Freak waves in Saturn’s magnetosphere
- 139 Downloads
Properties of planar as well as nonplanar ion acoustic freak waves that propagate in a plasma composed of warm ions and two-temperature electron plasma having kappa-distribution are reported. The dynamics of the nonlinear freak waves is governed by a modified nonlinear Schrödinger equation. The possible region for the freak waves to exist is defined precisely for typical parameters of Saturn’s magnetosphere. For planar case, stability/instability analyses reveals that there is a critical value (f cr ) of f (i.e., the equilibrium density ratio of the hot-to-cold electron species) exists for low wave number k. For large wave number k, the stability domain is always a decreasing function in f. Low κ values, which indicate that an excess of suprathermal particles in the tail of the distribution, shifts f cr to higher values. Also, there exists a modulation instability period for the cylindrical and spherical envelope excitations, which does not exist in the one-dimensional case. Furthermore, cylindrical and spherical freak waves are investigated numerically. Spherical ion-acoustic freak waves are found to grow faster than the cylindrical waves.
KeywordsNonlinear wave modulation Cylindrical and spherical rogue waves Ion-acoustic wavepackets Saturn’s magnetosphere Super-thermal electron distribution
The author dedicate this work to the memory of Prof. Padma Kant Shukla.
- Lazar, M., Schlickeiser, R., Poedts, S., Tautz, R.C.: Mon. Not. R. Astron. Soc. 168, 390 (2008) Google Scholar
- Young, D.T., Berthelier, J.J., Blanc, M., Burch, J.L., Bolton, S., Coates, A.J., Crary, F.J., Goldstein, R., Grande, M., Hill, T.W., Johnson, R.E., Baragiola, R.A., Kelha, V., McComas, D.J., Mursula, K., Sittler, E.C., Svenes, K.R., Szego, K., Tanskanen, P., Thomsen, M.F., Bakshi, S., Barraclough, B.L., Bebesi, Z., Delapp, D., Dunlop, M.W., Gosling, J.T., Furman, J.D., Gilbert, L.K., Glenn, D., Holmlund, C., Illiano, J.M., Lewis, G.R., Linder, D.R., Maurice, S., McAndrews, H.J., Narheim, B.T., Pallier, E., Reisenfeld, D., Rymer, A.M., Smith, H.T., Tokar, R.L., Vilppola, J., Zinsmeyer, C.: Science 307, 1262 (2005) ADSCrossRefGoogle Scholar