COPS - A NOVEL PRESSURE GAUGE USING MEMS DEVICES FOR SPACE

摘要

The determination of the pressure and density of the residual gas in evacuated vacuum systems is of essential interest for both scientific and industrial applications. This has been recognised from the early beginnings of experiments realised in vacuum environment. Many existing measurement methods for total and partial pressure are based on classical principles having each one its own specific range of utilisation - with several advantages but also some drawbacks. The use of classical pressure gauges (e.g. Bayard-Alpert, Pirani, etc.) for space missions is often limited by the current consumption, the reliability due to the use of fragile components and generally by the mass and size of the sensor or the whole instrument. The development of highly miniaturised but reliable measurement devices for space use is therefore a prerequisite for future projects. ESA's next cornerstone mission ROSETTA, a cometary mission presently being re-scheduled for an ARIANE V launch in February 2004, is aiming now at Kuiper Belt comet "Churyumov-Gerasimenko". After a short description of the aims of this cometary mission, this paper reports about the technical realisation of the pressure sensor, especially of the Ram Gauge bringing novel MEMS (Micro-Electro-Mechanical-System) technology for the first time into outer space. It is shown that solid-state cold electron field emitters have many advantages over classical thermo-ionic emitters. This paper gives a description of the technological approaches together with some intermediate test results and concludes by a short outlook to future opportunities for such MEMS devices in space and in industrial applications.