AAWSAP DIRD, Inertial Electrostatic Confinement Fusion, March 2010

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beam-like ions. Since electron energy loss processes such as radiation emission are
serious, the Lawson temperature criterion must be modified for the IEC. A first rough
estimate is the Te/T1< 1/3 for DT. (Here T1 and Te are the ion and electron
"temperatures", respectively). Control of this ratio is a complex physics issue, involving
the relative ion and electron source rates and energies and the potential well structure.
In later sections use of p- 11B (hydrogen-boron-11) fuel in the IEC is considered. This is
very attractive since it provides all charged particle reaction products, making this an
unique "aneutronic" system. Such a reactor represents a truly ideal system from an
environmental and energy sustainability perspective. However, for such fuels, t he
Larson criterion becomes much more demanding, increasing nT by two orders of
magnitude and T to 150 kV. Also, for the IEC, a Te/T1< 1/9 becomes essential. (Using
temperature ration is a very simplified representation. The radiation losses are quite
sensitive to deviation in the actual energy distribution of the ions and electrons. For
example, electron Bremsstrahlung emission primarily comes from the high energy "tail"
of the electron distribution while energy transfer with ions is dominated by the "foot" of
the electron distribution. At high powers, interactions in these regions can become quite
non-linear, depleting or "burning out 0 the local populations in these regions. This effect
causes energy losses to saturate, hence can be quite beneficial under some
circumstance. However, the phenomenon is complex to evaluate numerically, so little
has been reported on it for IECs to date). The very aggressive p- 11B Lawson
requirement is employed in the design of the breakeven experiment of Section VI.
While this discussion of IEC physics has been greatly simplified, it hopefully provides
more insight into the basic concepts and issue before delving into more detail.
IEC BACKGROUND
Inertial Electrostatic Confinement (IEC) was conceived of by Philo Farnsworth, the
inventor of electronic television, as an approach to fusion power using electrostatic
fields for confinement (Reference 1.2). When he did this in 1955, the prime approaches
being pursued worldwide were magnetic confinement or inertial (laser compression of
targets) confinement. In fact, electrostatic confinement had been written off by most
scientists due to Earnshaw's theorem (Reference 1.4) which stated that plasma could
not be confined by electrostatic fields alone. That was simply an expression of the fact
that use of a biased plate to confine one species, say ions, would automatically attract
the opposite species, electrons, such that the whole plasma would transport to the
plate. Farnsworth seemed to intuitively understand that this theorem assumed steady­
state, so that if, as in IEC, the ions were dynamically moving and confined, they would
electrostatically confine the electrons. Farnsworth went further and realized that in a
spherical system virtual electrodes would form a high density plasma region if the
confined ions were focused at the center of the sphere (Reference 1.2).
While Hirsh worked with Farnsworth to demonstrate early experimental success with
IEC experiments (Reference 1.2), the concept passed from view as magnetic and
inertial confinement resea1rch exponentiated. Then in the late 1990s R. W. Bussard
revived the concept with the hybrid IEC magnetic approach (Reference 1.6-1.7). In this
approach the electrons were confined in the magnetic field, forming a potentials trap for
ions. [Note the similarity to the original conceptual potential well discussed by Elmore,
et al. (Reference 1.1)]. Upon invitation by R.W. Bussard to join this effort, the author,
George Miley, undertook supporting experiments that were a variation of the original
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