Design criteria and current status of LHCD system on SST1 machine

The lower hybrid current drive (LHCD) system for superconducting steady state tokamak-1 (SST-1) machine is in advanced stage of integration and commissioning. The system is designed to launch 1 MW of RF power at a frequency of 3.7 GHz to sustain 220 kA of plasma current non-inductively for 1000 s. The system employs a conventional grill antenna (having 2 × 32 waveguides), vacuum and air transmission lines and high power source system. A new design for vacuum transmission line, which enables better vacuum and RF compatibility has been successfully executed and tested. The transition from the narrow waveguide to WR284 waveguide system is achieved through a simple design, having stacks of copper plates with the waveguides milled in them, referred as transforming module and is successfully tested for mechanical, vacuum and RF performance. Many of the critical components have been successfully fabricated and tested as per the designs. The components and sub-systems are made ready and the integration is in progress. All the components are actively cooled and are compatible with 1000 s operation.The performance tests and current status of various sub assemblies and partially integrated LHCD system is discussed in detail in this paper.