Hazard function exploration of tokamak tearing mode stability boundaries

It is possible to model an event prediction problem by a hazard function (event rate) and a phase space trajectory. Compared with typical event prediction approaches, the hazard function has two significant advantages. First, it has a time localized and quantitative interpretation (events per time). Second, event rate models can be used to generate event predictions for arbitrary look-ahead horizons conditioned on future controls with respect to a dynamical systems model. To be able to apply these advantages, we are first required to develop the necessary tools to effectively learn (correct) hazard function models from data. We report scaled-up hazard function analysis applied to tokamak data for tearing mode onset characterization. A particular tearing delta-prime proxy does not significantly increase the likelihood of the hazard model. Shot-database searching and feature extraction tool-chains developed at the DIII-D National Fusion Facility are exploited. Multiple methods for understanding and visualizing the properties of the estimated hazard function(s) are applied, including partial dependence plots.