The Louisiana Accelerator Center
The position of a scanner and
its influence on the beam spot size in a nuclear microprobe.
Alexander D. Dymnikov *, Gary A. Glass, Bibhudutta Rout
Abstract
Once focused, the ion beam in a microprobe can be scanned over the sample
by using a set of two orthogonal mag-
netic coils or electrostatic deflection plates positioned before, inside
or after the focusing system. In the paper the influ-
ence of the scanner position on the beam spot shape is considered for different
focusing systems such as triplet,
quadruplet and sextuplet and for two different emittances of the beam.
The numerous graphs show the dependence
of the shape of the spot and the density distribution of the beam on the
scanning radius.
Magnetic sextuplet as a zoom
lens for the nuclear nanoprobe at the Louisiana Accelerator Center.
A.D. Dymnikov *, G.A. Glass
Abstract
A new quadrupole focusing system-magnetic sextuplet (RMS), with the same
symmetry as the Russian quadruplet
(RQ), has been proposed and is presently under development. The RMS has
the same demagnifications and the same
focal lengths as the RQ system and it can have the same spherical aberration
in both planes. Its main feature, however,
is the capability to change the demagnification over a wide range from
1 to greater than 1000 by changing the excitation
of the middle lenses. In the RMS it is possible to obtain a point crossover
between the middle lenses with a corre-
sponding minimum sensitivity to the relative rotation of both triplets
around the longitudinal axis. By changing the
excitation of the middle lenses, the optimal demagnification for every
emittance can be found and for every beam
emittance it is possible to achieve a minimum spot size by varying the
sizes of collimator diaphragms and the distance
between them. All capabilities of the RMS are numerically investigated
and the smallest beam spot size and appropriate
optimal parameters of the system have been found for different emittances.
More content available soon.
|
