摘要
For ion-acoustic waves in a plasma with non-isothermal electrons, the MKP equation is its governing equation. The instability of a soliton solution of MKP equation to two-dimensional long-wavelength perturbations is investigated up to the third order. It indicates that the one-soliton solution of MKP equation is unstable if v = -1 wheras it is stable if v = 1 until the third order approximation has been considered.
