The helical structure of the chiral smectic C alpha phase (SmC alpha*) is unwound by an electric field and a field induced SmC alpha*-smectic C phase transition occurs at a certain field strength, which is similar to the chiral smectic C phase (SmC*) where the transition is interpreted as a condensation of solitons. The pitch of SmC alpha* without the field is very short and the soliton excited at the phase transition should be a discrete type, in contrast with SmC* where the pitch is large enough and a continuum theory is applied. It is shown that the SmC alpha*-SmC transition is of the second order like the SmC*-SmC transition, while the interaction between discrete solitons is quite short range and the condensation process of solitons occurs drastically. The dependence of wave number of the helical structure on the field strength is possibly something like staircase. At high field region, discrete soliton lattices of short period become unstable showing fragile property.