The kinetics of defect accumulation under irradiation: Many-particle effects

The kinetics of Frenkel defect accumulation under permanent particle source (irradiation) is discussed with special emphasis on many-particle effects. Defect accumulation is restricted by their diffusion and annihilation, A + B → 0, if the relative distance is less than the critical distance r0. A novel formalism of many-point particle densities based on Kirkwood’s superposition approximation is developed to take into account aggregation of similar defects (A-A, B-B). The dependence of the saturation concentration after a prolonged irradiation upon spatial dimension (d = 1, 2, 3), defect mobility and the initial correlation within geminate pairs is analyzed. It is shown that the defect concentration really saturates only for d = 3 whereas for low dimensions (d = 1, 2) it is not the case because of the macroscopic defect separation into alternating domains containing defects A or B only.