This phase I SBIR project will develop a micromachined charged particle energy collimator plate to be used as a principle component in a micromachined plasma spectrometer. The construction of a micromachined device will enable plasma spectrometers to be easily accommodated into NASA?s strategy for using many small nanosatellite spacecraft to perform scientific measurements. A novel high aspect ratio etch process for silicon will be combined with other semiconductor processes to produce a device 1 cm ' 1 cm in area capable of collimating charged particles with energies up to 100 keV. The advantages of the silicon micromachining approach are that very high aspect ratio (>50:1) channels can be built which will significantly lower the voltage required for energy selection. The use of semiconductor processing techniques also addresses the issues of high volume manufacturing, reliability and quality control. The phase I project will demonstrate the basic fabrication process for the collimator plate. Phase II will be used to refine the design and mate the particle collimator plates with the energy discriminator under development at NASA Goddard and the Applied Physics Lab at Johns Hopkins and a backend microchannel plate stack to build a complete spectrometer unit.