The LINAC facility at the Tata Institute of Fundamental Research, Mumbai.

The first accelerated beam from the Superconducting LINAC was successfully put on target on September 22,2002. The LINAC is being built as a booster to the 14 MV Pelletron accelerator operating at the Tata Institute of Fundamental Research (TIFR) premises. The construction of the LINAC is modular in nature, and it is planned to get an energy gain of 14 MV per charge state for heavy ions up to mass number 80, with each module giving an energy gain of about 2 MV per charge state. The booster is based on independently phased cavities comprising superconducting quarter wave resonators. Since Ohmic losses in such resonators are negligible as compared to normal conducting cavities, a substantial reduction in electrical power to sustain large accelerating fields in the cavities can be achieved. This allows compact modular operating structures for the LINAC.
 

The first accelerated beam from Phase-1 of the Superconducting LINAC Booster to the Pelletron Accelerator at TIFR was put on target by Prof. S.S. Jha, then Director, TIFR, on 22nd September 2002 at 4:00 p.m. Dr. Anil Kakodkar, Chairman, Atomic Energy Commission, who was the chief guest, also addressed the gathering. Dr. Kakodkar mentioned that development of the superconducting LINAC accelerator technology in India was an important milestone and emphasized the need to make rapid strides in developing various accelerator-related technologies in the country for research and other applications. Prof. M.B. Kurup, Dean, Natural Sciences Faculty, TIFR, presented an overview of the project and Prof R.G. Pillay, TIFR, presented the technical highlights bringing out the challenges in the LINAC construction. Prof. S.S. Kapoor, DAE-Homi Bhabha Chair, shared his thoughts on future plans in the accelerator area in the country. Shri. P. V. Bhagwat, Head, Pelletron Accelerator, BARC gave historical account of the Pelletron Accelerator Facility, from inception to the LINAC commissioning. Dr. S. Kailas, Head, Nuclear Physics Division, BARC complimented the Pelletron and LINAC teams for this achievement.

Indigenous development has been a prime consideration and the technology of lead plated OFHC (oxygen free high conductivity)copper resonators has been chosen for the superconducting cavities. The quarter wave resonators made of OFHC copper have been fabricated and electron beam welded at BARC. The brazing and annealing of the cavities in a hydrogen furnace is carried out at SAMEER and the lead plating is performed at TIFR.

To operate the accelerating cavities in the superconducting state, the cavities have to be cooled to liquid helium temperature. The lead plated cavities are mounted in liquid helium cryostats, each holding four resonators. The resonators operate at a frequency of 150 MHz and the operating electric field as well as the phase are controlled independently for each resonator. The required electronic controls for operating the accelerating modules have been developed and built at the Electronics Division, BARC.

While the cryostat modules were fabricated by Indian industry the other cryogenic subsystems were developed and fabricated in-house at TIFR. The cryostat modules need both liquid helium and liquid nitrogen and these cryogens are delivered to the cryostats via a distribution system having cryogenic valves, transfer tubes, safety valves, etc. The liquid helium is produced in a closed cycle helium refrigerator.

In phase-I of the project, twelve resonators in three accelerating modules were made ready to be mounted and operated on the LINAC beam line with all the required controls. Beam of Silicon ions in the l3+ charge state of energy of 85 MeV from the Pelletron Accelerator further accelerated to an energy of 132 MeV by these three accelerating modules. Thus a boost of about 47 MeV in energy was obtained for the injected Silicon beam from the ten resonators, which were active in the three modules during the first beam test.

The work on the Phase-II of the LINAC construction comprising of four more accelerating modules is currently in progress.