A capillary gas cell for laser wakefield acceleration was developed with the aid of three-dimensional computational fluid dynamics simulations. The gas cell was specially designed to provide upward density tapering in the longitudinal direction, which is expected to suppress the dephasing problem in laser wakefield acceleration by keeping the accelerated electrons in the acceleration phase of the wake wave. The density-tapered capillary gas cell was fabricated by sapphire plates, and its performance characteristics were tested. The capillary gas cell was filled with a few hundred millibars of hydrogen gas, and a Ti:sapphire laser pulse with a peak power of 3.8 TW and a pulse duration of 40 fs (full width at half maximum) was sent through the capillary hole, which has a length of 7 mm and a square cross section of 350 × 350 µm². The laser-produced hydrogen plasma in the capillary hole was then diagnosed two-dimensionally by using a transverse Mach–Zehnder interferometer. The capillary gas cell was found to provide an upward plasma density tapering in the range of 10¹⁸ cm⁻³–10¹⁹ cm⁻³, which has a potential to enhance the electron beam energy in laser wakefield acceleration experiments.

中文翻译：

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密度锥化毛细管气体池的开发，用于激光尾波加速

借助三维计算流体动力学模拟，开发了用于激光尾波加速的毛细管气室。气室经过专门设计，可以在纵向上提供向上的锥度，这有望通过将加速后的电子保持在尾波的加速阶段来抑制激光尾场加速中的相移问题。用蓝宝石板制造密度渐缩的毛细管气室，并对其性能进行了测试。毛细管气体池中充满了数百毫巴的氢气，并通过毛细管孔发送了峰值功率为3.8 TW，脉冲持续时间为40 fs（半峰全宽）的Ti：蓝宝石激光脉冲，长度为7毫米，横截面为350×350μ中号²。然后使用横向马赫-曾德尔干涉仪对毛细管孔中激光产生的氢等离子体进行二维诊断。发现毛细管气室在10 ¹⁸ cm ^-3 –10 ¹⁹ cm ^-3的范围内提供向上的等离子体密度逐渐减小，这在激光尾场加速实验中具有增强电子束能量的潜力。