Interdigital-H linac for unstable nuclei at INS

In the prototype facility of the Exotic-arena at INS, unstable nuclei with a charge-to-mass ratio greater than 1/10 are accelerated from 170 to 1046 keV/u by an interdigital-H linac. The designed IH linac consists of four acceleration tanks and three sets of quadrupole triplets placed between tanks. Output energy is continuously variable by changing the rf power and phase of the last operating tank. A high shunt impedance is expected from an equivalent circuit analysis. The rf measurement on the low power models is now in progress. Preliminary results of the tank-4 model shows that a resonant frequency and a shunt impedance roughly agree with the design values