Inertially confined plasma in an imploding bubble
Inertially confined plasma in an imploding bubble
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DOI：
10.1038/nphys1701
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发表时间：
2010-08-01
期刊：
影响因子：
19.6
通讯作者：
Suslick, Kenneth S.
中科院分区：
文献类型：
--
作者：
Flannigan, David J.;Suslick, Kenneth S.
空化液体中球形超音速气泡内爆的模型预测，它可以产生足以驱动热核聚变的温度和密度（1，2）。聚变的令人信服的证据尚未显示，但声空化产生的瞬态条件肯定是极端的（3-5）。然而，关于泡沫破裂过程中所产生的条件的可观测数据非常缺乏。直到最近才获得了等离子体形成的有力证据（6）。在这里，我们确定的等离子体电子密度，离子加宽参数和电离度在单泡声致发光作为声驱动压力的函数。我们发现，电子密度可以控制在四个数量级以上，超过10（21）cm（-3）-与激光驱动聚变实验中产生的密度相当（7）-有效等离子体温度范围从7，000到超过16，000 K。在最高的声学驱动力，我们发现，中性Ar发射线不再提供一个准确的测量等离子体中的条件。通过占的时间分布的声致发光脉冲和潜在的光学不透明度的等离子体，我们的研究结果表明，最终的条件内产生一个崩溃的气泡可能远远超过那些确定从发光体积的透明外部区域的发射。
Models of spherical supersonic bubble implosion in cavitating liquids predict that it could generate temperatures and densities sufficient to drive thermonuclear fusion(1,2). Convincing evidence for fusion is yet to be shown, but the transient conditions generated by acoustic cavitation are certainly extreme(3-5). There is, however, a remarkable lack of observable data on the conditions created during bubble collapse. Only recently has strong evidence of plasma formation been obtained(6). Here we determine the plasma electron density, ion-broadening parameter and degree of ionization during single-bubble sono-luminescence as a function of acoustic driving pressure. We find that the electron density can be controlled over four orders of magnitude and exceed 10(21) cm(-3)-comparable to the densities produced in laser-driven fusion experiments(7)-with effective plasma temperatures ranging from 7,000 to more than 16,000 K. At the highest acoustic driving force, we find that neutral Ar emission lines no longer provide an accurate measure of the conditions in the plasma. By accounting for the temporal profile of the sonoluminescence pulse and the potential optical opacity of the plasma, our results suggest that the ultimate conditions generated inside a collapsing bubble may far exceed those determined from emission from the transparent outer region of the light-emitting volume.