RTOF is designed to complement DFMS by extending the accessible mass range and increasing the temporal resolution of the ROSINA measurements. TOF instruments have the inherent advantage that mass spectra are recorded in a single shot without performing time-consuming mass scans. Reflectrons, such as the one used in this instrument, help to increase the mass resolution. With the reflectron, RTOF achieves a mass resolution of m/Δm = 4600 (at 50 % peak height). The instrument includes two similar but independent source-detector systems, one for cometary ions and one for cometary neutrals. The two sources are similar from the construction point of view, but one source is optimized for the gas mode (Storage Source) and the other one is optimized for the ion mode (Ortho Source). With both using the same reflector, this configuration guarantees high reliability by almost complete redundancy. RTOF suffered from some anomalies in the high voltage electronics and was therefore operated on lower ion energies than planned. This led to a loss in sensitivity and in mass range, but it was still possible to operate RTOF whenever power and data rate was available.
Single Reflection Spectrum after 60 sec acquisition time
Triple Reflection Spectrum - Resolution R50% = 4500
Comparison between the spectrum measured by Giotto and the spectrum from RTOF
Full mass range spectrum taken from RTOF
Zoom on the Peaks @ mass=16 and 28 amu. As one can see the sensor is able to differ between 16O and 12C1H4 respectively between 12C16O, 14N2 and 12C21H4