Tearing mode detectability in the SPARC tokamak

To prepare for disruption prediction, the SPARC tokamak’s [Creely JPP 2020] magnetic sensor arrays’ ability to detect tearing modes is assessed. The instabilities are modeled in the ThinCurr code [Battey APS-DPP 2022] and the responses of the proposed sensors are evaluated. The tearing modes are modeled using three-dimensional current filaments running parallel to the magnetic field at the resonant surface. The inductive coupling between the current filaments, vacuum vessel, and modeled sensors is calculated. The sensor amplitudes are then assessed in the frequency domain assuming the tearing mode exhibits a sinusoidal current perturbation along the midplane. By scanning mode rotational frequency and width, the range of detectable tearing modes is determined. It is then determined if the sensitivity and placement of the magnetic sensors is sufficient for reliable detection of tearing modes.