Draper Laboratory: Extraction of Antiparticles Concentrated in Planetary Magnetic Fields

Instapundit has a link to the antimatter story that NBF covered last week.  This reminds me that I wanted to post something else about it.

So, I pulled up the pdf that the BBC story references.  Here is a pic I copied from the file, an antimatter collector.

Ultimately, these natural fluxes can be concentrated and the antiparticles trapped
for use in space propulsion and/or other innovative applications.

bullet notes

• high energy galactic cosmic rays (GCR) bombard the upper atmosphere of
  planets and material in the interstellar medium to naturally generate antiparticles through pair production
• There are four fundamental processes that can cause antiprotons to be concentrated in or around planetary magnetic fields. They are:

1. Cosmic Ray Albedo Antineutron Decay (CRANbarD)
2.  Direct pair production and trapping of antiprotons in the exosphere
3. Transient GCR focusing
4. Artificial augmentation

• A natural antiproton radiation belt can be generated in a manner analogous to the traditional Van Allen radiation belts which surround the Earth.
• The magnetic field of the planet forms a bottle to stably hold the protons and electrons from the decay process.
• At radiation belt altitudes, this loss rate is extremely slow enabling a large supply of generated antiprotons to be built up relative to the source flux.
• Based on this and the subtraction of the solar proton contribution, the antiproton content of the Earth’s magnetosphere from this effect is estimated to be between 0.15 and 15 nanograms.
• A 100 kWe generator would produce approximately 10 micrograms per year. Scaling this to a 1 GWe power source would enable nearly 100 milligrams of antiprotons to be produced per year. This level of antiproton generation is sufficient to enable the first interstellar missions to nearby stars. 

Inasmuch as I suggested using an energy beam to power a spacecraft, such as VASIMR, there is another possible use for this antimatter- as an energy source employed in a like manner.

Why?  Well, antimatter is dangerous.  It would be better to not carry it onboard a spacecraft for a long period of time.  Things go wrong.  Why not use it, then, as a concentrated power source to move a spacecraft that way, instead of inducing explosions and so forth?

Also, how do you get 1 GWe into space?  You could beam the power up from the moon, then use that power to capture the antimatter, which will amplify the power enormously.