Property of Cooled Beam in RFQ Cooler and Buncher

The basic principle of the RFQ cooler and buncher, and the constrained and cooled process of the beam were introduced in this paper. By using realistic interaction potential （RIP） model to make Monte Carlo simulation, the property of the cooled beam was calculated. The beam spot and the energy dispersion of completely cooled beam keep almost constant with time, and do not vary with the buffer gas pressure and the initial ion energy. The radius of cooled beam is inversely proportional to the RF frequency of the electric field, and the energy dispersion is only related with the temperature.