Defense Intelligence Reference Document Inertial Electrostatic Confinement Fusion

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Figure 4 is a schematic sketch of the ion injectors shown in Figure 6.3. A key
component is the magnetic focusing lens at the gun extraction port. This allows very
efficient differential pumping between the high pressure gun chamber and the low
pressure IEC chamber and provides focus control. This experiment will involve very
high power inputs (about a MW). To avoid excessive power supply and thermal
controls, a Marx bank pulsed power input with peak powers of~ 1 MW over 1 msec at
0.01 Hz will be used. Pulsed experiments with equivalent power inputs on one gun have
already been performed successfully. The pulse length is set long enough to provide
quasi equilibrium physics conditions in the trapped plasma during the "flat top" region
of the pulse". Thus the data obtained is relevant to eventful steady-state reactors
where the internal fusion power production alleviates the input power supply
requirement.
The energy gain (Q) scaling for such a device goes as ~I/a 2 where a is the radius of the
dense core spot formed in the IEC sphere, ~ is the number of ion recirculations in the
trap before the ion is lost, and I is the ion injected current. The 12 gun breakeven
design will provide an increase in ~ to ~ 1000 due to differential pumping effects, I will
increase to 6000 mA (due to multiple pulsed guns), and a will be cut down by 10 due to
improvements in focusing both and reduced collisionality. This predicts an increase in Q
(compared to prior gun experiment) of ~108 , giving Q=l ("breakeven") as required for
a p- 11B plasma (as noted earlier, this breakeven Q assumes a Lawson breakeven
confinement parameter of nT that exceeds the DT requirement by a factor of 100. In
other words, this could also be thought of as a Q=100 DT equivalent breakeven!) Such
an experiment would provide a physics proof-of-principle for this ion injected IEC
concept and provide the base for extending this configuration on to a power-producing
plant.
To accomplish this result quickly on a modest budget, we need to simplify the work by
avoiding the need to develop new injection technology for hydrogen-boron fuel plus
avoid the need to handle the fusion energy produced. Thus we propose to confirm the
achievement of breakeven conditions using a hydrogen plasma and diagnostics to show
that the nT and T corresponding to Q = 1 (p- 11 B) are obtained. (An alternate approach
might be to use deuterium as is done in present IEC neutron source studies. However,
that would require a massive shielding and other access restrictions for the neuron flux
levels). Modern plasma diagnostics can make quite precise measurement of the plasma
conditions needed for the confirmation, so the hydrogen equivalent approach is
recommended.
CONCLUDING REMARKS
Once achieved in hydrogen, these conditions could be fairly quickly confirmed with p-
11 B fuel in later experiments once the needed fuel handling system is added. Thus the
proposed hydrogen simulation of p- 11B breakthrough conditions would be a landmark
achievement, leading the way to rapid deployment of the technology needed to build
small fusion power plants. The technology development needed to proceed largely
involves the design and engineering of subsystems for the balance-of-plant (BOP).
Many of these can employ conventional equipment, but several require new
developments. These include the hydrogen-boron fuel injection system, the direct
energy conversion system to convert the charged particle product energy to electricity,
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