Harding, D. R., Bauer, K. A., Sampat, S., Waxer, L. J., Labuzeta, M., Morse, S. F. B., Gatu-Johnson, M., Petrasso, R. D., Frenje, J. A., Murray, J., Serrato, B., Guzman, D., Shuldberg, C., Farrell, M., Deeney, C.

Issue&Volume: 2024-02-05

Abstract: Focussing laser light onto the surface of a small target filled with deuterium and tritium implodes it and leads to the creation of a hot and dense plasma, in which thermonuclear fusion reactions occur. In order for the plasma to become self-sustaining, the heating of the plasma must be dominated by the energy provided by the fusion reactions—a condition known as a burning plasma. A metric for this is the generalized Lawson parameter, where values above around 0.8 imply a burning plasma. Here, we report on hydro-equivalent scaling of experimental results on the OMEGA laser system and show that these have achieved core conditions that reach a burning plasma when the central part of the plasma, the hotspot, is scaled in size by at least a factor of 3.9±0.10, which would require a driver laser energy of at least 1.7±0.13MJ. In addition, we hydro-equivalently scale the results to the 2.15MJ of laser energy available at the National Ignition Facility and find that these implosions reach 86% of the Lawson parameter required for ignition. Our results support direct-drive inertial confinement fusion as a credible approach for achieving thermonuclear ignition and net energy in laser fusion.

DOI: 10.1038/s41567-023-02361-4

Source: https://www.nature.com/articles/s41567-023-02361-4