IUAC, New Delhi
The first module of the booster superconducting linear accelerator, consisting of a total of three modules, each having 8 quarter wave coaxial line bulk Nb resonators, has been commissioned at IUAC. During initial operation of the first linac module, the energy gain was found to be much lower due to various problems which are now identified and solved. After acceleration through the linac module and subsequent re-bunching using a superconducting Rebuncher, a 158 MeV silicon beam having pulse width of 400 ps was delivered to conduct nuclear physics experiments. The other two linac cryostats and the required 16 resonators to be installed in those two cryostats are in the final stage of fabrication. Work has progressed on a high current injector that would act as an alternate source of heavy ions for the superconducting linac. The first element of the high current injector is a high Tc superconducting magnet ECR source (PKDELIS) which would be followed by a room temperature radio frequency quadrupole accelerator and drift tube linac cavities. Prototypes of the RFQ working at 48.5 MHz, and that of the DTL working at 97 MHz, have been fabricated and are undergoing tests.
IUAC, New Delhi
The frequency control of the superconducting quarter wave resonator at IUAC is currently accomplished by mechanical and electronic tuners which are operated in the time scale of seconds and hundreds of milliseconds to a few tens of microseconds respectively. Due to presence of microphonics, input rf power in the range 200-300 W was required to control the resonator for a typical field of 3-5 MV/m achieved with 6 watts dissipation. Implementation of a novel idea to damp the mechanical vibration with the help of SS-balls has helped to reduce rf power below 100 W. Though resonators are working fine at this power level, we are investigating whether further reduction of rf power is possible using a piezo actuator to control the drift of frequency. The piezo tuner working in hundreds of milli seconds range with the dynamic phase control scheme will share a substantial load from the electronic tuner. As a result, the resonator's phase lock loop will remain locked for less rf power. The initial test results of the piezo tuner will be presented.