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arXiv · 0712.2732

Longitudinal Ion Acceleration from High-Intensity Laser Interactions with Underdense Plasma

L. Willingale·S. P. D. Mangles·P. M Nilson·R. J. Clarke·A. E. Dangor·M. C. Kaluza·S. Karsch·K. L. Lancaster·W. B. Mori·J. Schreiber·A. G. R. Thomas·M. S. Wei·K. Krushelnick·Z. Najmudin
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Abstract

Longitudinal ion acceleration from high-intensity (I ~ 10^20 Wcm^-2) laser interactions with helium gas jet targets (n_e ~ 0.04 n_c) have been observed. The ion beam has a maximum energy for He^2+ of approximately 40 MeV and was directional along the laser propagation path, with the highest energy ions being collimated to a cone of less than 10 degrees. 2D particle-in-cell simulations have been used to investigate the acceleration mechanism. The time varying magnetic field associated with the fast electron current provides a contribution to the accelerating electric field as well as providing a collimating field for the ions. A strong correlation between the plasma density and the ion acceleration was found. A short plasma scale-length at the vacuum interface was observed to be beneficial for the maximum ion energies, but the collimation appears to be improved with longer scale-lengths due to enhanced magnetic fields in the ramp acceleration region.

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L. Willingale, S. P. D. Mangles, P. M Nilson, R. J. Clarke, A. E. Dangor, M. C. Kaluza, S. Karsch, K. L. Lancaster, W. B. Mori, J. Schreiber, A. G. R. Thomas, M. S. Wei, K. Krushelnick, Z. Najmudin. 2007-12-17. Longitudinal Ion Acceleration from High-Intensity Laser Interactions with Underdense Plasma. https://doi.org/10.1109/tps.2008.927357

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