Choose the Mathieu q value for RFQ cooler and buncher

The paper introduced the theory for cool and constraint ions in RFQ cooler and buncher, use the international comparative advanced Realistic Interaction Potential model for Monte Carlo simulation with buffer gas filled in RFQ, concluded the Mathieu parameter q value range for RFQ cooler and buncher. The conclusion is that under vacuum or air circumstances, when Mathieu parameter q is greater than 0.908, the movement of ions is unstable: under the condition of air circumstances. when Mathieu parameter is slightly less than 0.908, the ion movement has been unstable. The best Mathieu parameter q value for constraint ions is 0.3 to 0.5. (authors)