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Title: Experimental evidence of beam-foil plasma creation during ion-solid interaction

Abstract

Charge state evolution of the energetic projectile ions during the passage through thin carbon foils has been revisited using the X-ray spectroscopy technique. Contributions from the bulk and the solid surface in the charge changing processes have been segregated by measuring the charge state distribution of the projectile ions in the bulk of the target during the ion–solid interaction. Interestingly, the charge state distribution measured in the bulk exhibits Lorentzian profile in contrast to the well-known Gaussian structure observed using the electromagnetic methods and the theoretical predictions. The occurrence of such behavior is a direct consequence of the imbalance between charge changing processes, which has been seen in various cases of the laboratory plasma. It suggests that the ion-solid collisions constitute high-density, localized plasma in the bulk of the solid target, called the beam-foil plasma. This condensed beam-foil plasma is similar to the high-density solar and stellar plasma which may have practical implementations in various fields, in particular, plasma physics and nuclear astrophysics. The present work suggests further modification in the theoretical charge state distribution calculations by incorporating the plasma coupling effects during the ion–solid interactions. Moreover, the multi-electron capture from the target exit surface has been confirmed through comparisonmore » between experimentally measured and theoretically predicted values of the mean charge state of the projectile ions.« less

Authors:
;  [1]
  1. Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)
Publication Date:
OSTI Identifier:
22599982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; 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:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASTROPHYSICS; BEAMS; CARBON; CHARGE STATES; DENSITY; ELECTRON CAPTURE; ELECTRONS; FOILS; FORECASTING; GAUSSIAN PROCESSES; INTERACTIONS; IONS; PLASMA; PROJECTILES; SOLIDS; SURFACES; X RADIATION; X-RAY SPECTROSCOPY

Citation Formats

Sharma, Prashant, E-mail: prashant@iuac.res.in, and Nandi, Tapan. Experimental evidence of beam-foil plasma creation during ion-solid interaction. United States: N. p., 2016. Web. doi:10.1063/1.4960042.
Sharma, Prashant, E-mail: prashant@iuac.res.in, & Nandi, Tapan. Experimental evidence of beam-foil plasma creation during ion-solid interaction. United States. doi:10.1063/1.4960042.
Sharma, Prashant, E-mail: prashant@iuac.res.in, and Nandi, Tapan. 2016. "Experimental evidence of beam-foil plasma creation during ion-solid interaction". United States. doi:10.1063/1.4960042.
@article{osti_22599982,
title = {Experimental evidence of beam-foil plasma creation during ion-solid interaction},
author = {Sharma, Prashant, E-mail: prashant@iuac.res.in and Nandi, Tapan},
abstractNote = {Charge state evolution of the energetic projectile ions during the passage through thin carbon foils has been revisited using the X-ray spectroscopy technique. Contributions from the bulk and the solid surface in the charge changing processes have been segregated by measuring the charge state distribution of the projectile ions in the bulk of the target during the ion–solid interaction. Interestingly, the charge state distribution measured in the bulk exhibits Lorentzian profile in contrast to the well-known Gaussian structure observed using the electromagnetic methods and the theoretical predictions. The occurrence of such behavior is a direct consequence of the imbalance between charge changing processes, which has been seen in various cases of the laboratory plasma. It suggests that the ion-solid collisions constitute high-density, localized plasma in the bulk of the solid target, called the beam-foil plasma. This condensed beam-foil plasma is similar to the high-density solar and stellar plasma which may have practical implementations in various fields, in particular, plasma physics and nuclear astrophysics. The present work suggests further modification in the theoretical charge state distribution calculations by incorporating the plasma coupling effects during the ion–solid interactions. Moreover, the multi-electron capture from the target exit surface has been confirmed through comparison between experimentally measured and theoretically predicted values of the mean charge state of the projectile ions.},
doi = {10.1063/1.4960042},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = 2016,
month = 8
}
  • Experimental evidence is presented that an unmodulated electron beam moving through a homogeneous plasma is unstable. A 40-mm long Ar discharge is observed by probe methods, and the densities and oscillatory properties of the plasma electrons are found. It is suggested that the beam of electrons (which comes from the cathode) becomes unstable, and excites growing longitudinal plasma oscillations, as a result of a decreasing plasma density gradient. (T.F.H.)
  • The origin of beam-foil convoy electrons has been a subject of many controversial interpretations and discussions. In this work, velocity distributions of electrons ejected into the forward direction from a carbon-foil target have been measured with incident proton beams of energies between 60 and 300 keV, and under the same experimental conditions as equivalent measurements recently performed in this laboratory with a He-gas target. Cusp widths are discussed as a function of projectile velocity and instrumental angular acceptance by taking fractional peak heights from the base line as well as by previously subtracting a background obtained by joining peak tails.more » It is concluded that neither of these procedures is valid. On the other hand, measured electron spectra can be well fitted in terms of a general parametric expression of the scattering amplitude for an electron transfer to the continuum process. The absence of a strong negative cusp skewness, as was observed with the gas target, hints in the direction of an electron loss rather than an electron capture to the continuum process. A significant background contribution that is absent for a single-collision electron transfer to the continuum process is interpreted as due to the emission of secondary electrons that are not correlated to the emerging projectiles.« less
  • The dynamic behavior of the plasma produced from a thin foil target irradiated by a focused intense electron beam is observed optically by the shadowgraphy and interferometry. Evidence of anomalous stopping of intense electron beam on the surface of the low-Z target is shown experimentally.
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