A ballistic laser gravimeter for a symmetrical measurement method with the inductive-dynamic catapult and auto-seismic vibration preventing

Abstract

A ballistic laser gravimeter (BLG) with a symmetrical measurement method of the gravity acceleration (GA) is considered. Special treatment is given to the problem of eliminating the measurement error due throw of the catapult when it speeds up the test body (TB). It is possible to decrease the indicated errors thanks to the use of the induction and dynamic catapult. However, a short-term boost catapult generates vibrations of the basement (i.e. a pillar) and the mechanical elements of the gravimeter, what causes auto-seismic (i.e. recoil-related) component of the measurement error. To reduce them it is proposed to launch the TB with the help of a massive platform, installed on a light spring. It is shown, that the considered BLG can provide auto-seismic component of the measurement error of less than 1 μGal. With the reduction of the light spring constant the auto-seismic component of GA measurement uncertainty is reduced. The value of this measurement error can be reduced by the use of damping in the system of BG protection from auto-seismic fluctuations. A concept of BLG with induction-dynamic catapult for symmetric method of gravitational acceleration measuring is presented. The concept is based on using electromagnetic compensator of stiffness.