Ultracold neutral plasma expansion in a strong uniform magnetic field
Ultracold neutral plasma expansion in a strong uniform magnetic field
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强均匀磁场中的超冷中性等离子体膨胀
DOI：
10.1103/physreve.105.045201
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发表时间：
2022
影响因子：
2.4
通讯作者：
Murillo, Michael S.
中科院分区：
文献类型：
--
作者：
Sprenkle, R. Tucker;Bergeson, S. D.;Silvestri, Luciano G.;Murillo, Michael S.
在强磁化的中性等离子体中，垂直于磁场方向的电子运动减小。这会改变等离子体的动态特性，如温度平衡、空间密度演化、电子压力、导热性和导电性。在本文中，我们报告了在强磁场存在下自由等离子体膨胀的测量结果。我们成像激光诱导荧光从一个超冷的中性等离子体映射等离子体的大小作为一个函数的时间范围内的磁场强度。垂直于磁场方向的渐近膨胀速度随着磁场强度的增大而迅速下降。我们观察到，在平行和垂直方向上，初始高斯空间分布在整个扩展过程中都保持高斯分布。我们将这些观测结果与扩散模型和自相似膨胀模型进行比较，结果表明，这两种模型都不能再现在本研究中使用的整个磁场范围内观察到的行为。对磁化超冷等离子体的膨胀进行建模提出了一个重要的理论挑战。
In strongly magnetized neutral plasmas, electron motion is reduced perpendicular to the magnetic field direction. This changes dynamical plasma properties such as temperature equilibration, spatial density evolution, electron pressure, and thermal and electrical conductivity. In this paper we report measurements of free plasma expansion in the presence of a strong magnetic field. We image laser-induced fluorescence from an ultracold neutralplasma to map the plasma size as a function of time for a range of magnetic field strengths. The asymptotic expansion velocity perpendicular to the magnetic field direction falls rapidly with increasing magnetic field strength. We observe that the initially Gaussian spatial distribution remains Gaussian throughout the expansion in both the parallel and perpendicular directions. We compare these observations with a diffusion model and with a self-similar expansion model and show that neither of these models reproduces the observed behavior over the entire range of magnetic fields used in this study. Modeling the expansion of a magnetized ultracold plasma poses a nontrivial theoretical challenge.