论文标题
激光加速，低差异15 MEV准单调电子束1 kHz
Laser-accelerated, low divergence 15 MeV quasi-monoenergetic electron bunches at 1 kHz
论文作者
论文摘要
我们证明了准单调电子电子的激光韦克菲尔德加速度以1 kHz的重复速率束高达15 meV，每束2.5 pc充电，并且核心的核心<7 mrad梁发散。加速度由5 FS驱动，<2.7 MJ激光脉冲，这是在薄薄的近乎密度氢气射流上的。低光束发散归因于对激光载体包络相位滑动的敏感性降低，使用激光极化和气流射流控制以两种方式实现：（1）电子在气流射流的等离子密度倾斜的唤醒中，以及（2）使用循环极化驱动脉冲。在往坡道中轻度波动的条件下，电子束轮廓具有与Kappa电子能量分布一致的2D Lorentzian形状。以前仅在空间或尘土飞扬的等离子体中观察到这种分布。我们将这种形状归因于密切相关的无碰撞束，并限制在二次Wakefield气泡电位上，其中横向速度空间扩散被气泡中的红移激光场赋予了束。
We demonstrate laser wakefield acceleration of quasi-monoenergetic electron bunches up to 15 MeV at 1 kHz repetition rate with 2.5 pC charge per bunch and a core with < 7 mrad beam divergence. Acceleration is driven by 5 fs, < 2.7 mJ laser pulses incident on a thin, near-critical density hydrogen gas jet. Low beam divergence is attributed to reduced sensitivity to laser carrier envelope phase slip, achieved in two ways using laser polarization and gas jet control: (1) electron injection into the wake on the gas jet's plasma density downramp, and (2) use of circularly polarized drive pulses. Under conditions of mild wavebreaking in the downramp, electron beam profiles have a 2D Lorentzian shape consistent with a kappa electron energy distribution. Such distributions had previously been observed only in space or dusty plasmas. We attribute this shape to the strongly correlated collisionless bunch confined by the quadratic wakefield bubble potential, where transverse velocity space diffusion is imparted to the bunch by the red-shifted laser field in the bubble.
