Abstract
Using a 2 1/2-D fully relativistic electromagnetic particle-in-cell code (PIC) we have investigated a potential electron acceleration mechanism in solar flares. The free energy is provided by ions which have a ring velocity distribution about the magnetic field direction. Ion rings may be produced by perpendicular shocks, which could in turn be generated by the super-Alfvénic motion of magnetic flux tubes emerging from the photosphere or by coronal mass ejections (CMEs). Such ion distributions are known to be unstable to the generation of lower hybrid waves, which have phase velocities in excess of the electron thermal speed parallel to the field and can, therefore, resonantly accelerate electrons in that direction. The simulations show the transfer of perpendicular ion energy to energetic electrons via lower hybrid wave turbulence. With plausible ion ring velocities, the process can account for the observationally inferred fluxes and energies of non-thermal electrons during the impulsive phase of flares. Our results also show electrostatic wave generation close to the plasma frequency: we suggest that this is due to a bump-in-tail instability of the electron distribution.
Similar content being viewed by others
References
Antonucci, E., Gabriel, A. H., Acton, L. W., Culhane, J. L., Doyle, J. G., Leibacher, J. W., Machado, M. E., Orwig, L. E., and Rapley, C. G.: 1982, Solar Phys. 78, 107.
Biskamp, D.: 1973, Nucl. Fusion 13, 719.
Boldt, E. and Serlemitsos, P.: 1969, Astrophys. J. 157, 557.
Brown, J. C.: 1971, Solar Phys. 18, 489.
Brown, J. C., Melrose, D. B., and Spicer, D. S.: 1979, Astrophys. J. 228, 592.
Burgess, D., Wilkinson, W. P., and Schwartz, S. J.: 1989, J. Geophys. Res. 94, 8783.
Canfield, R. C., Bely-Dubau, F., Brown, J. C., Dulk, G. A., Emslie, A. G., Enome, S., Gabriel, A. H., Kundu, M. R., Melrose, D., Neidig, D. F., Ohki, K., Petrosian, V., Poland, A., Rieger, E., Tanaka, K., and Zirin, H.: 1986, in M. R. Kundu and B. Woodgate (eds.), Energetic Phenomena on the Sun, NASA CP-2439, Ch. 3.
Edmiston, J. P. and Kennel, C. F.: 1984, J. Plasma Phys. 32, 429.
Emslie, A. G. and Alexander, D.: 1987, Solar Phys. 110, 295.
Harrison, R. A.: 1986, Astron. Astrophys. 162, 283.
Heyvaerts, J., Priest, E. R., and Rust, D. M.: 1977, Astrophys. J. 216, 123.
Hildner, E., Bassi, J., Bougeret, J. L., Duncan, R. A., Gary, D. E., Gergely, T. E., Harrison, R. A., Howard, R. A., Illing, R. M. E., Jackson, B. V., Kahler, S. W., Kopp, R., Low, B. C., Lantos, P., Phillips, K. J. H., Poletto, G., Sheeley, N. R., Stewart, R. T., Švestka, Z., Waggett, P. W., and Wu, S. T.: 1986, in M. R. Kundu and B. Woodgate (eds.), Energetic Phenomena on the Sun, NASA CP-2439, Ch. 6.
Holman, G. D.: 1985, Astrophys. J. 293, 584.
Hoyng, P., Brown, J. C., and van Beek, H. F.: 1976, Solar Phys. 48, 197.
Hsia, J. B., Chiu, S. M., Hsia, M. F., Chou, R. L., and Wu, C. S.: 1979, Phys. Fluids 22, 1737.
Krall, N. A. and Liewer, P. C.: 1971, Phys. Rev. A4, 2094.
Lampe, M., and Papadopoulos, K.: 1977, Astrophys. J. 212, 886.
Leroy, M. M., Goodrich, C. C., Winske, D., Wu, C. S., and Papadopoulos, K.: 1981, Geophys. Res. Letters 8, 1269.
McBride, J. B., Ott, E., Boris, J. P., and Orens, J. H.: 1972, Phys. Fluids 15, 2367.
Melrose, D. B.: 1980, Plasma Astrophysics, Vol. 2, Gordon and Breach, New York.
Melrose, D. B. and Kuijpers, J.: 1987, Astrophys. J. 323, 338.
Papadopoulos, K.: 1981, Proc. 1st Int. School Plasma Ap., ESA SP-161, p. 313.
Paschmann, G., Sckopke, N., Bame, S. J., and Gosling, J. T.: 1982, Geophys. Res. Letters 9, 881.
Phillips, P. E. and Robson, A. E.: 1972, Phys. Rev. Letters 29, 154.
Smith, D. F.: 1980, Solar Phys. 66, 135.
Smith, D. F. and Lilliequist, C. G.: 1979, Astrophys. J. 232, 582.
Spicer, D. S.: 1977, Solar Phys. 53, 305.
Spicer, D. S.: 1982, Space Sci. Rev. 31, 351.
Spicer, D. S. and Emslie, A. G.: 1988, Astrophys. J. 330, 997.
Spicer, D. S., Benz, A. O., and Huba, J. D.: 1981, Astron. Astrophys. 105, 221.
Takakura, T. and Kai, K.: 1966, Publ. Astron. Soc. Japan 18, 57.
Thejappa, G.: 1987, Solar Phys. 111, 45.
Tidman, D. A. and Krall, N. A.: 1971, Shock Waves in Collisionless Plasma, Wiley, New York.
Tsytovich, V. N., Stenflo, L., and Wilhelmson, H.: 1975, Phys. Scripta 11, 251.
Vlahos, L., Gergely, T. E., and Papadopoulos, K.: 1982, Astrophys. J. 258, 812.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
McClements, K.G., Su, J.J., Bingham, R. et al. Simulation studies of electron acceleration by ion ring distributions in solar flares. Sol Phys 130, 229–241 (1990). https://doi.org/10.1007/BF00156791
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00156791