Study on the calibration method of the grid-based energetic neutral atom imager (GENA) for the Queqiao-2 Mission

The grid-based energetic neutral atom imager (GENA) onboard the Queqiao-2 satellite is the first lunar-based magnetospheric energetic neutral atom (ENA) panoramic remote sensing imaging payload. It aims to provide scientific data support for the study of the injection triggering mechanism of the Earth's magnetosphere substorm, the magnetotail energy conversion mechanism, and the generation process of the Earth's magnetic storm through high-temporal and spatial resolution observation data. The GENA innovatively combines the time-of-flight method with the two-dimensional coded modulation imaging technology to achieve accurate detection of single-particle events and large-scale, high-resolution magnetospheric neutral atom remote sensing imaging. It can be used to measure 4keV-200keV H atoms and 8keV-250keV O atoms, and the energy resolution is better than 1keV@10keV. At the same time, its instrument field of view is greater than 20°×45°, and the resolution of ENA remote sensing images is better than 0.5°. To accurately calibrate the above performance indicators of the GENA, a study on the calibration method of the GENA was carried out. The accelerator beam calibration test verifies the GENA's ability to identify the type of neutral atoms and measure their energy, and the optical calibration test verifies the GENA's field of view coverage and image resolution. The calibration test results show that the GENA's ability to measure H and O atoms can cover the design indicators.