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Spatially confined propagation of intense ultraviolet radiation in plasmas.

机译：等离子体中强紫外线辐射的空间限制传播。

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摘要

X-ray amplification requires a high energy deposition rate in a high aspect-ratio volume. High power lasers for x-ray laser pumping have become available with the development of the short pulse and high intensity laser technology capable of producing pulses with a peak power as high as 10{dollar}sp{lcub}12{rcub}{dollar} watts. Short pulses of high intensity x-ray have been observed in laser-plasma interactions, which encurages many scientists actively pursuing the goal of constructing practical x-ray lasers. Our approach has concentrated on producing high aspect ratio x-ray amplifying medium by spatially confined propagation of high power laser pulse in plasmas.; A high intensity laser beam induces nonlinear refractive index changes in plasma. In the case of subpicosecond ultrahigh power laser-plasma interaction, the dominant mechanisms responsible for the refractive index change in plasmas are: (1) the relativistic free electron mass increase due to the increase of electron oscillation velocity in the intense electromagnetic field of the laser pulses; and (2) displacement of free electrons out of the high intensity region of the laser beam by ponderomotive force. Both of the above effects lead to a refractive index change of the plasma, which in turn has a positive lensing effect on the beam. If the focusing effect is strong enough to overcome diffraction the beam will stay in a spatially confined mode of propagation. This confined propagation provides an effective method of concentrating energy. The field intensity associated with the confined propagation is so high that the highly excited medium with high aspect ratio suitable for x-ray amplification can be achieved.; In this research we have successfully demonstrated spatially confined propagation of 500 GW subpicosecond laser pulse in laser induced plasma. The measured diameter of the propagation is less than 2 {dollar}mu{dollar}m and the aspect ratio of the confined propagation is over 1000. The filed intensity associated with the propagation is estimated to the order of 10{dollar}sp{lcub}19{rcub}{dollar} W/cm{dollar}sp2{dollar}. Qualitatively good agreements are reached by comparing the experimental results with theoretical calculations involving the relativistic and ponderomotive nonlinearity of the medium.
机译：X射线放大需要高纵横比体积中的高能量沉积速率。随着短脉冲和高强度激光技术的发展，用于X射线激光泵浦的高功率激光器已经问世，该技术能够产生峰值功率高达10 {dollar} sp {lcub} 12 {rcub} {dollar}的脉冲瓦特。在激光-等离子体相互作用中观察到高强度X射线的短脉冲，这促使许多科学家积极地追求构建实用的X射线激光器的目标。我们的方法集中在通过高功率激光脉冲在等离子体中的空间受限传播来产生高纵横比的X射线放大介质。高强度激光束引起等离子体中的非线性折射率变化。在亚皮秒级超高功率激光-等离子体相互作用的情况下，造成等离子体折射率变化的主要机理是：（1）由于激光的强电磁场中电子振荡速度的增加，相对论自由电子质量增加。脉冲（2）自由电子通过质动力将其移出激光束的高强度区域。以上两种作用都会导致等离子体的折射率发生变化，从而对光束产生正透镜效应。如果聚焦效果足以克服衍射，则光束将停留在空间受限的传播模式下。这种有限的传播提供了一种有效的能量聚集方法。与受限传播相关的场强是如此之高，以致于可以获得具有高纵横比的高激发介质，适合于X射线放大。在这项研究中，我们成功地证明了500 GW亚皮秒激光脉冲在激光诱导等离子体中的空间限制传播。测得的传播直径小于2 {μm}美元，局限传播的长宽比超过1000。与传播相关的场强估计约为10 {sp} lcub } 19 {rcub} {dollar} W / cm {dollar} sp2 {dollar}。通过将实验结果与涉及介质的相对论和质子动力非线性的理论计算进行比较，可以得出定性良好的协议。

著录项

  • 作者

    Shi, Xiaomei.;

  • 作者单位

    University of Illinois at Chicago.;

  • 授予单位 University of Illinois at Chicago.;
  • 学科 Physics Radiation.; Physics Optics.
  • 学位 Ph.D.
  • 年度 1992
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 原子核物理学、高能物理学;光学;
  • 关键词

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