Tuning the LEDA RFQ 6.7 MeV Accelerator

This paper presents the results of tuning the 8 meter long Radio Frequency Quadrupole (RFQ) built for the Low Energy Demonstration Accelerator (LEDA). This 350-MHz RFQ is split into four 2-meter-long-RFQs. Then they are joined with resonant coupling to form an 8-meter-long RFQ. This improves both the longitudinal stability and the transverse stability of this long RFQ. The frequencies of the modes near the RFQ mode are measured. The authors show the effect on the RF fields of an error in the temperature of each one of the 2-meter-long-RFQs. Slug tuners distributed along the outer walls tune the RFQ. The program RFQTUNE is used to determine the length of the tuners. The tuners are machined to length when the final tuning is complete.