OBLIQUELY PROPAGATING ION-ACOUSTIC SOLITONS IN A MULTICOMPONENT MAGNETIZED PLASMA WITH NEGATIVE-IONS

Oblique propagation of ion-acoustic solitons in a magnetized low-P pla sma consisting of warm positive and negative ion species along with ho t electrons is studied. Using the reductive perturbation method, a KdV equation is derived for the system, which admits an obliquely propaga ting soliton solution. It is found that if the ions have finite temper atures then there exist two types of modes, namely slow and fast ion-a coustic modes. The parameter determining the nature of soliton (i.e. w hether the system will support compressive or rarefactive solitons) is different for slow and fast modes. For the slow mode the parameter is the relative temperature of the two ion species, whereas for the fast mode it is the relative concentration of the two ion species. For the fast mode it is found that there is a critical value of the negative- ion concentration below which only compressive solitons exist and abov e which rarefactive solitons exist. To discuss the soliton solution at the critical concentration, a modified KdV equation is derived. It is found that at the critical concentration of negative ions compressive and rarefactive solitons co-exist. The effects of temperature of diff erent ion species, angle of obliqueness and magnetization on the chara cteristics of the solitons are discussed in detail.