New Operating Mode for the Quadrupole Mass Spectrometer

We provide an end-to-end model and implementation of a new operating mode for the quadrupole mass spectrometer (QMS). This mode has direct applications for future planetary science and cometary missions. Numerical simulations of ion trajectories in QMS systems show that through amplitude modulation of the QMS RF waveform, improved performance can take existing heritage sensors and obtain increased mass resolution, enabling novel measurements over a significantly larger mass range. A SIMION model of a quadrupole system was created which incorporated this modulation technique. SIMION simulations confirmed the accuracy of the numerical model and led to the incorporation of fringing field effects including rod bias into the numerical code. In addition, an FPGA based power control system has been developed which provides flexibility in the selection of an operating point and reduces the overall complexity of the QMS circuitry. The control system can interface with existing quadrupole mass spectrometers with both circular and hyperbolic rod cross sections and supports both single and double sideband amplitude modulation of the RF waveform.