Gas-filled capillary discharge waveguides are commonly used as media for plasma wakefield accelerators. We show that effective waveguides can be manufactured using a femtosecond laser micromachining technique to produce a linearly tapered plasma density, which enables the energy of the accelerator to be enhanced significantly. A laser guiding efficiency in excess of 82% at sub-relativistic intensities has been demonstrated in a 40 mm long capillary with a diameter tapering from 320 μm to 270 μm, which gives rise to an on-axis, time-averaged plasma density that varies from 1.0 × 1018 cm−3 to 1.6 × 1018 cm−3.
- tapered discharge
- capillary waveguides
- laser plasma
- wakefield accelerator
Abu-Azoum, S. S., Wiggins, M., Ersfeld, B., Hart, K., Vieux, G., Yang, X., Welsh, G. H., Issac, R. C., Reijnders, M. P., Jones, D. R., & Jaroszynski, D. A. (2012). Linearly tapered discharge capillary waveguides as a medium for a laser plasma wakefield accelerator. Applied Physics Letters, 100. https://doi.org/10.1063/1.3674309