“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//509 QFFI~II k WE&i &•ltlf
Table 3.1. Estimated Performance Parameters or the IEC Ion Thruster
Parameter IEC Ion Thruster
Propellant Xenon
Molecular Weight ( amu) 131.3
Specific Impulse (s) 3000
Thrust (mN) 34
Jet Power (W) 500
Net accelerating Potential (V) 600
Beam Current (mA) 832
Power Loss to Grid (W) <50
Power Loss to Bresstrahlung < I
Radiation (W)
Power loss to Ionization of 200-250
Propellant (W)
Input Power (W) 750-800
Thruster Efficiency (%) 62-68
In summary, the power efficiency of the IEC thruster appears to be competitive to
existing ion thrusters. What are the advantages then? These were outlined earlier and
include a more compact design, large heat rejection area, an exhaust jet closer to
quasi-neutrality, reduced neutral propellant leakage, and reduced grid erosion. Thus,
the mass of the IEC jet thruster system can potentially be reduced compared to a high-
power Hall-type thruster and also its lifetime can be increased significantly. In this
overall context, then, the IEC thruster potentially offers an important improvement in
performance for high power thruster applications.
Scale-up to p- 11B IEC Space Power Unit/Thruster
The electrically driven IEC jet thruster provides an important data base for a next step
p- 11B IEC jet thruster. Jumping to p- 11 B for this application may appear overly
ambitious. However, neutron less fusion seems essential in a small space thruster to
avoid excessive weight from shielding of electronics. Considerable experience with
fusing plasmas in IECs has been gained through development of IEC DD neutron
sources. These devices operate with ~ 80- keV D-ion beams using the non-Maxwellian
character of the IEC. This important characteristic makes use of p- 11B a realistic goal.
In fact, operation with circulating ion energies at the desired 150 keV energy for p- 11 B
has already been achieved at the UIUC and several other laboratories working on IECs.
The issue then is how to achieve adequate confinement times. The approach being
pursued at UIUC is the formation of deep potential wells with angular ion injection using
a differentially-pumped RF ion gun, as discussed in later sections. A proposed
experiment to demonstrate p- 11 B physics is discussed in Section VI.
In summary, the extraction of a jet plasma from a gridded IEC opens the way to a
number of added plasma applications for the IEC. This present discussion is intended to
identify an orderly progress of IEC applications in commercial space power, starting
with an electrically driven IEC thruster to a self-powered IEC p- 11 B unit. The attractive
characteristics of the electrically driven device, namely light weight, low maintenance,
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