A novel approach to generating time of flight mass spectra for low energy neutral atom detection

Low energy neutral atom detectors traditionally use a surface to convert the neutrals into negative ions. The negative ions are then accelerated with an acceleration potential of at least 15 keV to allow them to penetrate a thin carbon foil used to create the start signal for a time of flight (TOF) spectrometer. The 15 keV accelerating potential prevents energy straggling and trajectory scattering in the carbon foil. Power supplies for the high voltage potentials are mass and power drivers for any such instruments. An additional design consideration is the suppression of secondary electrons generated at the conversion surface by the neutral atoms and incident UV photons. If the secondary electrons from the conversion process can be separated from the photo electrons, it would be possible to use them as a start signal, eliminating the carbon foil and acceleration potential. We have investigated using secondary electrons generated by the conversion process as the start signal for the TOF measurement, eliminating the need for the acceleration potential. We will present results from a proof of concept configuration, preliminary instrument design with simulations.