Authors: Simeonov, L.I.
Reference: Comp.Rend.Acad.bulg.Sci., 50, 1, 39-42 , 1997.
Abstract:
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.