“BEAMS”43 pages
- p. 5 …Sketch of Two Opposite Limits of the Beam·Maxwellian Equilibrium .. 38
Figure 4.5. The Definition…
- p. 6 …Comparison of Analytical and Numerical Estimates of Q-Values in a
Beam-Dominated Solution -- for a…
- p. 8 …shows the "Star
Mode" discharge where ion beams are created that pass through the grid openings…
- p. 9 …discussed later where the recirculating ions possess
beam-like trajectories passing through the center of the…
- p. 10 UNCLASSIFIED/ ;raA 8FFIIItliL ~81!! SHL'f
beam-like ions. Since electron energy loss processes such as…
- p. 11 …In addition, its beam-like reactions (highly non-Maxwellian)
make the IEC very well suited for…
- p. 13 …a beam created at the anode and accelerated by the applied cathode
voltage; a low-energy…
- p. 14 …Good convergence is required to achieve
optimal beam-beam reactivity scaling for the application that require…
- p. 15 …The observed
loss of convergence with decreasing pressure and increasing current makes achieving
significant beam-beam…
- p. 16 …For a power reactor the objective is to obtain ion
beam-beam collisions in this central…
- p. 17 …the "conventional" beam-like
one. A key issue for this concept is how much plasma compression…
- p. 19 …The
main beam observed is a direct path along the injector
angle. Other faint light channels…
- p. 21 …Note that six ion "guns" were used to create a low energy ion beam that entered…
- p. 22 UNCLASSIFIED/;SflHl 8FFIIItliL ~81!! 8HL'I'
was obtained from recirculation beam-beam reactions in a potential…
- p. 23 …The key physics point is
that the beam-beam fusion rate scales as the ion current…
- p. 26 …Scoping calculations of beam-background fusion rates predict that a 3 He- 3 He reaction
product…
- p. 27 …of the ion density squared
scaling for beam-beam reactions.
REFERENCES
2.1 R. L. Hirsch…
- p. 28 …As such, the beam convergence (compression) is
limited to lower values, hence lower core densities (an…
- p. 30 …by
the intersection of the multiple ion beams, serves to deflect ions into the escaping jet…
- p. 31 …The result is the
formation of the intense space charge neutralized ion beam (or "plasma jet…
- p. 32 …in the
symmetric microchannels into a directed beam or jet.
Comparison to a Conventional "Plasma" Thruster…
- p. 33 …The ion beams finally exit through an opening in the ground sphere of the IEC device…
- p. 35 …These devices operate with ~ 80- keV D-ion beams using the non-Maxwellian
character of the…
- p. 36 …Two ion sources inject
40-keV deuterium and helium-3 ion beams toward the center of…
- p. 37 …Indeed in this case fusion is dominated by beam-beam (non-
Maxwellian reactions). Also, the dipole…
- p. 38 …the center potential and consequently allow incoming
beam ions to penetrate into the core region. In…
- p. 39 …Comparison of Analytical and Numerical Estimates of Q-values in
a beam-Dominated Solution -- for a…
- p. 40 …Hora, "Converging Beam Neutron Source for
Driving a Sub-critical Fission Reactor", Proceedings, ICONE 8, CD…
- p. 41 …Namely, the time scale for
collisional degradation of the beam-like ion distribution function is crucial…
- p. 42 …For example, a tightly focused monoenergetic ion beam is in
fact a pessimistic scenario, because different…
- p. 44 …Thus, weak sinks and strong sources will result in a
large beam population, increasing the beam…
- p. 45 …Sketch of Two Opposite Limits of the Beam-Maxwellian Equilibrium. The solid line
corresponds to a…
- p. 46 …injected beam current, average injection energy, energy spread associated
with the velocity component in both parallel…
- p. 47 …As stated in Section I, the current scaling
for beam-beam reactions is strictly 12. However…
- p. 48 …is very encouraging for formation of deep wells
in IEC devices designed for reactors using beam…
- p. 49 …To do this, it is
assumed that the electrostatic confinement equilibrium ion beams are proportional to…
- p. 50 …When an ion beam is hot, the waves excited by the instability are ion acoustic
type…
- p. 51 …Rider was particularly interested in the claim that due to its beam-like non-
Maxwellian plasma…
- p. 52 …Diagram Showing Equipotential
Surfaces of the IEC Cathode Grid and Their
Focusing Effect on a Beam…
- p. 59 …of detectors, the detector configuration, the collimated
beam size, the acquisition time, and other scan-related…
- p. 63 …Alternately, for space
propulsion, the proton beam, augmented by injection of heavy atoms to increase the…
- p. 68 …Due to its inherent non-Maxwellian (beam-like)
plasma, the IEC is especially well suited for…
- p. 70 …This configuration is highly
non-Maxwellian due to the beam
dominated nature of the trapped ions…
UNCLASSIFIED/ ff81il 8PPll!ltllt t!l91!! SHL'I'
events take place. Accordingly, he predicted that the Q-value (defined the ratio of
fusion power out to ion input power) of an IEC device operating with a 50/50 percent
deuterium-tritium (D-T) mixture would be ~0.21 for a 50-kV square well. This
conclusion would rule out the possibility of a fusion reactor, but would leave open the
development of driven neutron sources. However, this analysis contains several
questionable assumptions. For example, a tightly focused monoenergetic ion beam is in
fact a pessimistic scenario, because different co-moving ion species (such as D and T
with the same energy) result in a finite speed difference, thus fostering ion-ion
collisions and the degradation of the ion distribution function. It would be more realistic
to consider that, in a square well, friction between species would homogenize the speed
within the ion beam a~er some time, making the speed difference infinitesimal. This
line of argument was pursued earlier by Barnes et al., (Reference 4.3) who found Q ~
1. 3 for the same system.
ION INJECTION PORT
Ion extraction grid
Ion divertor
Pseudo-spherical
well for ion confinement
a
Electron divertor
I
E=Emax
E=Eo
Anode wall (ground)
Figure 4.2. Detail of the Anode and the Ion Injection Port in PFX-I (not to scale). Ion
and electron divertors are indicated, as well as the Eo and Ern" equipotential lines that define the
ion confinement region. The Eo contour line determines the region of absolute ion confinement.
In Chacon's work, a bounce-averaged Fokker-Planck (BAFP) model was employed to
obtain steady-state solutions for the ion distribution function and to calculate associated
fusion energy gains (Q-values) in a variety of operating conditions. These is done in
terms of source and sink strengths, ion injection energies, well depths, and electrostatic
potential shapes. Thus, the limiting assumptions by Nevins- namely that ions are
confined in a square potential well, and that their distribution is tightly focused and
monoenergetic, are relaxed. When these restrictive assumptions are removed, it is
found that large energy gains (Qs of hundreds) for beam-like solutions in square wells
35
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