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The Exotic Technologies Institute Grants for Bussard Ramjet Propulsion System The next propulsion system grant candidates are ingenious extension of many
spacecraft types including the Bussard interstellar ramjet
propulsion systems. The ramjet concept can provide, potentially, a highly effective form of interstellar
propulsion. The American physicist Robert Bussard first suggested it in 1960. Consequently
is sometimes referred to as the Bussard ramjet. Set against the desirability of achieving speeds for star travel that are
a significant fraction of the speed of light is the perennial problem of rocketry
-- having to carry, in addition to the payload, the reaction
mass needed for propulsion. The interstellar ramjet neatly avoids this problem by harvesting hydrogen for use as
a propellant from the interstellar medium. The captured hydrogen is fed to a nuclear fusion reactor, which supplies the energy for a high-speed exhaust. Bussard's original
design envisaged atomic hydrogen being mechanically scooped up by the spacecraft as it went along. However, his calculations suggested that, in order to achieve the "ideal" acceleration
of 1g in typical regions of interstellar space where the density of hydrogen atoms
is about ~1 H-atom/cm², a 1,000-ton spacecraft would need a frontal collecting area of nearly 10,000 square km. (In interstellar
clouds where the average density is ~10² H-atoms/cm², a scoop with one-tenth this area would suffice.) Even assuming knowledge
of materials science far in advance of our own, it seems inconceivable that such a scoop could be constructed with a mass
less than that budgeted for the entire vehicle. A 10,000-square-km structure made of 0.1-cm-thick Mylar, for example, would
weigh about 250,000 tons. A way around this problem is to ionize the hydrogen ahead of the spacecraft using a powerful laser.
A relatively small Bussard collector that generates a powerful magnetic field can then draw in the hydrogen ions --naked protons
--. Since the harvesting process is electromagnetic rather than mechanical, the scoop does not have to be solid (it can be
a mesh) nor does it have to be unrealistically large, because the field can be arranged to extend far beyond the physical
structure of the scoop. The enormous power needed to generate the Bussard collector's
magnetic field and to operate the ionizing laser. Another problem concerns the way the ram scoop works. As the lines of the
magnetic field converge at the inlet funnel, they will tend to bounce away incoming charged particles rather than draw them
in. In effect the scoop will act like a magnetic bottle, trapping material in a wide cone in front of the vehicle and preventing
it from being injected as fuel. A solution might be to pulse the magnetic field, but the implementation would not be easy.
Yet another problem is that most of the collected matter will be ordinary hydrogen, which is much harder to induce to fuse
than either deuterium or tritium, hydrogen's heavier isotopes. Finally, the Bussard
ramjet will only work when the vehicle is moving fast enough to collect interstellar mass in usable amounts. Therefore a secondary
propulsion system is needed to boost the spacecraft up to this critical speed -- about 6% of the speed of lightA A modified
design, known as RAIR (ram-augmented interstellar rocket), proposed by Alan Bond in
1974, tackles the fusion-reaction problem by using the scooped-up interstellar hydrogen not as fuel but simply as reaction
mass. The incoming proton stream is decelerated to about 1 MeV, then allowed to bombard a target made of lithium-6 or boron-11.
Lithium-proton or boron-proton fusion is easy to induce and releases more energy than any other type of fusion reaction. The
energy produced in this way is added to the mass stream, which then exits the reactor. In the exhaust nozzle, the energy created
by initially breaking the mass stream is added back to itThe so-called catalyzed-RAIR offers an even more efficient approach.
After the incoming mass stream has been compressed, a small amount of antimatter is added. The reaction cross-section is not
only enormous compared to fusion, it happens at much lower temperatures. According to one estimate, the energy release is
such that the drive reactor of a 10,000-ton antimatter catalyzed-RAIR accelerating at 1g and maintaining 1018 particles
per cubic cm within the reactor only has to be about 3.5 m in diameter. The down side is that large amounts of antimatter
would be needed for sustained interstellar flight.The Exotic Technologies Institute can provide grants for Bussard interstellar ramjet propulsion systems and RAIR propulsion systems R&D studies. Both
cases space craft propulsion systems grants can used designs using table top laser systems for interstellar ramjet propulsion
system and nanotechnology based ramjet scoop designs for the interstellar ram jet concepts. Construction materials made of
nanotechnology is potentially a source of very lightweight construction materials for alternative energy systems and aerospace
industry. Nan technology construction materials have structural strengths bordering
on the amazing -that’s up to one hundred times stronger than steel. In effect nanotechnology construction materials
is tough and strong as a diamond. A single piece of nanotechnology product can
be stretch up to 250,000 miles. Lightweight nanotechnology construction materials are being in the recently NASA funded multimillion
space elevator project. Therefore nanotechnology construction materials can be used for large scale space colonies, interstellar
ramjet ram scoop, aircraft and space craft .The above table top laser systems can be used to provide laser heat energy for
the potential Bussrad interstellar ramjet propulsion system. The small-scale grants can be used for personnel budgets, operating
costs and general budgets. The large-scale grants can be used to create small-scale
interstellar ramjet scoop engines protypes. These rocket engine protypes can be based interstellar ramjet scoop engines composed
of nanotechnology and tabletop laser systems.
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