AAWSAP DIRD, Inertial Electrostatic Confinement Fusion, March 2010

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2.7
T. Takamatsu, T. Kyunai, S. Ogawa, K. Masuda, H. Toku, and K. Yoshikawa, "A
Magnetron Discharge Ion Source for an Inertial Electrostatic Confinement Fusion
Device" 7th U.S.-Japan IEC Workshop , Los Alamos National Laboratory, NM, March
14-16, (2005).
2.8
G. R. Piefer, J. F. Santarius, R. P. Ashley, G.L. Kulcinski "Progress in the
Development of a 3He Ion Source for IEC Fusion", 7th U.S.-Japan IEC Workshop, Los
Alamos National Laboratory,, NM, March 14-16, (2005).
Section III. Other Geometries
A unique feature of the IEC is the ability to vary its geometry to adapt to a number of
important near term and future applications. Here we consider cylindrical IEC
geometries, the IEC Jet extraction geometry, dipole assisted, and magnetically-coupled
IEC unit which add flexibility for use in some power applications. Other important
configurations, which are quasi-spherical, include the magnetic assisted HEPS (Polywell)
configuration, the Penning trap IEC, and the POPS oscillating IEC. These concepts are
discussed briefly elsewhere in this report so will not be included here.
CYLINDRICAL IECS
The prime alternate geometry studied for IECs is cylindrical. While originally developed
at the UIUC, the configuration has spread to other labs including the University of
Wisconsin, Kyoto University, and the Tokyo Institute of Technology. The objective is to
obtain a dense core region extending along the axis of the cylinder. This is especially
important for neutron sources since it offers a very long source that can be used for
broad area coverage of large objects such as container boxes. Other conventional
sources would require multiple "ganged" sources to do the same. A downside however,
is the high power input required for such configurations. Thus the advantage of source
length must be weighed against the alternative of moving a smaller point source over
the surface of interest.
It is not clear that the cylinder is useful for scaling to a power reactor. It can be viewed
as a 2-D version of the spherical unit. As such, the beam convergence (compression) is
limited to lower values, hence lower core denslties (an important effect for beam-beam
fusion desired for power reactors, but less so for beam-background reactions used in
most current neutron sources).
Two types of cylindrical sources (References 3.1 -3.5), shown schematically in Figure
3.1, have been studied - a gridded type which is essentially the spherical unit
converted into a cylinder, and a quite different hollow cathode design. The gridded
design was a natural variation of the original Farnsworth device and was first studied
experimentally in the 1970s by T. Dolan at the UIUC who used laser diagnostics with a
noble gas discharge to study density-temperature and species profiles. The hollow
cathode design was later proposed by G. Miley as an attempt to retain the long axial
reaction region but do away with grids.
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