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

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. [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.

Authors:
; ; ; ;  [1]; ; ;  [2]; ; ;  [3]; ;  [4];  [5];  [6]
  1. Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom)
  2. Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstrasse 9, D-64289 Darmstadt (Germany)
  3. Central Laser Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom)
  4. Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)
  5. GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany)
  6. Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstraße 9, D-64289 Darmstadt (Germany)
Publication Date:
OSTI Identifier:
22597678
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CAPTURE; CONFIGURATION; DESIGN; ELECTRODES; ION BEAMS; IONS; LASERS; PARABOLAS; PLATES; RELATIVISTIC RANGE; RESOLUTION; SPECTRA; SPECTROMETERS

Citation Formats

Alejo, A., Kar, S., E-mail: s.kar@qub.ac.uk, Ahmed, H., Doria, D., Borghesi, M., Tebartz, A., Ding, J., Neumann, N., Astbury, S., Carroll, D. C., Scott, G. G., Higginson, A., McKenna, P., Wagner, F., and Roth, M. High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams. United States: N. p., 2016. Web. doi:10.1063/1.4961028.
Alejo, A., Kar, S., E-mail: s.kar@qub.ac.uk, Ahmed, H., Doria, D., Borghesi, M., Tebartz, A., Ding, J., Neumann, N., Astbury, S., Carroll, D. C., Scott, G. G., Higginson, A., McKenna, P., Wagner, F., & Roth, M. High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams. United States. doi:10.1063/1.4961028.
Alejo, A., Kar, S., E-mail: s.kar@qub.ac.uk, Ahmed, H., Doria, D., Borghesi, M., Tebartz, A., Ding, J., Neumann, N., Astbury, S., Carroll, D. C., Scott, G. G., Higginson, A., McKenna, P., Wagner, F., and Roth, M. 2016. "High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams". United States. doi:10.1063/1.4961028.
@article{osti_22597678,
title = {High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams},
author = {Alejo, A. and Kar, S., E-mail: s.kar@qub.ac.uk and Ahmed, H. and Doria, D. and Borghesi, M. and Tebartz, A. and Ding, J. and Neumann, N. and Astbury, S. and Carroll, D. C. and Scott, G. G. and Higginson, A. and McKenna, P. and Wagner, F. and Roth, M.},
abstractNote = {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. [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.},
doi = {10.1063/1.4961028},
journal = {Review of Scientific Instruments},
number = 8,
volume = 87,
place = {United States},
year = 2016,
month = 8
}
  • Thomson Parabola (TP) spectrometers are widely used devices for laser-driven beam diagnostics as they provide a complete set of information on the accelerated particles. A novel TP has been developed at LNS with a design able to detect protons up to 20 MeV. The layout design and some results obtained during the experimental campaign at PALS laboratory will be reported in the following.
  • Here, we report on the development of a novel high resolution and high dispersion Thomson parabola for simultaneously resolving protons and low-Z ions of more than 100 MeV/nucleon necessary to explore novel laser ion acceleration schemes. High electric and magnetic fields enable energy resolutions of {Delta}E/E < 5% at 100 MeV/nucleon and impede premature merging of different ion species at low energies on the detector plane. First results from laser driven ion acceleration experiments performed at the Trident Laser Facility demonstrate high resolution and superior species and charge state separation of this novel Thomson parabola for ion energies of moremore » than 30 MeV/nucleon.« less
  • A new, versatile Thomson parabola ion energy (TPIE) analyzer has been designed, constructed, and used at the OMEGA-EP facility. Laser-accelerated multi-MeV ions from hemispherical C targets are transmitted through a W pinhole into a multi-kG magnetic field and subsequently through a parallel electric field of up to 25 kV/cm. The ion drift region has a user-selected length of 10, 50, or 80 cm. With the highest fields, 400-MeV C{sup 6+} and C{sup 5+} may be resolved. TPIE is ten-inch manipulator (TIM)-mounted at OMEGA-EP and can be used opposite either of the EP ps beams. The instrument runs on pressure-interlocked 15-Vdcmore » power available in EP TIM carts. Flux control derives from the insertion depth into the target chamber and the user-selected pinhole dimensions. The detector consists of CR39 backed by an image plate. A fully relativistic simulation code for calculating ion trajectories was employed for design optimization. Excellent agreement of code predictions with the actual ion positions on the detectors is observed. Through pit counting of carbon-ion tracks in CR39, it is shown that conversion efficiency of laser light to energetic carbon ions exceeds {approx}5% for these targets.« less
  • A modification to the standard Thomson parabola spectrometer is discussed, which is designed to measure high energy (tens of MeV/nucleon), broad bandwidth spectra of multi-species ions accelerated by intense laser plasma interactions. It is proposed to implement a pair of extended, trapezoidal shaped electric plates, which will not only resolve ion traces at high energies, but will also retain the lower energy part of the spectrum. While a longer (along the axis of the undeflected ion beam direction) electric plate design provides effective charge state separation at the high energy end of the spectrum, the proposed new trapezoidal shape willmore » enable the low energy ions to reach the detector, which would have been clipped or blocked by simply extending the rectangular plates to enhance the electrostatic deflection.« less
  • A novel type of ion spectrometer for laser-produced plasma diagnostics is described. The Thomson parabola configuration is used to separate the expanding plasma ions according to their different charge-to-mass ratios. One particular ion species is subsequently collected by a parabola-shaped charge collector. In this way ion velocity distributions of a single charge-to-mass ratio are obtained through simple time-of-flight analysis. Measured ion energies can be as low as 1 keV per nucleon.