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arXiv 1402.5322physics.acc-phphysics.plasm-ph
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用两个不同波长的laser脉冲从laser尾场加速器产生低发射度电子束

Low emittance electron beam generation from a laser wakefield accelerator using two laser pulses with different wavelengths

X. L. Xu, Y. P. Wu, C. J. Zhang, F. Li, Y. Wan, J. F. Hua, C. -H. Pai, W. Lu, P. Yu, C. Joshi, W. B. Mori

摘要:

利用多维粒子模拟方法研究了在长波长激光驱动的非线性尾流场中,短波长激光脉冲触发的电离注入。我们发现,非常明亮的电子束可以产生通过这种双色方案在共线传播或横向碰撞几何。对于固定的激光强度$I$,具有较长/较短波长$λ$的激光具有较大/较小的有质动力势($\propto I λ^2$)。双色方案利用这一特性将注入过程与尾流场激发过程分离。通过使用较长波长的激光驱动器(例如,$10 \micro\meter$ CO $_2$激光器),由于其非常大的有质动力势,可以在相对低的激光强度下产生非常强的尾流。另一方面,短波长激光可以在尾流内部产生具有非常小的剩余动量($p_\perp\sim a_0\sim \sqrt{I}λ$)的电子,导致具有非常小的归一化发射度($\nano\meter$的数十)的电子束。使用粒子模拟,我们表明,一个$\sim10 \femto\second$电子束与$\sim4 \pico\coulomb$的电荷和$\sim 50 \nano\meter$的归一化发射率,可以通过结合一个10 $\micro\meter $驱动激光与400 $\nano\meter$注入激光,这是一个以上的数量级的改进时,获得的典型结果相比,一个单一的波长的激光用于尾迹形成和电离注入。

英文摘要:

Ionization injection triggered by short wavelength laser pulses inside a nonlinear wakefield driven by a longer wavelength laser is examined via multi-dimensional particle-in-cell simulations. We find that very bright electron beams can be generated through this two-color scheme in either collinear propagating or transverse colliding geometry. For a fixed laser intensity $I$, lasers with longer/shorter wavelength $λ$ have larger/smaller ponderomotive potential ($\propto I λ^2$). The two color scheme utilizes this property to separate the injection process from the wakefield excitation process. Very strong wakes can be generated at relatively low laser intensities by using a longer wavelength laser driver (e.g. a $10 \micro\meter$ CO$_2$ laser) due to its very large ponderomotive potential. On the other hand, short wavelength laser can produce electrons with very small residual momenta ($p_\perp\sim a_0\sim \sqrt{I}λ$) inside the wake, leading to electron beams with very small normalized emittances (tens of $\nano\meter$). Using particle-in-cell simulations we show that a $\sim10 \femto\second$ electron beam with $\sim4 \pico\coulomb$ of charge and a normalized emittance of $\sim 50 \nano\meter$ can be generated by combining a 10 $\micro\meter $ driving laser with a 400 $\nano\meter$ injection laser, which is an improvement of more than one order of magnitude compared to the typical results obtained when a single wavelength laser used for both the wake formation and ionization injection.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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