Monoenergetic beams of relativistic electrons from intense laser-plasma interactions
Monoenergetic beams of relativistic electrons from intense laser-plasma interactions
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DOI：
10.1038/nature02939
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发表时间：
2004-09-30
期刊：
影响因子：
64.8
通讯作者：
Krushelnick, K
中科院分区：
文献类型：
--
作者：
Mangles, SPD;Murphy, CD;Krushelnick, K
现在，适合大学规模实验室的高功率激光器在高重复率下的聚焦强度可以达到10（19）瓦厘米（-2）以上。这种激光器能够产生高能电子束（2-11）、质子束（12）和伽马射线束（13）。相对论性电子是通过激光脉冲在等离子体中传播时产生的大振幅相对论性等离子体波的破缺（9,10,14）或通过激光场与等离子体中的电子之间的直接相互作用（15）产生的。然而，先前的激光等离子体实验产生的电子束有很大的能量扩散（6,7,9,14），限制了它们的潜在应用。在这里，我们报告了由强烈的激光-等离子体相互作用产生的电子束的高分辨率能量测量，表明-在特定的等离子体条件下-有可能产生低发散和小能量扩散（小于3%）的相对论性电子束。在等离子体密度的电子能谱中观察到单能特征，其密度刚好高于等离子体波破裂所需的阈值。这些特征在电子能谱中被一致地观察到，尽管观察到光束的能量在每个镜头之间变化。如果能解决能量可重复性的问题，就有可能产生可调谐能量的超短单能电子束，这对“桌面”粒子加速器的未来发展有很大的希望。
High-power lasers that fit into a university-scale laboratory(1) can now reach focused intensities of more than 10(19) W cm(-2) at high repetition rates. Such lasers are capable of producing beams of energetic electrons(2-11), protons(12) and gamma-rays(13). Relativistic electrons are generated through the breaking(9,10,14) of large-amplitude relativistic plasma waves created in the wake of the laser pulse as it propagates through a plasma, or through a direct interaction between the laser field and the electrons in the plasma(15). However, the electron beams produced from previous laser - plasma experiments have a large energy spread(6,7,9,14), limiting their use for potential applications. Here we report high-resolution energy measurements of the electron beams produced from intense laser - plasma interactions, showing that - under particular plasma conditions - it is possible to generate beams of relativistic electrons with low divergence and a small energy spread ( less than three per cent). The monoenergetic features were observed in the electron energy spectrum for plasma densities just above a threshold required for breaking of the plasma wave. These features were observed consistently in the electron spectrum, although the energy of the beam was observed to vary from shot to shot. If the issue of energy reproducibility can be addressed, it should be possible to generate ultrashort monoenergetic electron bunches of tunable energy, holding great promise for the future development of 'table-top' particle accelerators.