5 ms·
>To overcome that barrier requires a sequence of particle collisions. First, an electron accelerator speeds up and slams electrons into a nearby target made of
by trhway 6y ago
>To overcome that barrier requires a sequence of particle collisions. First, an electron accelerator speeds up and slams electrons into a nearby target made of tungsten. The collision between beam and target creates high-energy photons, just like in a conventional X-ray machine. The photons are focused and directed into the deuteron-loaded erbium or titanium sample.
that way of X-ray generation is of very low efficiency. They should have put that deuterium loaded erbium, titanium (or Pt or Pd like in the famous cold fusion experiment) into the Sandia Z-machine. The typical target for the Z is either LiD or frozen D, and i wonder why they have never tried more heavy metals, especially Pt or Pd, loaded with D given how heavy nuclei is supposed to help in the fusion based on the cold fusion effects and which this NASA research seems to hint at too:
>But the lattice helps again. “The electrons in the metal lattice form a screen around the stationary deuteron,” says Benyo. The electrons’ negative charge shields the energetic deuteron from the repulsive effects of the target deuteron’s positive charge until the nuclei are very close, maximizing the amount of energy that can be used to fuse.
Honestly, my best bet is that Musk, who needs at least fission or even better fusion for Mars (space is the only business case for any plausible peaceful fusion), would soon start a venture for it. The inertial confinement, either Z-machine style or laser (modern lasers are much more efficient than NIF) is clearly the way to go, especially for space and when you need real result instead of large government sponsored research.
- raziel2701 6y agoThey don't use heavy metals because they strongly absorb X-rays, lower density materials are better at transmitting x-rays which is why they often use very low Z elements. Sometimes they dope with heavy metals but nothing has yet allowed to reach break even.
- trhway 6y agodefinitely, that is in general a factor. Though erbium and platinum doesn't differ that much than it come to X-ray attenuation. Additionally - the X-ray absorption by the lattice is important in the low energy level setting like that NASA experiment (basically equilibrium conditions) as any absorbed energy is basically lost and would just radiate away, whereis in high energy Z shot (non-equilibrium inertial confinement situation) the absorbed energy would still result in increased temperature and pressure of the target.
- CamperBob2 6y agoHonestly, my best bet is that Musk, who needs at least fission or even better fusion for Mars (space is the only business case for any plausible peaceful fusion) An interesting assertion. What are some of the reasons why you're certain that fusion will not be a useful source of energy in peacetime/civilian applications? Is it likely to be "too cheap to meter," as we were promised fission power would be, or do you think it'll always be too expensive to be practical?
- trhway 6y agoCheapest electricity is natural gas one. Imagine a natural gas plant with free natural gas. That would decrease the electricity price by about 1/3 (fuel price is up to 2/3 of natural gas based generation, and the generation is between half and 2/3 of electricity price). The fusion power plant ideally is equivalent of that free natural gas power plant. Though it can't be further from it on practice. Any feasible in the observable future fusion involves neutrons. That in addition to affecting reactor design - cost and complexity of building, operating and maintenance - brings in the whole regulatory regime just a notch lighter than fission. Taken together we'd be lucky to match the current natural gas - I personally think no chance in hell. Carbon emission of natural gas isn't an issue because nobody [who matter] cares about it today, and then, when the issue is finally forced for resolution, adding carbon sequestration would still be a comparatively minor expense. And that not even talking about already free fusion used in solar and wind based generation - hard to beat economics of that fusion reactor.
- DennisP 6y agoWhether fusion is expensive depends on the reactor design. There are a lot of possibilities. On one end of the scale is ITER, the giant tokamak they're building in France for tens of billions of dollars. At the other end is the petawatt laser boron fusion idea being pursued by HB11 Energy and various other researchers around the world. The main expense would be the laser at tens of millions of dollars.
- AtlasBarfed 6y agoFor power on the surface? Solar will do fine and is dead simple to setup. I have no specific knowledge, but I suspect there is some way to relatively easily manufacture solar cells on mars with minimal equipment, and that would be a much cheaper prospect that shipping a big nuclear plant to mars. Perovskites last I read are simple to make, and the atmosphere of mars may be far less corrosive with the lack of free oxygen. For propulsion? Nuclear rockets can't be used until you get out of the allen belts, otherwise fission product fall back to earth, it's really what submarined Orion as a concept. Pulse nuclear is probably the primary means for interplanetary transport if a sufficient manufacturing can be bootstrapped. In space stations / asteroid mining? Again solar is king without pesky atmospheres getting in the way. But once you have pulse nuclear ships flying around, it should be trivial to also have a thorium reactor for power.
- trhway 6y agopropulsion. Additional 3-4km/s of delta-V would allow to not be limited to those once-in-2-years launch windows and significantly decrease travel time. That would be a game changer on top of the game changer that the Mars bound Starship is already going to be. Nuclear launch from Earth isn't an option, yet Starship can easily launch a reactor into LEO, fission or fusion (fusion i think will even be more compact), and it can be used from there.