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Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Fe^(q+) Ions Impacting H_2O

Simcic, J. and Schultz, D. R. and Mawhorter, R. J. and Greenwood, J. B. and Winstead, C. and McKoy, B. V. and Smith, S. J. and Chutjian, A. (2010) Measurement and Calculation of Absolute Single and Multiple Charge Exchange Cross Sections for Fe^(q+) Ions Impacting H_2O. Astrophysical Journal, 722 (1). pp. 435-439. ISSN 0004-637X.

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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+).

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Additional Information:© 2010 The American Astronomical Society. Received 2010 July 2; accepted 2010 August 9; published 2010 September 21. The experimental work was carried out at JPL/Caltech, and was supported by the National Aeronautics and Space Administration through agreement with the California Institute of Technology. D.R.S. gratefully acknowledges support from the US Department of Energy under Contract No. DE-AC05-OR22464. Copyright 2010 California Institute of Technology.
Funding AgencyGrant Number
Department of EnergyDE-AC05-OR22464
Subject Keywords:comets: general; molecular processes; plasmas; solar wind
Issue or Number:1
Classification Code:PACS: 96.50.Ci; 96.30.Cw; 96.20.-n; 96.50.Vg; 96.15.Hy; 96.12.Jt
Record Number:CaltechAUTHORS:20101102-080809026
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Official Citation:J. Simcic et al 2010 ApJ 722 435 doi: 10.1088/0004-637X/722/1/435
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20629
Deposited By: Ruth Sustaita
Deposited On:02 Nov 2010 16:03
Last Modified:03 Oct 2019 02:13

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