نوع مقاله : مقاله پژوهشی

نویسنده

گروه فیزیک، دانشکده علوم پایه، دانشگاه گنبد کاووس، صندوق پستی: 163، گنبد کاووس - ایران

چکیده

در این مقاله انتشار امواج غیرخطی یون- صوتی در یک پلاسمای برخوردی با حضور الکترون­های فوق­حرارتی با تابع توزیع کاپا مطالعه شده است. با نوشتن معادلات سیالی برای یون­ها و لحاظ کردن سهم برخورد بین یون­ها با اتم­های خنثی و هم­چنین به­کار بردن روش اختلال کاهشی، معادله غیرخطی تعمیم­یافته کورته وگ- ده وری (K-dV) تعیین شده است. نتایج نشان­دهنده انتشار پالس الکتریکی با دامنه مثبت (امواج سالیتونی متراکم) است. بررسی‌های عددی نشان می‌دهند که برخورد یون­ها با اتم­های خنثی تأثیر ویژه‌ای بر ساختار امواج یون- صوتی دارند. به­عبارت دیگر، با افزایش فرکانس برخورد دامنه (پهنای) موج یون- صوتی کاهش (افزایش) می‌یابد. علاوه براین، اثر شاخص طیفی الکترون­های فوق­حرارتی و دمای یون­ها نیز بر ساختار این امواج مورد بررسی قرار گرفته است.

کلیدواژه‌ها

عنوان مقاله [English]

Influence of ion-neutral collisional frequency and Kappa spectral index on dynamics of nonlinear ion-acoustic waves in superthermal plasmas

نویسنده [English]

  • M. Mehdipoor

Department of Physics, Faculty of Science, Gonbad Kavous University, P.O.Box: 163, Gonbad Kavous - Iran

چکیده [English]

In the present work, the propagation of nonlinear ion-acoustic waves is studied in a collisional plasma with superthermal electrons with a Kappa distribution function. Considering the basic set of fluid equations and the ion-neutral collisions, a modified nonlinear Korteweg-de Vries (K-dV) equation is derived by using the reductive perturbation method. It was found that only compressive ion-acoustic solitary waves can be propagated in this model. Also, the numerical results show that the ion-neutral collisions have significant effects on solitary wave structures. In other words, the amplitude (width) of the ion-acoustic solitons decreases (increases) with the increasing of the ion-neutral collision frequency. Moreover, the effects of the spectral index of superthermal electrons and ion temperature on the ion-acoustic solitons are also studied in the present plasma model.

کلیدواژه‌ها [English]

  • Ion-acoustic waves
  • Collisional plasma
  • Superthermal electrons
  • Reductive perturbation method
  • Modified K-dV equation
1. H. Ikezi, R. Taylor, D. Baker, Formation and Interaction of Ion-Acoustic solitons, Phys. Rev. Lett. 25, 11 (1970).
 
2.             H. Washimi, T. Taniuti, Propagation of Ion-Acoustic Solitary Waves of Small Amplitude, Phys. Rev. Lett. 17, 996 (1966).
 
3.             R.Z. Sagdeev, Cooperative Phenomena and Shock Waves in Collisionless Plasmas, Rev. Plasma Phys. 4, 23 (1966).
 
4.             B. Bhattacharyya, Dominance of ion motion over electron motion in some intensity-induced wave processes in a magnetized plasma, Phys. Rev. A. 27, 1 (1983).
 
5.             V.M. Vasyliunas, A survey of low-energy electrons in the evening sector of the magnetosphere with OGO 1 and OGO 3, J. Geophys. Res. 73, 2839 (1968).
 
6.             V. Pierrard, J. Lemaire, Lorentzian ion exosphere model,  J. Geophys. Res. 101, 7923 (1996).
 
7.             S.P. Christon, et al. Energy spectra of plasma sheet ions and electrons from ∼50 eV/e to ∼1 MeV during plasma temperature transitions, J. Geophys. Res. 93, 2562 (1988).
 
8.             M. Maksimovic, V. Pierrard, P. Riley, Ulysses electron distributions fitted with Kappa functions, Geophys. Res. Lett. 24, 1151 (1997).
 
9.             M. Krimigis, et al, General characteristics of hot plasma and energetic particles in the Saturnian magnetosphere: Results from the Voyager spacecraft, J. Geophys. Res. 88, 8871 (1983).
 
10. V. Pierrard, H. Lamy, J. Lemaire, Exospheric distributions of minor ions in the solar wind, J. Geophys. Res. 109, A02118 (2004).
 
11. M.P. Leubner, Fundamental issues on kappa-distributions in space plasmas and interplanetary proton distributions, Phys. Plasmas, 11, 1308 (2004).
 
12.          M.A. Hellberg, et al, Electron-acoustic waves in the laboratory: an experiment revisited, J. Plasma Phys. 64, 433 (2000).
 
13.          T.K. Baluku, M.A. Hellberg, Dust acoustic solitons in plasmas with kappa-distributed electrons and/or ions, Phys. Plasmas, 15, 123705 (2008).
 
14.          N.S. Saini, I. Kourakis, M.A. Hellberg, Arbitrary amplitude ion-acoustic solitary excitations in the presence of excess superthermal electrons, Phys. Plasmas, 16, 062903 (2009).
 
15.          S. Sultana, et al, Oblique electrostatic excitations in a magnetized plasma in the presence of excess superthermal electrons, Phys. Plasmas, 17, 032310 (2010).
 
16. Y.D. Jung, W.P. Hong, Nonthermal effects on the ion-acoustic solitons in Lorentzian electron-ion plasmas, Phys. Plasmas, 18, 024502 (2011).
 
17.          B.N. Goswami, B. Buti, Ion acoustic solitary waves in a two-electron-temperature plasma, Phys. Lett. A. 57, 149 (1976).
 
18. G.C. Das, S.N. Paul, B. Karmakar, Ion‐acoustic solitary waves in two‐temperature electron plasmas, Phys. Fluids, 29, 2192 (1986).
 
19.          S.S. Ghosh, K.K. Ghosh, A.N.I. Sekar, Large Mach number ion acoustic rarefactive solitary waves for a two electron temperature warm ion plasma, Phys. Plasmas, 3, 3939 (1996).
 
20.          O.R. Rufai, et al, Low frequency solitons and double layers in a magnetized plasma with two temperature electrons, Phys. Plasmas, 19, 122308 (2012).
 
21.          D.D. Barbosa, W.S. Kurth, On the generation of plasma waves in Saturn's inner magnetosphere, J. Geophys. Res. 98, 9351 (1993).
 
22.          E.C. Sittler, Jr.K.W. Ogilive, J.D. Scudder, Survey of low-energy plasma electrons in Saturn's magnetosphere: Voyagers 1 and 2,  J. Geophys. Res. 88, 8847 (1983).
 
23.          P. Schippers, et al, Multi-instrument analysis of electron populations in Saturn's magnetosphere, J. Geophys. Res. 113, A07208 (2008).
 
24.          T.K. Baluku, M.A. Hellberg, Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons, Phys. Plasmas, 19, 012106 (2012).
 
25.          F. Verheest, M.A. Hellberg, I. Kourakis, Ion-acoustic supersolitons in plasmas with two-temperature electrons: Boltzmann and kappa distributions, Phys. Plasmas, 20, 082309 (2013).
 
26.          N.S. Saini, et al, Zakharov-Kuznetsov equation in a magnetized plasma with two temperature superthermal electrons, Phys. Plasmas, 21, 022114 (2014).
 
27. S. Ghosh, A. Adak, M. Khan, Dissipative solitons in pair-ion plasmas, Phys. Plasmas, 21, 012303 (2014).
28. S. Sultana, Ion acoustic solitons in magnetized collisional non-thermal dusty plasmas, Phys. Lett. A 382, 1368–1373 (2018).
 
29. S. Sultana, Dissipative high-frequency envelope soliton modes in nonthermal plasmas, Phys. Rev. E, 98, 033207 (2018).
 
30. A. Adak, S. Ghosh, N. Chakrabarti, Ion acoustic shock wave in collisional equal mass plasma, Phys. Plasmas, 22, 102307 (2015).
 
31.          I.S. Elkamash, I. Kourakis, Electrostatic shock structures in dissipative multi-ion dusty plasmas, Phys. Plasmas, 25, 062104 (2018).
 
32.          J. Vranjes, P.S. Krstic, Collisions, magnetization, and transport coefficients in the lower solar atmosphere, Astron. Astrophys. 554, 22–32 (2013).
 
33.          V.I. Karpman, E.M. Maslov, Perturbation Theory for Solitons, Sov. Phys. JETP, 46, 2 (1977).
 
34.          R.L. Herman, A direct approach to studying soliton perturbations, J. Phys. A. 23, (1990).