Quantitative evaluation of gas-damping effects in high-precision gravitational reference sensors based on Monte Carlo numerical simulation
Phys. Rev. Applied 26, 024011 – Published 6 August, 2026
DOI: https://doi.org/10.1103/1j5b-7bn3
Abstract
In the context of spaceborne gravitational-wave detection, residual gas-damping noise induced by thermal molecular motion represents the primary limitation on the sensitivity of a gravitational reference sensor (GRS) operating within the mHz band. This study reconstructed and unified the microscopic physical image that characterizes the various gas-damping effects in high-vacuum free-molecular flows for high-precision GRS. This facilitates the execution of a comprehensive analytical modeling of the total gas-damping effects on the test mass (TM) within the sensitive probe geometry. An improved Monte Carlo numerical simulation method was also developed by tracking molecular scattering processes on the TM and quantifying the momentum transfer from molecular fluctuations. The normal and tangential damping force noise acting on the TM was systematically validated by this method. The results demonstrate exceptional agreement with proposed theoretical models, exhibiting minimal relative deviations of 8.7% and 0.14%, respectively. Furthermore, the study revealed a crucial conclusion that the tangential gas-damping noise acting on the TM is independent of electrode gaps in all directions. This accurate model of residual gas-damping noise was subsequently applied to the TianQin mission. A full frequency band residual gas-damping noise power spectral density (PSD) in scientific mode was demonstrated. Assuming a conservative sealed-housing configuration (i.e., no effective venting to an external reservoir), it is recommended that the electrode gap along the sensitive axis be maintained at a minimum of 5 mm to ensure compliance with the TianQin residual acceleration noise requirement. This finding is determined by the excellent agreement between the PSD and theoretical model prediction within the observation band. The incorporation of potential venting features has been identified as a means of reducing proximity-enhanced damping, thereby relaxing this constraint.
