A New Baking System for the HSX Stellarator

The HSX stellarator is an optimized, 4-field period stellarator designed to investigate the confinement properties of a quasi-helical symmetric field structure. As part of an upgrade of HSX, a 100 °C vacuum bakeout system was designed, installed, and commissioned. Heating is performed by 88 contact heating strips which are proportional-integral-derivative (PID) controlled using a programmable logic controller (PLC). Ceramic-based insulation blankets were installed over the heating strips to even out vessel temperatures and to reduce heat losses. First results during baking up to 50 °C show strong outgassing of water from the walls with an increase of the base pressure by more than two orders of magnitude. After baking, a clear reduction in device base pressure is observed, demonstrating the success of this wall conditioning effort and allowing for stable plasma operation in HSX. First density measurements from the 2023 experimental campaign will be presented and compared with pre-upgrade data.