Large-scale antimatter production

Question

From what I can find, presently the only known means of producing antimatter consist of directing particle accelerators at various targets, and only infrequently getting positrons or anti-protons as byproducts of particle interactions.

Assuming a sufficiently large source of energy: Have more efficient means of producing antimatter been conceived?

And based on these is there a known upper bound on antimatter production efficiency? For example:

1. If all known theory requires that an anti-particle be produced with its particle pair, then efficiency will always be under 50%.
2. Are there known processes for "transmuting" matter into anti-matter? If so, do these allow for a theoretical upper-bound on production greater than 50% of input energy?

Answer 1

This Centauri Dreams article claims that a 0.01% efficiency is possible with current technology if there was a dedicated production facility.

Having searched for information on this problem myself, I have found nothing more of significance.

If you can get past the google scholar paywalls, you may want to look through the articles by Robert Forward who is referred to as the source of the information.

Answer 2

The Sun produces upwards of 80 Tonnes of Antimatter a day, Anti-matter is a byproduct of ultra-high energy particle collisions. Positrons are ubiquitous in Solar dynamics. Solar flare volitility produces antimatter cascades in trace quantities. So a Catchment trap or "Ramscoop" could potentially harvest antimatter. Holding it, indefinite storage is the challenge. Another is ratio of efficient capture compared to Demand.

Answer 3

Magnetic field containers can be used for the storage of antimatter. Also, increasing the size of the particle accelerator will increase the volume output of antimatter, the key fuel in warp drives. The size of particle accelerator can be 100 miles around by diameter and 30 stories high.