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Fundamental Technologies
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Selected Publications
Paranicas, C., R. B. Decker, B. H. Mauk, S. M. Krimigis, T. P. Armstrong, and S. Jurac, Energetic Ion Composition in Saturn’s Magnetosphere Revisited, Geophys. Res. Lett., 31, L04810, doi: 10.1029/2003GL018899, 2004. Journal abstract, with link to full article.
| Abstract (draft).We present a new analysis of the composition of energetic charged particles in Saturn's inner magnetosphere. This analysis is motivated by a discovery made after the Voyager 1 and 2 Saturn encounters of penetrating electrons in some total ion measurement channels of the Low Energy Charged Particle detectors. From this new analysis, we predict that there is no significant increase in the ratio of heavy energetic ions to protons inward of the orbit of the satellite Dione, as previously thought. This implies that energetic ion sputtering of the icy rings and satellites produces much less water vapor than has been assumed based on past composition estimates. For protons between about 500 keV and a few MeV, we observe a decrease in measured flux inward of about L = 6 and suggest the cause of this decrease is not well understood. |
Paranicas, C., B. H. Mauk, R. E. McEntire, and T. P. Armstrong, The Radiation Environment near Io, Geophys. Res. Lett., 30 (18), 1919, doi:10.1029/2003GL017682, 2003. Journal abstract, with link to full article.
| Abstract (draft).Voyager and Galileo data taken near Io are used to calculate ion and electron energy spectra to study the interaction of Io with its space environment. Ion spectra for energetic protons, helium, oxygen and sulfur are presented for the first time. We find intensities of ions above 100 keV are more than an order of magnitude smaller than their counterparts at Europa. Oxygen ions appear to have net losses as they diffuse inward from Europa far exceeding losses of protons or sulfur ions. Estimates of surface sputtering rates by these particles suggest only a small fraction of the neutral gas supplied by Io comes from this process. Radiation dose rates into the surface are heavily dominated by electrons in less than ~1% of the surface area. |
Krupp, N., J. Woch, A. Lagg, S. A. Espinosa, S. Livi, S. M. Krimigis, D. G. Mitchell, D. J. Williams, A. F. Cheng, B. H. Mauk, R. W. McEntire, T. P. Armstrong, D. C. Hamilton, G. Gloeckler, J. Dandouras, and L. J. Lanzerotti, Leakage of Energetic Particles from Jupiter’s Dusk Magnetosphere: Dual Spacecraft Observations, Geophys. Res. Lett., 29 (15), doi: 10.1029/2001GL014290, 2002. Journal abstract, with link to full article.
| Abstract (draft).For the first time, two spacecraft, Galileo and Cassini, observed Jupiter's magnetosphere simultaneously for nearly half a year between October 2000 and March 2001. This provided an unprecedented opportunity to disentangle spatial and temporal aspects of the dynamics of the Jovian magnetosphere. In this paper we report new results on the source of the leakage of energetic particles (electrons with energy 15 keV to several MeV and ions with energy > 30 keV) from the dusk side of the magnetosphere. The dual spacecraft measurements show clearly that magnetospheric particles leak directly into the interplanetary medium from the closed magnetosphere, and are the source for the “upstream” particle events [Baker et al., 1996; Zwickl et al., 1981; Krimigis, 1992; Haggerty and Armstrong, 1999; Anagnostopoulos et al., 1998] that have been reported from instruments during prior single spacecraft encounters with the planet. These events, consisting of high-energy particles of Jovian origin, have been observed throughout the heliosphere [Baker and Van Allen, 1976] and their propagation has recently been modeled [Fichtner et al., 2000; Ferreira et al., 2001]. Jupiter then is an important contributor to the interplanetary charged particle fluxes, especially within an astronomical unit of the planet. |
Lanzerotti, L. J., S. M. Krimigis, R. B. Decker, S. E. Hawkins, III, R. E. Gold, E. C. Roelof, T. P Armstrong, Low-Energy Particles in the Global Heliosphere 2001-2004: 1 to 90 AU, Space Sci. Rev., 243-248, 2001. Journal abstract, with link to full article.
| Abstract (draft). Charged particle instrumentation that will be flying on six spacecraft in the heliosphere between 1 and 20 AU during 2001-2004 will provide a global view of the interplanetary medium that has not heretofore been available. Comparative analyses of the data that will be obtained will provide new understanding of the global evolution of heliospheric features such as traveling shock waves, coronal mass ejections, solar activity-produced particle injections, and anomalous cosmic rays. |
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Updated 7/31/07, T. Hunt-Ward
tizby@ftecs.com