Measurement of Masses and Forces with the Aid of Free Magnetic Suspension

Free magnetic suspension allows to measure forces which result from various physical causes including gravity, in diverse atmospheres through the wall of a container with an external balance. The paper deals with suspension based devices for measuring forces between 10 -8 and 1 Newton, corresponding to mass changes between l ug and 100 g. The paper refers to intrinsically stable suspensions by magnetic forces and treats artificial stabilization of permanent magnets in attraction and repulsion, especially with the aid of control loops. Several kinds of position sensors and selected configurations of magnets are described. Newly developed suspension balances withstand internal pressures up to 5 kbar. Some applications of such devices are included. Suspension balances are advantageous in so far, as the balance proper is totally separated from the object in the reaction chamber without considerable loss in precision and dynamic properties.