Miniature focal plane mass spectrometer with 1000-pixel modified-CCD detector array for direct ion measurement

A high performance, focal plane miniature mass spectrometer (MMS) of Mattauch–Herzog geometry with a CCD-based array detector for the direct and simultaneous measurements of different mass ions is described. Miniaturization (10cm×5cm×5cm,395g) was accomplished by using high-energy-product magnet material (Nd–B–Fe alloy) and a high permeability yoke material (V–Co–Fe Alloy) for the fabrication of the magnetic sector. The electrostatic sector was machined from a single piece of machinable ceramic (MACOR). All the components of the analyzer are mounted on a single plate, which facilitate their alignment and make the instrument rugged. The modified-CCD based ion detector array has 1000 elements (20μm×2mm) and was invented in our laboratory. The photosensitive part of the CCD was replaced with a metal-oxide-semiconductor (MOS) capacitor for ion detection. The ion sensing capacitor plates are connected to the CCD gates that are operated in the fill-and spill mode providing a gain in the charge domain for the signal ions and minimizing various noises during measurements. The results reported in this article are the first application of this detector array for direct ion measurement and successfully prove the new technology. The MMS with the array detector can measure masses up to 250u with a unit mass resolution and expected to possess a sensitivity of detecting ∼5ions. The above attributes make MMS suitable for space applications for isotopic and chemical analysis and also for field applications on earth.