Research on High-Precision Resonant Capacitance Bridge Based on Multiple Transformers.

Area of Science:

• Astrophysics and Cosmology
• Gravitational Wave Astronomy
• Instrumentation and Measurement

Background:

• The Taiji program aims to detect mid-to-low frequency gravitational waves (0.1 mHz to 1 Hz).
• Achieving the required acceleration residual sensitivity (3 × 10^-15 ms^-2/Hz^1/2) necessitates a capacitance sensing resolution of 1 aF/Hz^1/2.
• Existing resonant capacitance bridges face challenges in noise reduction and parameter optimization.

Purpose of the Study:

• To introduce a novel approach for reducing thermal noise in resonant capacitance bridges.
• To enhance the capacitance sensing resolution for gravitational wave detection systems.
• To mitigate performance demands on other parameters within the bridge system.

Main Methods:

• Developed a novel scheme to reduce bridge thermal noise without optimizing existing transformer parameters.
• Utilized simulation to predict noise reduction and parameter impact.
• Conducted experimental validation of the proposed noise reduction scheme.

Main Results:

• Simulations showed a noise reduction to 0.7 times the original level.
• The scheme demonstrated further noise reduction when combined with other parameter optimizations.
• Experimental results confirmed a 0.7 times noise reduction and improved capacitance sensing resolution to 0.6 aF/Hz^1/2.

Conclusions:

• The proposed method effectively reduces thermal noise in resonant capacitance bridges.
• The enhanced capacitance sensing resolution supports the Taiji program's gravitational wave detection goals.
• The approach relaxes constraints on other bridge performance parameters and improves robustness to frequency variations.