“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//F8A 8FFHil.l1k 'JE'lii 811k¥
In this RF gun, a graded index magnetic field is used to increase the ionization
efficiency. A key component is the magnetic focusing lens at the extraction port. This
allows very efficient differential pumping between the high pressure gun chamber and
the low pressure IEC chamber. It also provides some control of the angular velocity of
entering ions.
The UIUC RF ion-injector is shown attached to an IEC chamber in Figure 1.6, and a
photograph of the focal spot achieved with injection from this single injector is shown in
Figure 1.7. Note that ion scattering off of the center dense plasma "core" causes
noticeable (but "faint") recirculating ion beams observed in the photograph of the
discharge. With additional injectors, the recirculation pattern should become quite
symmetrical about the center. These studies did include differential pumping so that
number of recirculating passes, ~, by an ion was very low, roughly 2. The injected ion
current, I, was about SO mA. Still, based on measurements of neutrons emitted using
deuterium fuel, the Q (fusion energy gain/energy in) was remarkable for such a small
device, order of 10-6 . Based on these results, an aggressive p- 11 B breakeven
experiment using this type of IEC is discussed in Section VI.
Figure 1.6. RF Gun Attached to an IEC Chamber in
the UIUC Laboratory
CLOSING REMARKS
Figure 1.7. Photo of Center Spot Formation. The
main beam observed is a direct path along the injector
angle. Other faint light channels indicate beams for
scattering of the central core region.
As seen, a wealth of information has been developed in studies of gridded IEC devices.
However, the beam-background fusion used in these devices involves important
differences in physics compared to what is needed for future beam-beam IEC reactors.
Most notable is the need to maintain an extremely low background pressure to prevent
interactions with background neutrals. Further, physical grids are subject to damage at
high power levels. As pointed out, some studies show grids can survive at modest
powers. But, for aggressive power units such as the p- 11 B plant of Section VI, they
must be replaced with virtual electrode surfaces creating a deep potential well for ion
confinement. Upscattering out of the well must be minimized while electron
12
UNCLASSIFIED//EOAt OFFIQI.«1k 11181! 8HLV