利用扭秤进行空间干涉仪的地面测试技术

Testing of spatial interferometer on ground by using torsion pendulum technology

空间干涉仪作为下一代重力卫星、空间引力波探测计划的核心部件之一,其灵敏度远高于目前电容式读出的惯性传感器。但由于空间干涉仪涉及技术细节过多,需在地面研制阶段接受大量测试,而低频测试频段以及极低噪声环境的苛刻要求成为当前地面测试阶段的最大挑战之一。该文介绍以悬挂扭秤为核心技术的地面测试平台,其在竖直方向可由悬丝平衡地球所带来的引力影响,而在水平方向可模拟准自由落体状态。选用经过特殊设计而成的悬挂扭秤作为测试对象,可将地面测试中的主要噪声——地面振动噪声降低3~4个量级,使得加速度噪声在观测频段可低至10−13 m·s^−2·Hz^−1/2@mHz,已达到目前该频段的测量极限,该技术也是目前国际上公认的空间干涉仪地面研制阶段的最佳测试平台之一。

Spatial interferometer is one of the core parts in the space mission,such as gravitational satellite,space gravitational wave detector project and so on.Compared with the traditional capacitance readout inertial sensor,interferometer is famous for its outstanding resolution.Meanwhile,too many technologies are involved during the development.The interferometer needs a variety of tests on the ground.One of the greatest challenges is to reach a very quiet environment at very low frequency band.In this paper,the suspended torsion pendulum system is introduced as a ground testing bed for interferometric technologies investigation.Given the dominant effect of gravity along the vertical axis,the best approach to reach the ultra-low noise environment on ground is to choose orthogonal observation frames along horizontal axes.To this end,a torsion pendulum is the worldwide preferred experimental framework.Because of the unique structure of the pendulum system,the seismic noise,which is the major noise on the ground testing,could be decreased by three to four level.The torsion pendulum testing bed could reach sensitivities at the order of 10^−13 m·s^−2·Hz^−1/2@mHz.