Development of a Polarimeter System for Solar Synoptic High-Sensitivity Observations

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Solar coronal mass ejections (CMEs) are a key component in generation of space weather and solar storms that can impact our society. They can damage satellites, disrupt radio communications, and even create blackouts of the electricity power grids. This project will develop an instrument to provide high-sensitivity and high-fidelity information about CMEs. The developed system will serve as a long-term platform for training students from diverse backgrounds at the Big Bear Solar Observatory.A new polarimetry system will be developed to observe the near infrared (NIR). This system has unique features including: (1) High-speed solar polarization in the NIR. Polarization measurements in the NIR can provide better sensitivity than the visible. Due to the atmospheric turbulence disturbance and the fact that several images are required for the polarization measurements, a low-speed polarimeter cannot reliably measure the true polarization. This system will be the first polarimeter that can achieve a polarization measurement speed up to 100 Hz at the NIR He I 10830 Angstrom line, and thus provide a true polarization measurement with high sensitivity for solar CME investigations; (2) the polarimetry system will be the first instrument that acquires polarization measurements in the NIR He I line for CME associated events on a regular and synoptic basis over an instant 2-dimensional field of view (FOV) up to 320’’ x 256’’ without the need of the long slit scanning currently used in the tradition spectrograph, which is mandatory to search, monitor, and track CME events; (3) The high-speed 2-dimensional polarization images will be used to derive the diffraction-limited images for each of the Stokes vector components using the blind deconvolution technique, and thus to provide diffraction-limited magnetic field images that current large ground-based telescopes would not offer, and thus provide good image quality over a large FOV that is close to that provided by a space-based instrument.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.