Microtechnology for Experimental Space Plasma Physics

The Micro- and Nanosystems group at MC2, Chalmers and the Swedish Institute of Space Physics (IRF) in Kiruna are currently involved in a joint project to develop extremely fast shutters to be used for particle measurements in space.

Mass spectrometers have been flying on satellites from the beginning of the space era to study the Earth's and the other solar system object's interaction with the solar wind. Since the plasma in the interaction region is a mixture of particles of the solar wind (mostly protons) and planetary origin (O+, CO2+, He+, O2+ etc), mass resolving instrumentation is required to fully understand the interaction.

The time-of-flight (TOF) technique is used in many instruments to measure the time between a START event, for example when electrons emitted as the particle penetrates a thin foil or grazes a surface are collected to produce a START signal, and a STOP event when the particle impacts a detector.

Today, mass and energy analyzers used in experimental space plasma physics that are based on conventional TOF techniques are limited by the fact that the particle to be measured loses part of its velocity in the generation of the start signal. This is particularly serious for measuring low energy neutrals, where pre-acceleration of the particles is not possible. Shutter based velocity analysis can be used in particle measurements on space missions to lower the energy threshold for neutral particle measurements and improve resolution. A beneficial side effect is that it would reduce the noise generated by solar UV photons that penetrate the thin foil in today’s systems.

The shutters are based on microelectromechanical system (MEMS) technology. Each MEMS shutter consists of an array of vibrating microstructures. The resonant system should be capable of generating open times of less than 100 ns, and comply with the high demands on mechanical integrity, temperature tolerance, radiation tolerance, and power consumption associated with satellite based operation.

The project work consists of some manufacturing in the Nanofabrication Laboratory, at MC2, Chalmers, and evaluation of a first generation of prototype shutters for experimental space physics. Suitable backgrounds are applied physics or mechanical/electrical engineering