Strategy of detailed history method is summarized, depending on which code ITR(ions transport and reaction) was developed. Both basic method and impulse approximation method to select flight path of ions are complemented respectively. Numerical results agree with CORTEO and TRIM very well. Relation between two methods is discussed. We found reason of CORTEO results differ from TRIM's by limiting maximum of flight length derived by impluse approximation method. ITR has advantages of TRIM and CORTEO. Impluse approximation method reduces nuclear collisions simulated. Index technique is used to calculate scattering angle, which significantly improves efficiency of ITR.

Principles of ion interaction with target atoms including nucleus and electrons are introduced. We study "detail history" Monte Carlo method. An ion Monte Carlo simulation code ITR (ions transport and reaction) was developed. It shows that our code perform good results compared with TRIM and Corteo. It is faster than TRIM.

For NDP,we produce an iteration method derived from probability iteration.It is compared with linear regularization(LR) method for unfolding of NDP.Both produce good results without counts random errors.Iteration method's result is none-negative.LR method is better at the position where source distributions change steeply.Iteration method produce better results as we consider count random errors.It shows that amplifying matrix elements exponentially brings acceleration.

A simple method to calculate electrostatic fields of ion optical system and trajectories of ions in the field is discussed.The optimization methods to save disk space and accelerate the calculation process are given under condition of maintaining the calculation precision.A feasible method for searching the over-relaxation factor is present.The calculation method is applied to the calculation of a design of gridless high-resolution reflectron time-of-flight mass spectrometer.The results of the distribution of electrostatic fields,the ion trajectories and the best conditions of the fields are present.The system is adjusted to its fairly good working condition based upon these results,and mass spectra with much higher resolution are observed.