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Project Progress

This project seeks to miniaturize and shock-harden an electrospray ionization rotating field mass spectrometer (ESI-RFMS) for high precision measurements of aqueous geochemistry on Mars (Fig. 1). It has the strengths of being small, low power, low mass and requires no precision machining. A prototype RFMS instrument has been shock tested to 1200 g’s without degrading performance. It is similar to a quadrapole in physical dimensions and resolution, but without an upper mass limit and shock tolerant. An advantage over a quadrapole is the capability to simultaneously measure a range of masses imaged as rings on our detector (Fig. 2). ESI-RFMS is a soft-ionization technique, allowing for the measurement of molecules with large masses, and thus is an attractive experimental methodology for aqueous geochemical analysis enabling in situ measurements of potential chemical, isotopic, and biologic signatures.

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We have embarked on the design and use of Einzel lenses and mesh apertures in order to produce a more focused bean for mass separation within the rotating field. To further improve beam focus, we have a) purchased a larger vacuum pump, b) replaced the glass tube surrounding the detector with a grounded stainless steel tube and c) had ESF design and build a new type of RF quadrature generator. In addition, we replaced the single plate detector with a double plate assembly, with a small hole in the front plate, allowing us to visualize the beam by rastering across the small hole using direct current on the RF plates. In addition, steering the focused beam using the RF, allowed us to “image” rings of ions of different masses. Using this technique we were able to obtain spectra of Perfluorotributylamine (FC43 — a heavy organic compound used for calibrating mass spectrometers), air (N₂ and H₂O peaks) and ethyl alcohol.

Additional leveraged funding includes NASA MIDP ($100k) and DIA (~$2.5M x 4 years, annually reviewed.)