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Mass spectrometer calibration of Cosmic Dust Analyzer

Ahrens, Thomas J. and Gupta, Satish C. and Jyoti, G. and Beauchamp, J. L. (2003) Mass spectrometer calibration of Cosmic Dust Analyzer. Journal of Geophysical Research E, 108 (E2). Art. No. 5007. ISSN 0148-0227. doi:10.1029/2002JE001912.

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The time-of-flight (TOF) mass spectrometer (MS) of the Cosmic Dust Analyzer (CDA) instrument aboard the Cassini spacecraft is expected to be placed in orbit about Saturn to sample submicrometer-diameter ring particles and impact ejecta from Saturn's satellites. The CDA measures a mass spectrum of each particle that impacts the chemical analyzer sector of the instrument. Particles impact a Rh target plate at velocities of 1-100 km/s and produce some 10^(−8) to 10^(−5) times the particle mass of positive valence, single-charged ions. These are analyzed via a TOF MS. Initial tests employed a pulsed N2 laser acting on samples of kamacite, pyrrhotite, serpentine, olivine, and Murchison meteorite induced bursts of ions which were detected with a microchannel plate and a charge sensitive amplifier (CSA). Pulses from the N_2 laser (10^(11) W/cm^2) are assumed to simulate particle impact. Using aluminum alloy as a test sample, each pulse produces a charge of ∼4.6 pC (mostly Al^(+1)), whereas irradiation of a stainless steel target produces a ∼2.8 pC (Fe^(+1)) charge. Thus the present system yields ∼10^(−5)% of the laser energy in resulting ions. A CSA signal indicates that at the position of the microchannel plate, the ion detector geometry is such that some 5% of the laser-induced ions are collected in the CDA geometry. Employing a multichannel plate detector in this MS yields for Al-Mg-Cu alloy and kamacite targets well-defined peaks at 24 (Mg^(+1)), 27(Al^(+1)), and 64 (Cu^(+1)) and 56 (Fe^(+1)), 58 (Ni^(+1)), and 60 (Ni^(+1)) dalton, respectively.

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URLURL TypeDescription DOIArticle Information
Beauchamp, J. L.0000-0001-8839-4822
Additional Information:© 2003 by the American Geophysical Union. Received 11 April 2002; revised 24 July 2002; accepted 28 August 2002; published 14 February 2003. Research supported by NASA and DOE. We thank V. Nenow for developing the sample-rotating fixture. We appreciate the helpful comments of two reviewers. Thanks are due to R. Srama, E. Grün, J. Bradley, and S. K. Sikka for their interest and encouragement. Contribution 8872, Division of Geological and Planetary Sciences (Caltech).
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Department of Energy (DOE)UNSPECIFIED
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Caltech Division of Geological and Planetary Sciences8872
Issue or Number:E2
Record Number:CaltechAUTHORS:20141022-101106717
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Official Citation:Jyoti, G., S. C. Gupta, T. J. Ahrens, and J. L. Beauchamp, Mass spectrometer calibration of Cosmic Dust Analyzer, J. Geophys. Res., 108(E2), 5007, doi:10.1029/2002JE001912, 2003
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50675
Deposited By: Tony Diaz
Deposited On:22 Oct 2014 19:12
Last Modified:10 Nov 2021 18:59

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