RILAC: RIKEN Heavy-ion Linac

The RILAC consists of a Cockcroft-Walton injector and six acceleration tanks of the Wideroe type. The radio frequency is required to be variable for a coupled operation with the RRC. Its range covers 17-45 MHz, while in an injector mode to the RRC the lowest frequency used is 18 MHz. The maximum effective acceleration voltage is 16 MeV. In this injector mode RILAC is able to accelerate ions have a mass-to-charge ratio smaller than 28, up to energies of 0.7 MeV/nucleon (at 18 MHz) - 4.0 MeV/nucleon (at 45 MHz).

Even with a fixed radio frequency, the output beam energy of this linac can be lowered by switching off the last one or two acceleration tanks. Accordingly, the output beam energy of the RRC can be lowered below the nominal value obtained with the fundamental acceleration harmonics of 9; the acceleration harmonics of 10 and 11 are used for this purpose. The lowest energy of 7MeV/nucleon is obtained at 18 MHz with the acceleration harmonics of 11.

The ECR ion source, named NEOMAFIOS, is operated at 8GHz and generates a mirror magnetic field by permanent magnets. It is compact and consumes less electric power than 20 kW, and is therefore suitable for use at the high voltage injector platform.

Following figure shows a photograph of the RILAC as seen from the injector side.

Specifications of the RILAC.

Injector
	Type                  Cockroft-Walton High Voltage Generator
	Max. Voltage          500 kV
	Ion Souce	      ECR (Electron Cyclotron Resonance)

Linea Accelerator
	Type		      Variable Frequency Wideroe (6 tanks)
	Frequency Range	      17-45 MHz
	Frequenct Tuning      Shorting plate and trimmers
	Total Accel. Voltage  16 MV
	Charge/Mass Ration    >= 1/28

Dimensions
	Total length	      40 m

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last updated on 25 Oct 1996 by T.Ichihara (www-admin@rikvax.riken.go.jp)