Authors: Simeonov, L.I.
Reference: Comp.Rend.Acad.bulg.Sci., 43, 8, 47-50, 1990.
Abstract:
The implementation of carbon foil (CF) time-of-flight (TOF)
energy and mass analyzers in space mass spectrometry has shown an
increasing progress in the last years. This is due to the introduction
of new concepts of design, such as the time and space focusing of the
investigated particles in a retarding field, situated behind the CF, in
the so-called reflection. As a result, a very high mass resolution is
achieved along with considerable widening of the mass range, reduction
of the accelerating high voltage and the thickness of the CF itself. In
the process of design it is essential to know the exact quantitative
dependence of the energy losses and the angle deflections on the CF
target thickness, in order to evaluate the restraints, which they put on
the technical and physical parameters of the analyzers. These restraints
are associated with the maximum energetic and angle dispersion at which
an analyzer operates within the desired mass and energy resolution. In
the paper are presented graphically results from a computer simulation
of the interaction of ion fluxes of 1000 particles of the elements H,
He, Li, O, Mg and Ag with initial energy of 20 KeV with a CF target with
thickness in the range 10 ÷ 70 Å. Presented are calculations of the
transition coefficient, the mean energy of the ion fluxes after passing
of the foil, the energetic distributions after the foil target and the
mean angle of escape. The MARLOWE simulation program, which was used, is
appropriate for modeling of the interaction ion-solid body in the lower
energetic range up to 20 KeV. The energetic range and the CF thickness
were chosen for the purposes of design, laboratory test and calibration
of a linear CF TOF reflection, prepared for space research
implementation.