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Ion-Acoustic Instabilities in a Multi-Ion Plasma

DOI: 10.1155/2013/838534

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We have, in this paper, studied the stability of the ion-acoustic wave in a plasma composed of hydrogen, positively and negatively charged oxygen ions, and electrons, which approximates very well the plasma environment around a comet. Modelling each cometary component ( , , and ) by a ring distribution, we find that ion-acoustic waves can be generated at frequencies comparable to the hydrogen ion plasma frequency. The dispersion relation has been solved both analytically and numerically. We find that the ratio of the ring speed ( ) to the thermal spread ( ts) modifies the dispersion characteristics of the ion-acoustic wave. The contrasting behaviour of the phase velocity of the ion-acoustic wave in the presence of ions for ts (and vice versa) can be used to detect the presence of negatively charged oxygen ions and also their thermalization. 1. Introduction Low-frequency electrostatic or longitudinal ion density waves are one of the most fundamental of oscillations in a plasma [1, 2]. In the long-wavelength limit, the ions provide the inertia with the electrons as the source of the restoring force [1]. Ion-acoustic waves also exhibit strong nonlinear properties and are highly Landau damped unless , where and are, respectively, the ion and electron temperatures [3–5]. These waves have been observed in both space and laboratory plasmas; they have thus been extensively studied in many types of high-temperature laboratory plasmas [4, 6]. The waves have been invoked to explain wave characteristics observed in Earth’s ionosphere [7] and transport in the solar wind, corona, chromosphere [8], and comets [9]. In general a cometary environment contains new born hydrogen and heavier ions, with relative densities depending on the distance from the nucleus. Previous studies have concentrated on positively charged oxygen as the heavier ion species [10]. However, Giotto’s observations of the inner coma of comet Halley showed that a new component, namely, negatively charged cometary ions was present, in addition to the usual thermal electrons and ions, fast cometary pickup ions, and so forth, [11]. These negative ions were observed in three broad mass peaks at 7–19, 22–65, and 85–110 amu with being identified unambiguously [11]. A popular model of a cometary environment is the solar wind plasma environment permeated by dilute, drifting ring distribution of electrons and ions with finite thermal spreads [10]. Instabilities driven by an electron velocity ring distributions have been studied by many authors [12–14]. However, ion ring distributions are more important


[1]  J. Castro, P. McQuillen, and T. C. Killian, “Ion acoustic waves in ultracold neutral plasmas,” Physical Review Letters, vol. 105, no. 6, Article ID 065004, 2010.
[2]  L. Tonks and I. Langmuir, “Oscillations in ionized gases,” Physical Review, vol. 33, no. 2, pp. 195–210, 1929.
[3]  T. H. Stix, Waves in Plasmas, American Institute of Physics, New York, NY, USA, 2nd edition, 1992.
[4]  Y. Nakamura, H. Bailung, and P. K. Shukla, “Observation of ion-acoustic shocks in a dusty plasma,” Physical Review Letters, vol. 83, no. 8, pp. 1602–1605, 1999.
[5]  Z. Liu, L. Liu, and J. Du, “A nonextensive approach for the instability of current-driven ion-acoustic waves in space plasmas,” Physics of Plasmas, vol. 16, no. 7, Article ID 072111, 5 pages, 2009.
[6]  M. Yamada and M. Raether, “Saturation of the ion-acoustic instability in a weakly ionized plasma,” Physical Review Letters, vol. 32, no. 3, pp. 99–102, 1974.
[7]  M. E. Koepke, “Contributions of Q-machine experiments to understanding auroral particle acceleration processes,” Physics of Plasmas, vol. 9, no. 5, pp. 2420–2427, 2002.
[8]  S. R. Cranmer, A. A. Van Ballegooijen, and R. J. Edgar, “Self-consistent coronal heating and solar wind acceleration from anisotropic magnetohydrodynamic turbulence,” Astrophysical Journal, Supplement Series, vol. 171, no. 2, pp. 520–551, 2007.
[9]  F. L. Scarf, F. V. Coroniti, C. F. Kennel, D. A. Gurnett, W.-H. Ip, and E. J. Smith, “Plasma wave observations at comet Giacobini-Zinner,” Science, vol. 232, no. 4748, pp. 377–381, 1986.
[10]  A. L. Brinca and B. T. Tsurutani, “Unusual characteristics of electromagnetic waves excited by cometary newborn ions with large perpendicular energies,” Astronomy & Astrophysics, vol. 187, no. 1-2, pp. 311–319, 1987.
[11]  P. Chaizy, H. Rème, J. A. Sauvaud et al., “Negative ions in the coma of comet Halley,” Nature, vol. 349, no. 6308, pp. 393–396, 1991.
[12]  T. J. Tataronis and F. Crawford, “Cyclotron harmonic wave propagation and instabilities,” Journal of Plasma Physics, vol. 4, no. 2, pp. 231–264, 1970.
[13]  M. Ashour-Abdalla and C. F. Kennel, “Nonconvective and convective electron cyclotron harmonic instabilities,” Journal of Geophysical Research, vol. 83, p. 1531, 1978.
[14]  P. Sprangle, J. L. Vomvoridis, and W. M. Manheimer, “A classical electron cyclotron quasioptical maser,” Applied Physics Letters, vol. 38, no. 5, pp. 310–313, 1981.
[15]  K. Akimoto, K. Papadopoulos, and D. Winske, “Ion-acoustic instabilities driven by an ion velocity ring,” Journal of Plasma Physics, vol. 34, no. 3, pp. 467–479, 1985.
[16]  J. A. Byers and M. Grewal, “Perpendicularly propagating plasma cyclotron instabilities simulated with a one-dimensional computer model,” Physics of Fluids, vol. 13, no. 7, pp. 1819–1830, 1970.
[17]  J. K. Lee and C. K. Birdsall, “Velocity space ring-plasma instability, magnetized, part I: theory,” Physics of Fluids, vol. 22, no. 7, pp. 1306–1314, 1979.
[18]  S. Seiler, M. Yamada, and H. Ikezi, “Lower hybrid instability driven by a spiraling ion beam,” Physical Review Letters, vol. 37, no. 11, pp. 700–703, 1976.
[19]  H. E. Mynick, M. J. Gerver, and C. K. Birdsall, “Stability regions and growth rates for a two-ion component plasma, unmagnetized,” Physics of Fluids, vol. 20, no. 4, pp. 606–612, 1977.
[20]  C. Cattel and M. Hudson, “Flute mode waves near ωLH excited by ion rings in velocity space,” Geophysical Research Letters, vol. 9, no. 10, pp. 1167–1170, 1982.
[21]  K. Akimoto, K. Papadopoulos, and D. Winske, “Lower-hybrid instabilities driven by an ion velocity ring,” Journal of Plasma Physics, vol. 34, no. 3, pp. 445–465, 1985.
[22]  F. Scarf, “Plasma wave observations at comets Giacobini-Zinner and Halley,” in Plasma Waves and Instabilities at Comets and in Magnetospheres, B. T. Tsurutani and H. Oya, Eds., American Geophysical Union, Washington, DC, USA, 1989.
[23]  R. C. Davidson, “Kinetic waves and instabilities in a uniform plasma,” in Basic Plasma Physics, A. Galeev and R. Sudan, Eds., North-Holland, New York, NY, USA, 1989.
[24]  B. D. Fried and S. D. Conte, The Plasma Dispersion Function, Academic Press, New York, NY, USA, 1961.
[25]  D. A. Gurnnet and A. Bhattacharjee, Introduction to Plasma Physics: with Space and Laboratory Applications, Cambridge University Press, Cambridge, UK, 1st edition, 2005.
[26]  J. D. Gaffey Jr, D. Winske, and C. S. Wu, “Time scales for formation and spreading of velocity shells of pickup ions in the solar wind,” Journal of Geophysical Research, vol. 93, no. A6, pp. 5470–5486, 1988.
[27]  A. P. Misra, N. C. Adhikary, and P. K. Shukla, “Ion-acoustic solitary waves and shocks in a collisional dusty negative-ion plasma,” Physical Review E, vol. 86, no. 5, Article ID 056406, 10 pages, 2012.
[28]  S. H. Kim and R. L. Merlino, “Charging of dust grains in a plasma with negative ions,” Physics of Plasmas, vol. 13, no. 5, Article ID 052118, 7 pages, 2006.
[29]  M. Rosenberg and R. L. Merlino, “Ion-acoustic instability in a dusty negative ion plasma,” Planetary and Space Science, vol. 55, no. 10, pp. 1464–1469, 2007.


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