The helium atom in intense UV and XUV laser fields: rescattering-induced double ionization and ionization scaling laws

强紫外和极紫外激光场中的氦原子：重散射引起的双电离和电离标度定律

• 批准号: EP/E016588/1
• 负责人: K Taylor
• 金额: $ 44.68万
• 依托单位: Queen's University Belfast
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE016588%2F1
• 关键词: helium; atom; intense; UV; XUV

At sufficiently high laser intensities, multi-electron atoms undergonon-sequential double ionization (NSDI), a process in which electronsare ejected near-simulteously in highly correlated (entangled) pairs.Helium, the simplest of all multi-electron atoms, presentstheorists with a unique opportunity to study these highly correlatedintense-field processes with an unprecedented accuracy. Despite therelatively simple structure of helium, the helium-laser Schroedingerequation, governing the dynamics of the system, admits few if anyapproximations in the limit of high intensity laser radiation. In theintense fields used to create NSDI, all terms of the helium-laserSchroedinger equation and all degrees of freedom are exercisedsimultaneously. The only reliable treatment of this problem has provedto be via high-accuracy numerical solution of the full Schroedinger equation.Over the last decade we have developed the computational methods, and thecomputer codes necessary to solve this problem on parallel computers.Our code is capable of solving the full (time-dependent and full-dimensional)helium-laser Schroedinger equation over a wide range of laserfrequencies and intensities. We have no rivals in this capability world-wide.Our code is still alone in its ability to generate accurate reliable solutionsat frequencies that range from the optical to the XUV, and atlaser intensities as high as can be achieved in practical experiments.Our intention is to calculate the detailed ionization dynamics of laser-drivenhelium in the UV to XUV range of laser wavelengths (roughly 100 nm to 7nm).In the intense field limit, this is very much uncharted territory,because until very recently it was impossible to build intense-fieldlasers at these wavelengths. Six months ago this changed with thecompletion of the first phase of DESY Free Electron Laser (FEL) nearHamburg. Another more ambitious FEL is under construction at Stanford.As just one illustration of the high importance of atom-laser physicsin this limit, we note a recent successful practical application of thenon-sequential double ionization (NSDI) mentioned above, in which trainsof light pulses of duration 100 attoseconds (the shortest everobserved) were created as a direct result of NSDI and used toperform time-resolved measurements of the same order. The laserused to drive the NSDI was 800nm. The prospect of producing evenshorter pulses by using intense UV lasers is a particularly exciting potentialapplication of laser-driven helium in the UV.

在足够高的激光强度下，多电子原子进行非顺序双电离（NSDI），这是一种电子几乎同时以高度相关（纠缠）对喷射的过程。氦是所有多电子原子中最简单的，它为理论学家提供了一个独特的机会，以前所未有的精度研究这些高度相关的强场过程。尽管氦的结构相对简单，但控制系统动力学的氦-激光薛定谔方程在高强度激光辐射的极限下几乎不允许任何近似。在用于产生NSDI的强磁场中，氦-激光薛定谔方程的所有项和所有自由度都是同时进行的。这个问题的唯一可靠的处理方法已被证明是通过高精度的完整薛定谔方程的数值解。在过去的十年里，我们已经开发出了在并行计算机上解决这个问题所需的计算方法和计算机代码。我们的代码能够在广泛的激光频率和强度范围内求解全（时间相关和全维）氦激光薛定谔方程。在这方面，我们在世界范围内没有对手。我们的代码仍然能够生成准确可靠的解决方案，从光学到XUV的频率范围，以及在实际实验中可以实现的高激光强度。我们的目的是计算激光驱动氦在激光波长（大约100 nm到7nm）的UV到XUV范围内的详细电离动力学。在强场极限下，这是一个未知的领域，因为直到最近，人们还不可能制造出这种波长的强场激光器。六个月前，随着德国汉堡附近DESY自由电子激光器（FEL）第一阶段的完成，这种情况发生了变化。另一个更加雄心勃勃的自由电子实验室正在斯坦福大学建设中。作为原子激光物理在这一极限中高度重要性的一个例证，我们注意到最近成功的非连续双电离（NSDI）的实际应用，其中持续时间为100阿秒（有史以来最短的）的光脉冲序列被创建为NSDI的直接结果，并用于执行相同顺序的时间分辨率测量。驱动NSDI的激光波长为800nm。利用强紫外激光产生更短脉冲的前景是激光驱动氦在紫外中的一个特别令人兴奋的潜在应用。

项目成果

Direct versus delayed pathways in strong-field non-sequential double ionization

• DOI: 10.1088/1367-2630/13/4/043001
• 发表时间: 2011-04-04
• 期刊: NEW JOURNAL OF PHYSICS
• 影响因子: 3.3
• 作者: Emmanouilidou, A.;Parker, J. S.;Taylor, K. T.
• 通讯作者: Taylor, K. T.