CDSM-FS - Feasibility Study of a Coupled Dark State magnetometer

An absolute scalar magnetometer offers superior stability and offset-free measurements of the magnetic field magnitude. In space, it is used for improving the absolute accuracy of vector magnetometers, which also measure the direction of the magnetic field. In several cases, full science return can only be achieved by a combination of vector and scalar magnetometers. Existing scalar magnetometers are based on complex instrument designs, which have significant mass and power consumption. A miniaturized scalar magnetometer is therefore a key technology for a number of future space missions (e.g. ESA's Europa Jupiter System Mission to Jupiter's moon Ganymede). In the frame of this project a feasibility study of a new type of scalar magnetometer called Coupled Dark State Magnetometer (CDSM) was carried out. It included the investigation of its technical readiness and scientific merit for space applications, the concept for a TRL 5 (component and/or breadboard validation in relevant environment) compliant design, a detailed investigation of key components as well as the identification of possible challenges for a reliable operation in space. The CDSM is a kind of optically pumped magnetometer. This means that the energy from a light source (e.g. laser diode) is used for exciting electrons in an atom in order to gain information about the magnitude of the surrounding magnetic field. In case of the CDSM the optical source is a specially modulated laser light, which excites Rubidium atoms stored in a glass cell. The measurement of the magnetic field is based on the Zeeman Effect in free atoms. Here, the energy shift of the atomic levels is described by the so called Breit-Rabi formula, which only contains fundamental natural constants (such as Land factors, Bohrs magneton and Plancks constant). Therefore, the determination of magnetic fields is reduced to a frequency measurement, which can be done with highest accuracy. During the feasibility study improvements have been made to a TRL 3 (characteristic proof of concept) compliant test set-up for a better resource estimation of the most relevant instrument parts. The current best estimates for mass and power are 700 g and 1.0 W, respectively. All technology and every component are available so that there is nothing that could prevent a further TRL uplift of the CDSM to level 5 and higher.