“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…
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The corresponding ion density profile, shown in Figure 4.8, has a high value inside the
virtual cathode (center core plasma) and also a peak in front of the grid (real cathode).
----,-----------
"-g
-I ,l
u
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"- >,
~
~ icc
- •------'--
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Radios [ml Radius [m]
Figure 4.7. The Double Well Potential Calculated With Figure 4.8. Ion Density Profile for Potential
IXL Code for di3perp, i=I4keV, l;=SSA, Ie=S9A Well Shown in Figure 4.7
An important new insight obtained in
the study revealed that these potential
profiles create ion density distribution
functions completely different from the
ones observed when a single well
electrostatic potential exists. Two ion
density peaks were commonly observed
- one in the central IEC core region, and
one near the cathode wire grid as seen
in Figure 4.8. In this manner, the single
ion peak created by the single well
potential is split into two peaks. The
central ion peak has a much smaller
radius than the original peak. This
causes higher ion densities to occur in
the central potential well, which is
essential for the achievement of high
vw, Error
80 9.5163e-08
-- - 1.5155~9
9.1482
70 0.99906
., --+--·
JO .. I ------- OD ""'" {ftoecl I
JO ., ., 70
CalhodecWTCm [A]
Figure 4.9. The D-D Fusion Reac:::tion Rate Versus
Cathode Current for dEperp,1 = 8 keV
fusion rates. However, since the fusion core radius in these calculations is very small
on the order of 0.4 cm - 0.9 cm, the total number of neutrons emitted per second is too
low to create useful fusion power (see Figure 4.9). Still, the physics principles
illustrated provide important insight into injection issues.
A reduced angular momentum spread and higher injection energies would be required
to correct the well volume problem. Still, the D-D fusion rate scaling of 15 is
encouraging, and it is indeed surprising that this large angular momentum spread
achieves such distinct double well structures. As stated in Section I, the current scaling
for beam-beam reactions is strictly 12. However, as shown by Tzonev et al., nonlinear
changes in the potential well shape and ion density profile combine to cause the higher
power current scaling law. It would be anticipated, however, that this effect would
saturate at some current, tending back to the fundamental 12 relation. Along these
lines, it should be noted that prior investigators also predicted scaling laws with
40
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