Interpretation of Experiments on Ion Acoustic Soliton

Effects of a higher order nonlinearity and of an ion temperature on a profile of ion accoustic soliton are discussed by obtaining a stationary solution of a Vlasov-Poisson system with Boltzmann distribution for electrons. It is shown that recent experimental results are not properly explained by the Korteweg-de Vries equation where only the lowest order nonlinearity and a small excess mach number are assumed. The contributions of a higher order nonlinearity and of a finite ion temperature modify the soliton wave-form in a quantitative agreement with experimental results.