Gridless analyzers for radiofrequency mass-spectrometers

There are well-known radio-frequency mass-spectrometers (RFMS) that are basically used for analysis of the ion and molecular composition of the upper atmosphere. The typical component of these devices is the selection cascade consisting of three plane-parallel grids fed with negative accelerating voltage. The middle grid is additionally fed with high-frequency voltage. Ions in the three-grid cascade, depending on their mass value, get more or less energy increase. This paper gives consideration to a possibility of elimination of the RFMS imperfections. Particularly, it is proposed to use the single lenses with a large focal distance, as the selection cascades, operating under the accelerating-decelerating and decelerating-accelerating modes. The calculations show that the single lenses improve not only the sensitivity, but the resolution factor of the RFMS