Design and construction of four-hole ECR ion source

When a large current is accelerated, many radio frequency quadrupole (RFQ) LINAC are needed, because the acceleration limit of a RFQ LINAC is 20 mA–30 mA. Therefore the same number of ion source are needed. But the limit is not the current limit of ion source. If the RFQ LINAC has many RFQ channels, it can accelerate large currents. We designed an accelerator with four RFQ channels to prove this principle. An ion source which extracts four equal beams from one chamber is needed for this RFQ LINAC. A four-hole ECR ion source was designed and manufactured after calculating the magnetic fields by OPERA, and simulating beam trajectory using the program FUGUN. In this ion source, since four extraction holes are located off axis by about 50 mm, the beam is deflected. We calculated this deviation.