Refraction and reflection of ion acoustic solitons by space charge sheaths

It has been found that ion acoustic solitons tunnel through the space charge sheath in front of the reflector, without time delay, but they are absorbed resonantly when the spatial width of the wave is close to the characteristic gradient scale length of the sheath. The empirical scaling laws for the reflection and transmission rates have been obtained as functions of (i) the bias voltages on the reflector, (ii) the wave width, and (iii) the density gradient scale length. The theoretical model for interpreting the observed phenomena is discussed to show the existence of the electrostatic tunnel effect in the space charge sheath area. In this model, the absorption of wave energy by the sheath, which is strong in the present experiments, was not taken into account.