RFQ Parameter Choice by Multi-Parameter Optimization
  Experts in different accelerator laboratories accumulated wide experience in RFQ designing. Nevertheless new tasks on high-power, high-energy CW linac designing (for example, for ADT applications) were appeared recently. Such accelerators must be practically free of beam losses. This main condition placed more stringent requirements upon beam quality at the input of each linac part. Because RFQ is used as beginning part in above accelerators beam high-quality requirements is related to RFQ primarily. It means that existing experience in RFQ designing must be enriching by new approaches and new methodology 
Boris I. Bondarev, Alexander P. Durkin