Ground testing of release impulse for the aluminum cubic test mass with a compound pendulum for the TianQin project

In the space-borne gravitational wave detection TianQin project, the locking and releasing of test mass is one of the key technologies. The test mass will be locked during the spacecraft launch and then released to free fall for the science phase. The residual release impulse is required to be on the order of magnitude of 10−5 kg m/s, which allows us to capture the test mass by the force authority of the capacity control. In this paper, the release impulse of the aluminum test mass is measured with a compound pendulum for the TianQin project. The test mass is locked by two tips from opposite positions, and the release impulse is obtained from the oscillation of the pendulum. When the aluminum test mass is locked and released by the stainless steel and aluminum tips, the release impulses and their uncertainties are on the order of magnitude of 10−5and 10−7 kg m/s, respectively. This provides a feasible measurement scheme for the impulse testing in the TianQin project.