Anomalous beam transport through gabor (plasma) lens prototype

Nonnenmacher, Toby and Dascalu, Titus-Stefan and Bingham, Robert and Cheung, Chung Lim and Lau, Hin-Tung and Long, Ken and Pozimski, Jürgen and Whyte, Colin (2021) Anomalous beam transport through gabor (plasma) lens prototype. Applied Sciences, 11 (10). 4357. ISSN 2076-3417 (https://doi.org/10.3390/app11104357)

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Abstract

An electron plasma lens is a cost-effective, compact, strong-focusing element that can ensure efficient capture of low-energy proton and ion beams from laser-driven sources. A Gabor lens prototype was built for high electron density operation at Imperial College London. The parameters of the stable operation regime of the lens and its performance during a beam test with 1.4 MeV protons are reported here. Narrow pencil beams were imaged on a scintillator screen 67 cm downstream of the lens. The lens converted the pencil beams into rings that show position-dependent shape and intensity modulation that are dependent on the settings of the lens. Characterisation of the focusing effect suggests that the plasma column exhibited an off-axis rotation similar to the m=1 diocotron instability. The association of the instability with the cause of the rings was investigated using particle tracking simulations.