In March 2020, Positron Dynamics completed a new source installation at Berkeley. They continue to make progress on experiments and designs.
Positron Dynamics designs avoid huge show-stopper problems with using antimatter.
We cannot store useful amounts of antimatter.
We can only generate tiny amounts of antimatter.
Antimatter particles that are created need to be slowed down for use.
It would be very difficult to develop the designs for antimatter propulsion into actual working systems.
Positron Dynamics will use Krypton isotopes to generate positrons. They would breed more Krypton isotopes. They sidestep the issue of antimatter storage. The designs that they have seem to have more manageable problems and they are able to get to actual lab experiments.
It would take 10 school buses of volume at the Brillouin limit to trap 1 microgram.
They are slowing the positrons that are generated.
Krypton 79 isotope to generate hot positrons.
Use their system to moderate the positrons so they can be used.
They then use the Positrons to catalyze nuclear fusion. Neutrons from nuclear fusion can then breed more Krypton 79.
They have done momentum transfer and deuterium loading experiments.
There would be 1-10% momentum transfer from catalyzed fusion propulsion.
They need one trillion positrons to generate nuclear fusion events according to the Lawson Criteria.
Energy balance and 2-D pic models indicate maybe 100 billion positrons would be needed.
They have worked on the isotope breeding. They needed to get the Krypton densified. The amount of Krypton 79 that can be generated is limited by source geometry.
They have a system designed for an 100-ton asteroid capture mission with a delta-V of 60 kilometers per second. It would be 20 times lighter than NASA solar electric mission.
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The Orion programme was't practical because it bathed the astronauts in radiation from the explosions, and because it contravened the Nuclear Test Ban in Space . Even if Orion had gotten off the ground top speeds were reckoned to be no higher then this Positron technology, if it works, i.e 10-20% of light speed. The bigger players, e.g Tesla or Nasa are currently focusing on better rocket engines using solid fuels rather then new technologies like this. But the higher speeds could make the technology very valuable, for inter solar system exploration and and commercialisation of resources in OUR solar system, e.g Asteroid Mining ect.
Hi people, im a time traveller from the year 2769, i can gladly announce that we have mastered fusion and antimatter.
The short bus…definitely the short bus.
Could you use fission to breed the Krypton 79?
Oooh, a new SI unit, the ‘School bus’ of volume. Is that one of the old yellow ones, or the fancy new ones with big comfy seats? Or maybe a short one?
http://www.nextbigfuture.com
Orion wasn’t antimatter. It was nuclear pulsed propulsion, using cheap fission bombs if I recall correctly.
True, and you would likely know better than I would. I keep thinking back to the studies done of anti matter Orion drive that was estimated to be able to reach up to a significant percentage of light speed. I have not seen another propulsion system capable of that kind of speed yet for large mass craft. If we want to reach other solar systems, even “close” ones in human significant time frames I believe we need to go with our most powerful drive concepts.
This is less antimatter propulsion, than antimatter initiated solid state fusion.
I’ve personally got doubts about this; Every step before the fusion is really lossy, so they’re going to have to demonstrate a REALLY high gain in the fusion step to be better than just directly using the radiation from the radioisotope for thrust.
Granted, antimatter technologies seem to be out of our reach at the moment. However, antimatter is energetic on a scale we cannot duplicate with other propulsion systems. If we want to eventually move large masses into other solar systems in human significant time frames it seems to be our best bet.