Neutral-beam design options. [Design and cost optimization] Page: 1 of 11
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NEUTRAL-BEAM DESIGN OPTIONS- 2
J. W. Stearns, K. H. Berkner, and R. V. Pyle :,'' '
LAWRENCE BERKELEY LABORATORY
The designs and costs of magnetic-confinement experimental devices and
reactors can be affected strongly by the choice of parameters for the neutral-
beam injection system. To provide the designer with information with which to
estimate the physical and cost consequences of variations in energy, neutrali-
zer thickness, ion-species mixtures, etc., we are carrying out parametric
studies of the neutralization efficiency. Some of the results are reported
here. The data base is too small and uncertain to permit calculations which
would optimize all aspects of designs
The designs and costs of magnetic-con-
finement experimental devices and reactors
that use neutral injection for heating and/
or fueling can be affected strongly by the
choice of parameters used in the neutral-
injector design. For example, the develop-
ment and construction of the neutral-
injection systems for the TFTR tokamak(')
and the MO mirror experiments account
fo roughly one-half of the total hardware
costs. Thus, the consequence of a rela-
tively small design change may amount to
several million dollars.
As neutral-beam-system developers, we
are asked such questions as: "What will
happen if the length of the neutralizer is
decreased?," or, "What research and devel-
opment efforts are most important to the
injector development program?" Unfortu-
nately, there are very few reliable data on
such important topics as gas efficiencies
or atomic-ion fractions attainable in the
ion source of an injector. As a result, we
must base our calculations on plausible
values for these quantities. Much more
research should be done in these areas.
*Workdone under the auspices of the U.S. ERDA.
at this time.
The data base is much better for atomic
and molecular collision processes. The
work reported here is concerned with the
consequences of these collisions, when
different assumptions are made about neu-
tralizer thickness, atomic-and molecular-
ion-species mixtures in the plasma source,
and collision cross sections.
This paper is an extension of a previous
report which gives some of the motiva-
tion and physics in more detail. In parti-
cular, we show
1. The effects of changing the neutralizer
thickness (molecules/cm2) on the produc-
tion of 20- to 400-keV deuterium-atonm
2. The effects of changing the ion-species
current mixtures in the accelerated
beam from D+:D2:D3 = 60:20:20 to
90:7:3, with and without recovery of
the kinetic energy of charged particles
emerging from the neutralizer.
For simplicity, we concentrate mainly on
injectors in which positive atomic- and
molecular-ions are accelerated and then
partially neutralized in D2 gas; we also
show some results for D beams. As an
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Stearns, J. W.; Berkner, K. H. & Pyle, R. V. Neutral-beam design options. [Design and cost optimization], article, April 1, 1976; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc1450193/m1/1/: accessed April 22, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.