Stray magnetic fields of an electromechanical catapult of an electromagnetic and induction-dynamic type of a ballistic laser gravimeter

Abstract

The article is devoted to the study of stray magnetic fields created by the electromechanical catapults of electromagnetic and induction-dynamic types. In a ballistic laser gravimeter (BLG) with a catapult of electromagnetic type, electromechanical energy is converted indirectly. The BLG with an induction-dynamic type provides a direct conversion of electromechanical energy and makes it easy to adjust the height of throwing up the test body. When an inductor is driven by a capacitive energy storage device, electromagnetic attractive forces act on ferromagnetic armature of catapult of an electromagnetic type, and electrodynamic repulsive forces act on a conductive armature of catapult of an induction-dynamic type. With the help of a mathematical model, the character of the distribution of stray magnetic fields in the catapults under consideration is established. In the electromagnetic catapult, the greatest magnetic field induction values are observed in a ferromagnetic anchor, with significant stray magnetic fields observed in the upper part of the catapult, where the radiation vacuum chamber is located. To reduce the specified magnetic fields, it is recommended to install a massive ferromagnetic shield over the electromagnetic catapult. In the catapult of an induction-dynamic type, the character of the magnetic fields is largely determined by a ferromagnetic shield covering the inductor. When producing this shield with low electrical conductivity, for example from a magnetic dielectric, the stray magnetic field decreases many times from above and from below of the inductor, which allows the catapult to be positioned near the working chamber of the BLG.