AAWSAP DIRD, Positron Aerospace Propulsion, March 2010

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UNCLASSIFIED/;'FOR OFFl@IAL YSE OHLY
where k' is characteristic of the electron density for silica strands= 0.0164 nm-ns-1, R
is the void radius (nm), r' is the silica strand thickness (0.68 nm), AT is the self­
annihilation rate, and Aq is the quenching rate for air (0.00427 ns-1 at 0.1 torr vacuum,
typical of a standard rotary pump). To illustrate, without magnetic and electric fields (AT
= 1/142 ns = 0.007 ns-1) and for R = 20 nm, A= 0.0121 ns-1, or -r = A-1 = 82.5 ns. This
is consistent with our measurements.76
Assuming self-annihilation is suppressed (AT~ 0) by crossed magnetic and electric
fields, a high vacuum c10-s torr) is maintained (Aq ~ 0) and R = 20 nm, then A = 8.5 x
10-4 ns-1, or t = 1.2 µs. Proprietary experiments at Positronics Research LLC show that
Ps atoms in crossed magnetic and electric fields in silica aerogel with 20-nm voids live
up to 10 µs. This is somewhat longer than the predicted lifetime owing to severe
radiation damage induced in the silica aerogel by positrons that alters k' from the
values quoted above.
Measured lifetimes in the present experiments at Positronics Research LLC are within
limits set by diffusion to the trap walls. This is consistent with the expectation that Ps
atoms "stabilized" in crossed magnetic and electric fields will be "delocalized" and drift
freely across magnetic field lines.
Future experiments at Positronics Research LLC will use super-dilute media (R = 1,000
nm), large container volumes (10 cm), weak magnetic fields (< 0.1 Tesla), and electric
fields. Substitution of R = 1,000 nm into Equation 2, assuming again a high vacuum
and crossed magnetic and electric field suppression of self-annihilation, predicts a
lifetime of 61 milliseconds. Assuming the following results are consistent with this
prediction, it will be demonstrated beyond any reasonable doubt that Ps can be
stabilized against "self-annihilation" in crossed fields.
To ultimately reach lifetimes of months and years required by aerospace propulsion,
oscillating electric-gradient-field-confinement forces will be required to keep Ps atoms
off the walls of a high-vacuum trap. Ps atoms will be produced by a beam of low-energy
positrons intercepting silica aerogel and be stabilized in the trap using crossed magnetic
and electric fields. Ps in crossed magnetic and electric fields has an enormous electric
dipole moment, and confinement using the classical p•VE force looks very encouraging
at this time.
Conclusions
Conceptual designs and missions for turbojets, turbo-ramjet missiles, and
interplanetary rockets powered by positron annihilation have been presented. Positron
requirements range from 150 micrograms for a globe-encircling UAV turbojet flight to
100 milligrams for a mission to Mars. A positron-powered SSRV could take off from
Earth horizontally, go to LEO, launch to Mars for a 1-year exploration of the Red Planet,
and return to LEO and then Earth with a horizontal landing without refueling.
Within 10 years, the 150 µg of positrons required for a globe-encircling, nonstop
turbojet flight could be made in 6 months at a cost of $69 million. This first-ever
antimatter voyage, approximately 90 years after Lindbergh's 1927 Spirit of St. Louis
transatlantic flight, would stir the public's imagination and eventually lead to positron­
powered exploration of the solar system in the 21st century.
UNCLASSIFIED/fFOA OFFICiIAk Wlilii 0PU.Y
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