Progress of two RF driver based negative ion source experiment

Abstract

Multi driver based RF ion sources have emerged as the most promising option for producing the plasma in large ion sources required for fusion applications. In India, under domestic long term fusion program, a negative ion source development program has been initiated and a 100kW inductively coupled - single RF driver based negative ion source (ROBIN) has been installed and operational at Institute for Plasma Research (IPR). To move forward from single driver source operation to multi-driver source; apart from source size there are many configurational differences and issues exist, which need to be studied. In this regard, an 180kW inductively coupled two RF driver based negative ion source experiment is designed. The experimental plan is divided into two phases: Plasma operation phase and Beam extraction and acceleration phase. Each phase is further divided into two operational modes: Air mode (outer boundary of the source including matching circuit is outside vacuum and exposed to air) and Vacuum mode (source chamber including matching circuit is inside vacuum) with grounding (source is in ground potential) and floating (source is in higher potential) configurations of the RF generator. A vacuum chamber has been specially designed to accommodate all these phases of operations. The data acquisition and control system (DACS) of the experimental system is designed based on CODAC guidelines. Probe and spectroscopy diagnostics constitutes the principal diagnostics. Procurement of hardware involved in first phase of the experiment has been initiated with a mechanical design assessment of various components of the ion source. The experiment is housed near the India Test Facility (INTF) inside ITER-India laboratory. The paper discusses the experimental system with emphasis on the aspects of mechanical, electrical and DACS integration.