Overview and Initial Results from the Bias Test Stand

Control of the current and voltage distribution of end-biased electrodes is a long term goal at TAE Technologies. The Bias Test Stand (BTS) is a testbed built by TAE to study different electrode configurations and design features for the purposes of neutral density control (neutral pumping), arc reduction, thermal management (integrated cooling) and testing new feedthrough designs. The main goal of BTS is to rapidly iterate upon the electrode designs and operational scenarios as to maximize the bias potential during a sustained plasma discharge, with a target potential of 9 kV. The electrode configuration must provide the desired bias potential as well as source current without uncontrolled arcing. BTS operates in a magnetic mirror configuration at 1 kG in the central chamber and 10 kG at the mirror. Both ends of the mirror have seven planar concentric electrodes that can each be biased, floated, or grounded independently. Performance and characterization of BTS will be presented for operation up to 1.5 kV with 100 ms pulse durations. A formulation for calculating the probability distribution function for electrode arcing was developed and will be presented. The probability distribution function will be used as a metric for comparison between electrode designs; initial results will be presented.