ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-32-1025-2014 Ion dynamics in electron beam–plasma interaction: particle-in-cell simulations Baumgärtel K. 1 Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany 22 08 2014 32 8 1025 1033 Copyright: © 2014 K. Baumgärtel 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/32/1025/2014/angeo-32-1025-2014.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/32/1025/2014/angeo-32-1025-2014.pdf

Electron beam–plasma interaction including ions is studied by particle-in-cell (PIC) simulations using a one-dimensional, electrostatic code. Evidence for Langmuir wave decay is given for sufficiently energetic beams, as in previous Vlasov–Maxwell simulations. The mechanism for the generation of localized finite-amplitude ion density fluctuations is analyzed. Amplitude modulation due to interference between the beam-generated Langmuir waves causes random wave localization including strong transient spikes in field intensity which create bursty ion density structures via ponderomotive forces. More dense beams may quench the decay instability and generate low-frequency variations dominated by the wave number of the fastest growing Langmuir mode.

 References Akimoto, K., Omura, Y., and Natsumoto, H.: Rapid generation of Langmuir wave packets during electron beam–plasma instabilities, Phys. Plasmas, 3, 2559–2563, 1996. Bale, S. D., Burgess, D., Kellog, P. I., Goetz, K., Howard, R. L., and Monson, S. J.: Phase coupling in Langmuir wave packets: Possible evidence of three–wave interactions in the upstreqm solar wind, Geophys. Res. Lett., 23, 109–112, 1996. Baumgärtel, K.: Coherent amplitude modulation of electron-beam-driven Langmuir waves, Ann. Geophys., 31, 633–638, <a href="http://dx.doi.org/10.5194/angeo-31-633-2013">https://doi.org/10.5194/angeo-31-633-2013</a>, 2013. Cairns, I. H. and Melrose, D. B.: A theory for the 2fp radiation upstream of Earths bow shock, J. Geophys. Res., 90, 6637–6640, 1985. Cairns, I. H. and Robinson, P. A.: Ion acoustic wave frequencies and onset times during type II solar radio bursts, Astrophys. J., 453, 959–972, 1995. Daldorff, L. K. S., Pecseli, H. L., Trulsen, J. K., Ulriksen, M. I., Eliasson, B., and Stenflo, L.: Nonlinear beam generated plasma waves as a source for enhanced plasma and ion acoustic lines, Phys. Plasmas, 18, 052107, <a href="http://dx.doi.org/10.1063/1.3582084">https://doi.org/10.1063/1.3582084</a>, 2011. Ergun, R. E., Malaspina, D. M., Cairns, I. H., Goldman, M. V., Newman, D. L., Robinson, P. A., Ericsson, S., Bougeret, J. L., Briand, C., Bale, S. D., Cattell, C. A., Kellogg, P. J., and Kaiser, M. L.: Eigenmode structure in solar–wind Langmuir waves, Phys. Rev. Lett., 101, 051101, <a href="http://dx.doi.org/10.1103/PhysRevLett.101.051101">https://doi.org/10.1103/PhysRevLett.101.051101</a>, 2008. Graham, D. B. and Cairns, I. H.: Electrostatic decay of Langmuir/z–mode waves in type III solar radio bursts, J. Geophys. Res., 118, 3968–3984, <a href="http://dx.doi.org/10.1002/jgra.50402">https://doi.org/10.1002/jgra.50402</a>, 2013a. Graham, D. B. and Cairns, I. H.: Constraints on the formation and structure of Langmuir eigenmodes in the solar wind, Phys. Rev. Lett., 111, 121101, <a href="http://dx.doi.org/10.1103/PhysRevLett.111.121101">https://doi.org/10.1103/PhysRevLett.111.121101</a>, 2013b. Gurnett, D. A., Maggs, J. E., Gallagher, D. L., Kuhrt, W. S., and Scarf, F. L.: Parametric interaction and spatial collapse of beam–driven Langmuir waves in the solar wind, J. Geophys. Res., 86, 8833–8841, 1981. Gurnett, D. A., Hospodarsky, G. B., Kurth, W. S., Williams, D. J., and Bolton, S. J.: Fine structure of Langmuir waves produced by a solar electron event, J. Geophys. Res., 98, 5631–5637, 1993. Hospodarsky, G. R., Gurnett, D. A., Kurth, S. W., Kivelson, M. G., Strangeway, R. J., and Bolton, S. J.: Fine structure of Langmuir waves observed upstream of the bow shock at Venus, J. Geophys. Res., 99, 13363–13371, 1994. Hospodarsky, G. R. and Gurnett, D. A.: Beat–type Langmuir wave emissions associated with a type III solar radio burst: Evidence of parametric decay, Geophys. Res. Lett., 22, 1161–1164, 1995. Kellog, P. I., Monson, S. J., Goetz, K., Howard, R., Bougeret, J. L., and Kaiser, M. L.: Early wind observations of bow shock and foreshock waves, Geophys. Res. Lett., 23, 1243–1246, 1996. Kellog, P. I., Goetz, K., Monson, S. J., and Opitz, A.: Observations of transverse Z mode and parametric decay in the solar wind, J. Geophys. Res., A118, 4766–4775, 2013. Kojima, H., Furuya, H., Usui, H., and Matsumoto, H.: Modulated electron plasma waves observed in the tail lobe: Geotail waveform observations, Geophys. Res. Lett., 24, 3049–3052, 1997. Langdon, A. B.: Implicit plasma simulations, Space Sci. Rev., 42, 67–83, 1985. Layden, A., Cairns, I. H., Li, B., and Robinson, P. A.: Electrostatic decay in a weakly magnetized plasma, Phys. Rev. Lett., 110, 185001, <a href="http://dx.doi.org/10.1103/PhysRevLett.110.185001">https://doi.org/10.1103/PhysRevLett.110.185001</a>, 2013. Lin, R. P., Levedahl, W. K., Lotko, W., Gurnett, D. A., and Scarf, F. L.: Evidence for nonlinear wave–wave interactions in solar type III radio bursts, Astrophys. J., 308, 954–965, 1986. Malaspina, D. M., Cairns, I. H., and Ergun, R. E.: Dependence of Langmuir wave polarization on electron beam speed in type II solar radio bursts, Geophys. Res. Lett., 38, L13101, <a href="http://dx.doi.org/10.1029/2011GL047642">https://doi.org/10.1029/2011GL047642</a>, 2011. Matsukiyo, S., Treumann, R. A., and Scholer, M.: Coherent waveforms in the auroral upward current region, J. Geophys. Res., 109, A06212, <a href="http://dx.doi.org/10.1029/2004JA010477">https://doi.org/10.1029/2004JA010477</a>, 2004. Muschietti, L., Roth, I., and Ergun, R. E.: On the formation of wave packets in planetary foreshocks, J. Geophys. Res., 101, 15605–15613, 1996. \bibitem [Omura et al., 1996]Omura96 Omura, Y., Matsumoto, H., Miyake, T., and Kojima, H.: Electron beam instabilities as generation mechanism of electrostatic solitary waves in the magnetotail, J. Geophys. Res., 101, 2685–2697, 1996. Pottelette, R., Ergun, R. E., Treumann, R. A., Berthomier, M., Carlson, C. W., McFadden, J. P., and Roth, I.: Modulated electron–acoustic waves in auroral density cavities: Fast observations, Geophys. Res. Lett., 26, 2629–2632, 1999. Robinson, P. A., Willes, A. J., and Cairns, I. H.: Dynamics of Langmuir and ion–sound waves in type III solar radio sources, Astrophys. J., 408, 720–734, 1993. Sauer, K. and Sydora, R.: Mode crossing effects at electron beam–plasma interaction and related phenomena, Plasma Phys. Control. Fusion, 54, 124054, <a href="http://dx.doi.org/10.1088/0741-3335/54/12/124045">https://doi.org/10.1088/0741-3335/54/12/124045</a>, 2012. Sigsbee, K., Kletzing, C. A., Pickett, J. S., Gurnett, D. A., Schwartz, S. J., Levebvre, B., Lucek, E., Fazakerley, A. N., and Kucharek, H.: Characteristics of Langmuir electric field waveforms and power spectra exhibiting nonlinear behavior in Earth's foreshock, J. Geophys. Res., 115, A10251, <a href="http://dx.doi.org/10.1029/2009JA014948">https://doi.org/10.1029/2009JA014948</a>, 2010. Silin, I., Sydora, R., and Sauer, K.: Electron beam–plasma interaction: Linear theory and Vlasov–Poisson simulations, Phys. Plasmas, 14, 012106, <a href="http://dx.doi.org/10.1063/1.2430518">https://doi.org/10.1063/1.2430518</a>, 2007. Stasiewicz, K., Holback, B., Krasnoselskikh, V., Boehm, M., Boström, R., and Kintner, P. M.: Parametric instabilities of Langmuir waves observed by Freija, J. Geophys. Res., 101, 21515–21525, 1996. \bibitem[Thejappa et al., 2013] Thejappa113 Thejappa, G., MacDowall, R. J., and Bergamo, M.: Evidence for four- and three-wave interactions in solar type III radio emissions, Ann. Geophys., 31, 1417–1428, <a href="http://dx.doi.org/10.5194/angeo-31-1417-2013">https://doi.org/10.5194/angeo-31-1417-2013</a>, 2013. Umeda, T.: Vlasov simulation of amplitude modulated Langmuir waves, Phys. Plasmas, 13, 092304, <a href="http://dx.doi.org/10.1063/1.2348088">https://doi.org/10.1063/1.2348088</a>, 2006. Umeda, T.: Vlasov simulation of Langmuir wave packets, Nonlin. Processes Geophys., 14, 671–679, <a href="http://dx.doi.org/10.5194/npg-14-671-2007">https://doi.org/10.5194/npg-14-671-2007</a>, 2007. Umeda, T. and Ito, T.: Vlasov simulation of Langmuir decay instability, Phys. Plasmas, 15, 084503, <a href="http://dx.doi.org/10.1063/1.2965494">https://doi.org/10.1063/1.2965494</a>, 2008. Usui, H., Furuya H., Kojima, H., Matsumoto, H., and Omura, Y: Computer experiments of amplitude–modulated Langmuir waves: Application to Geotail observation, J. Geophys. Res., 110, A06203, <a href="http://dx.doi.org/10.1029/2004JA010703">https://doi.org/10.1029/2004JA010703</a>, 2005.