110 GHz ECH on DIII-D: system overview and initial operation

Abstract

A new high-power electron cyclotron heating (ECH) system has been introduced on DIII-D. This system is designed to operate at 110 GHz with a total output power of 2 MW. The system consists of four Varian VGT-8011 gyrotrons, (output power of 500 kW), and their associated support equipment. All components have been designed for up to a 10-s pulse duration. The 110-GHz system is intended to further progress in RF current drive experiments on DIII-D when used in conjunction with the existing 60-GHz ECH (1.6-MW) and 30-60-MHz ICH (2-MW) systems. H-mode physics, plasma stabilization experiments, and transport studies are also to be conducted at 110 GHz. The system design philosophy was based on experience gained from the existing 60-GHz ECH system. The consequences of these design decisions are addressed, as is the performance of various 110-GHz components.<>