High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

Alejo, A. and Kar, S. and Tebartz, A. and Ahmed, H. and Astbury, S. and Carroll, D.C. and Ding, J. and Doria, D. and Higginson, A. and McKenna, P. and Neumann, N. and Scott, G.G. and Wagner, F. and Roth, M. and Borghesi, M. (2016) High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams. Review of Scientific Instruments, 87 (8). ISSN 0034-6748

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    Abstract

    We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally-shaped electric plates, proposed by Gwynne et al. in Rev. Sci. Instrum. 85, 033304 (2014). While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.