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Title: Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Fe g+ Ions Impacting H 2O

Abstract

Charge exchange (CE) plays a fundamental role in the collisions of solar- and stellar-wind ions with lunar and planetary exospheres, comets, and circumstellar clouds. Reported herein are absolute cross sections for single, double, triple, and quadruple CE of Fe q+ (q = 5-13) ions with H 2O at a collision energy of 7q keV. One measured value of the pentuple CE is also given for Fe 9+ ions. An electron cyclotron resonance ion source is used to provide currents of the highly charged Fe ions. Absolute data are derived from knowledge of the target gas pressure, target path length, and incident and charge-exchanged ion currents. Experimental cross sections are compared with new results of the n-electron classical trajectory Monte Carlo approximation. The radiative and non-radiative cascades following electron transfers are approximated using scaled hydrogenic transition probabilities and scaled Auger rates. Also given are estimates of cross sections for single capture, and multiple capture followed by autoionization, as derived from the extended overbarrier model. These estimates are based on new theoretical calculations of the vertical ionization potentials of H 2O up to H 2O 10+.

Authors:
 [1];  [2];  [3];  [4];  [5];  [5];  [6];  [1]
  1. Jet Propulsion Laboratory/Caltech
  2. ORNL
  3. Pomona College
  4. Queen's University, Belfast
  5. California Institute of Technology, Pasadena
  6. Indiana Wesleyan University, Marion
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Work for Others (WFO)
OSTI Identifier:
993798
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 722; Journal Issue: 1; Journal ID: ISSN 0004--637X
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; AUTOIONIZATION; CHARGE EXCHANGE; CLOUDS; COMETS; CROSS SECTIONS; DATA; ELECTRON CYCLOTRON-RESONANCE; ELECTRON TRANSFER; ION SOURCES; IONIZATION POTENTIAL; TARGETS

Citation Formats

Simcic, J, Schultz, David Robert, Mawhorter, R J, Greenwood, J B, Winstead, C, McKoy, B V, Smith, S J, and Chutjian, A. Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Feg+ Ions Impacting H2O. United States: N. p., 2010. Web. doi:10.1088/0004-637X/722/1/435.
Simcic, J, Schultz, David Robert, Mawhorter, R J, Greenwood, J B, Winstead, C, McKoy, B V, Smith, S J, & Chutjian, A. Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Feg+ Ions Impacting H2O. United States. doi:10.1088/0004-637X/722/1/435.
Simcic, J, Schultz, David Robert, Mawhorter, R J, Greenwood, J B, Winstead, C, McKoy, B V, Smith, S J, and Chutjian, A. Wed . "Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Feg+ Ions Impacting H2O". United States. doi:10.1088/0004-637X/722/1/435.
@article{osti_993798,
title = {Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Feg+ Ions Impacting H2O},
author = {Simcic, J and Schultz, David Robert and Mawhorter, R J and Greenwood, J B and Winstead, C and McKoy, B V and Smith, S J and Chutjian, A},
abstractNote = {Charge exchange (CE) plays a fundamental role in the collisions of solar- and stellar-wind ions with lunar and planetary exospheres, comets, and circumstellar clouds. Reported herein are absolute cross sections for single, double, triple, and quadruple CE of Feq+ (q = 5-13) ions with H2O at a collision energy of 7q keV. One measured value of the pentuple CE is also given for Fe9+ ions. An electron cyclotron resonance ion source is used to provide currents of the highly charged Fe ions. Absolute data are derived from knowledge of the target gas pressure, target path length, and incident and charge-exchanged ion currents. Experimental cross sections are compared with new results of the n-electron classical trajectory Monte Carlo approximation. The radiative and non-radiative cascades following electron transfers are approximated using scaled hydrogenic transition probabilities and scaled Auger rates. Also given are estimates of cross sections for single capture, and multiple capture followed by autoionization, as derived from the extended overbarrier model. These estimates are based on new theoretical calculations of the vertical ionization potentials of H2O up to H2O10+.},
doi = {10.1088/0004-637X/722/1/435},
journal = {Astrophysical Journal},
issn = {0004--637X},
number = 1,
volume = 722,
place = {United States},
year = {2010},
month = {9}
}