Authors: Simeonov, L.I.
Reference: Comp.Rend.Acad.bulg.Sci., 50, 1, 39-42 , 1997.
The design of time-of-flight (TOF) instrumentation for measurement of the mass and isotopic composition of ion fluxes, in space research or in the laboratory, in the last years is governed by an expanding application of units with retarding and reflector electrostatic fields. The electrostatic reflector, as a part of the TOF compartment of the mass analyzer, make its possible to compensate differences in the time-of-flight of ions of one and a same mass, which have initial energies in one and a same ion package. In such a way, the achieved time-space focusing of the ion packages considerably increases the mass resolution of the device. The present paper contains an analysis of the time characteristics of the basic linear TOF reflector. Considerations for the process of design, construction and building up of the reflector part of TOF mass analyzers are also formulated. The analysis is made initially on the base of the simplest two-stage reflector. The constructive reflector parameters, i.e. dimensions and applied voltages, are varied in a stepwise manner in order to achieve an optimum mass resolution. The optimization procedure stops when the following parameter alteration does not improve the resolution further. It was found that the two-stage reflector with optimum resolution must have a drift stage, i.e. a stage without acceleration twice as long as the reflector stage.