Principles and technology of RFQs

The RFQ is a linear accelerator structure for low velocity ions which focuses and accelerates with the help of electrical radio-frequency (rf) quadrupole fields. It was first proposed by Kapchinskij and has since been applied in numerous labs mainly as an injector for Alvarez accelerators. The RFQ can simultaneously focus, bunch, and accelerate a high current beam from the ion source, which can be on a relatively low d.c. potential. This allows the use of special ion sources which can be bulky and can have high power consumption like sources for polarized or highly charged ions