Multi-physical field disturbance noise modeling and indicator decomposition for space-based gravitational wave detectors

Taiji Program, a space-based gravitational wave detection mission, imposes an extreme requirement on the total residual acceleration noise of the test mass, demanding better than 3×10^-15 m∙s^-2∙Hz^-1/2 over the frequency range of 0.1mHz to 1Hz. Under such stringent constraints, weak disturbances originating from the spacecraft's multi-physical fields (including thermal, magnetic, electric, and self-gravitational fields) have become critical factors affecting the noise performance. This paper presents a system-level, full-link decomposition of the residual acceleration noise of the test mass. Based on the underlying generation mechanisms, the noise is systematically categorized into gas collision noise, radiation pressure noise, galactic cosmic ray impact noise, self-gravity noise, magnetic disturbance noise, electrostatic force noise, and stiffness-displacement coupling noise, thereby establishing a comprehensive set of full-link acceleration noise models. On this basis, proceeding from the top-level requirements and utilizing the proposed noise model, a quantitative analysis of each noise component is conducted, yielding the allocated noise budget for each term, along with the corresponding specification requirements for the relevant multi-physical field parameters. The full-link noise indicator decomposition framework developed in this work can provide theoretical foundations and design references for the establishment of systematic indicators for gravitational wave detection spacecraft, and the formulation of multi-physical field coupling suppression strategies.