Abstract: By combining linear processing and topological mapping with numerical method,the non-linear differential equations for the defect Concentration and temperature in the case of locating the isotropy crystal wafer in irradiation by ion-beam have been solved. The paper has proved that when the defect production velocity and the temperature of the thermostat, the controllable parameters,are in some range, there are the defect concentration and temperature oscillate periodically with time-the time dissipative structure, studied the dependence of crystal properties on the frequency of self-excited oscillation and irradiation conditions. Take the silicon wafer as an example,the paper presented the frequency domain and the several specific frequencies and amplitudes of self-excited oscillation.

Key words: irradiation, defect concentration, silicon wafer, self-excited oscillation