Construction of the New Amplifiers for the RIKEN-LINAC

New tetrode based amplifiers have been constructed for the RIKEN heavy-ion linac, so called RILAC, replacing 36-year-old amplifiers to improve their reliability as a main injector for the RIBF accelerator complex. The RILAC is a DC machine and their frequency are tunable between 18 to 40 MHz so as to be capable of accelerating heavy ions with mass-to-charge (m/q) ratios up to 28. The new rf amplifier is based on a tetrode THALES/SIEMENS RS2042SK coupled with a tetrode THALES/SIEMENS RS2012CJ with a grounded grid circuit. The maximum output power is 150kW with a frequency ranging from 18 to 40 MHz. The amplifierwasoriginallydesignedforRIKENRingCyclotron. Since we have many experiences with this type of amplifier, some modification to avoid exciting the parasitic modes which might damage the cavity and/or the amplifier itself. Their construction started in April 2013 and installation was performed in January 2014. After the installation their commissioning has been successfully made. Beam services started in March 2014, and the new amplifiers were operated without any troubles.