Snapshots of laser wakefields


Tabletop plasma accelerators can now produce GeV-range electron beams1,2,3,4,5 and femtosecond X-ray pulses6, providing compact radiation sources for medicine, nuclear engineering, materials science and high-energy physics7. In these accelerators, electrons surf on electric fields exceeding 100 GeV m−1, which is more than 1,000 times stronger than achievable in conventional accelerators. These fields are generated within plasma structures (such as Langmuir waves8 or electron density ‘bubbles’9) propagating near light speed behind laser2,3,4 or charged-particle5 driving pulses. Here, we demonstrate single-shot visualization of laser-wakefield accelerator structures for the first time. Our ‘snapshots’ capture the evolution of multiple wake periods, detect structure variations as laser–plasma parameters change, and resolve wavefront curvature; features never previously observed.

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Figure 1: Experimental setup for FDH of laser wakefields.
Figure 2: Small-amplitude wakes with flat wavefronts.
Figure 3: Strongly driven wake with curved wavefronts.
Figure 4: Axial lineouts of ionization front and wake oscillations.


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This work was supported by US Department of Energy grant DE-FG03-96ER40954 and US National Science Foundation Physics Frontier Center grant PHY-0114336.

Author information

N.H.M. designed and set up the experiment and data acquisition system and acquired and analysed all data presented, with assistance from S.R. A.M. supervised the experiments on site. V.Y. supervised construction and operation of the HERCULES laser system, and V.C. and G.K. operated it during the experiments. P.R. assisted with characterization of laser pulses and computerized data acquisition. T.M. provided a key insight in configuring the chirped probe pulses. S.K. and G.S. carried out all WAKE simulations presented in the paper, and S.S.B. confirmed them independently with a separate code and contributed to theoretical interpretation. M.C.D. conceived and co-supervised the experiment, and wrote the paper. All authors discussed the results and commented on the manuscript.

Correspondence to N. H. Matlis or M. C. Downer.

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Supplementary information

Supplementary Information, Fig. S1 (PDF 7396 kb)

Supplementary Information, Fig. S1 (PDF 53 kb)

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