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Multi-ion plasma is found in many regions of space like the earth's ionosphere, mesosphere, solar atmosphere, commentary environments, etc. Of this commentary plasma is of particular interest among researchers due to the presence of a wide variety of many species of ions: besides electrons and protons of solar origin, photoionization causes the production of H + and O + from water molecules present in the commentary atmosphere in addition to the associated photo-electrons [1]. Also, several positively charged hot lighter and heavier ions have been observed at comet Halley [2-5]. Further, the observation of negatively charged ions by spacecraft Giotto with energies between 0.03 to 3.0 keV and mass peaks in the range 7-19, 22-65 and 85-110 amu in comet Halley gave a new dimension to the investigations on plasma where negatively charged ion species act as an ion pair [6]. Later, many investigations were done where both positively and negatively charged dust particles coexist in the same plasma environment [7] in which former would be smaller and latter would be larger in size [8]. In recent decade, there were extensive studies on different nonlinear propagations of waves in different plasma environments [9-14]. This includes plasmas with cold dust and electrons and/or ions described by kappa distribution functions [15] and cold dust, adiabatic fluid ions and kappa described electrons [16]. Photo-ionization in commentary plasma environments causes the production of photo-electrons which in turn act as a major second electron component, apart from the typical solar hot electrons. For example, Zwickl et al. [17] , observed such photo-electrons from photo-ionization of commentary neutrals at comet Giacobini-Zinner by the electron spectrometer on the spacecraft ICE. Also, Bhardwaj observed the production of energetic photo-electrons in a study related to the gas production rates in comets [18]. It is a fact that the presence of high energetic particles in plasma deviate from typical Maxwellian to a non Maxwellian type "kappa distribution". Such a kind of distribution was first predicted by Vasyliunas using energetic solar wind data [19] ; this distribution has since been used to model a number of space and astrophysical environments. We, therefore study the characteristics of dust ion-acoustic solitary waves in this five component plasma, in which the electrons are modeled by kappa distributions. We find that different heavier ions significantly affect the amplitude and width of the solitary waves. BASIC EQUATIONS We are interested in solitary waves in five component plasma. The heavier ions (dust) and lighter (hydrogen) ion components ABSTRACT We investigate the influence of ions of different masses on oblique solitary waves in five component plasma consisting of positively and negatively charged heavier ions (dust), hydrogen ions and hotter and colder electrons. Of these, the heavier ions and colder photo-electrons are of commentary origin while the other two are of solar origin; the electrons being described by kappa ...

The stability of the kinetic Alfven wave (KAW) has been studied in a plasma composed of electrons, hydrogen and positively and negatively charged oxygen ions. Using the two potential theory of Hasegawa, we have derived an expression for the frequency and growth/damping rate of the KAW. The dispersion relation derived in this paper is a generalization of the dispersion relation of Hasegawa on two counts: (i) we use a more generalized distribution function and show that our relation reduces to the dispersion relation of Hasegawa in the limiting case, and (ii) it is applicable to a multi-ion plasma containing lighter ions and positively and negatively charged heavier ions. We find the growth rate of the wave increases with increasing drift velocities of the electrons. Negatively charged oxygen ions (O -) decrease the growth rate; however, the growth rate is very sensitively dependent on Oion density, especially when its density is greater than that of the positively charged oxygen ions (O + ). Interestingly, the dispersion characteristics of KAWs can be made insensitive to the presence of the heavier ions by an appropriate choice of their densities and temperatures.

We have studied the combined effect of the pressure anisotropies of lighter and heavier ions of opposite polarities on solitary waves in a plasma composed of these ions as well as kappa described electrons of solar and cometary origin. Using the theory of Chew, Goldberger, and Low (the CGL theory), the anisotropies of all three ions have been included in the derivation of the Zakharov–Kuznetsov equation. The effects of various combinations of pressure anisotropies of both lighter as well as heavier ions of opposite polarities have been considered. From the figures, plotted for parameters observed at comet Halley, it is seen that different properties of the solitary wave such as width and amplitude, as well as dispersion and nonlinear coefficients, are profoundly affected by the anisotropies of the ions. Also, the pressure anisotropy of the lighter ions determines the polarity of the solitary waves: the plasma supports compressive (rarefactive) solitary waves when the lighter ions are pressure isotropic (anisotropic).

We investigate the existence of ion-acoustic shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot solar electrons, and slightly colder cometary electrons. The KdVB equation has been derived for the system, and its solution plotted for different kappa values, oxygen ion densities, as well as the temperature ratios for the ions. It is found that the amplitude of the shock wave decreases with increasing kappa values. The strength of the shock profile decreases with increasing temperatures of the positively charged oxygen ions and densities of negatively charged oxygen ions.