Particle accelerators for the microchip era | Hacker News Reader

Particle accelerators for the microchip era

moore.org

111 pointssharpshadow13 comments

A problem with all these advanced acceleration techniques is beam quality. I'd worry imperfections in the microfabricated device would cause this to degrade. Imperfections become increasingly important as the device is miniaturized; in a 1 micron device, an offset of a single atom's width is .01%.

I've known Dr. Byer for years and years. A great guy. So glad that he and his team at Stanford are getting due recognition for this work.

Agreed, he's an amazing man. He was on my Qualifying Exam committee....and I presented on dielectric laser accelerators. Apparently I didn't butcher it.

I'm glad the effort is progressing and getting recognition! It would be really cool to see a lot of microfabricated accelerators out in the wild. There are lots of applications for these things and it would unlock a lot of value for the world.

Any startups trying to commercialize these?

Not that I know of. I was adjacent to this work about 9yrs ago but have tracked it since. The technology is still too early and too risky to work on commercializing. Amazingly though, one of the lowest energy (read easiest, but still hard. The technology is not there yet.) applications is for use as a targeted radiation source for cancer therapies. This paper[0] covers that a little bit and offers a few other applications. I recall seeing a paper that proposed different applications at different energy levels. I'll see if I can dig it up.

[0] https://www.slac.stanford.edu/pubs/slacpubs/16750/slac-pub-1...

No information on what kind of energy levels these can achieve? i.e., keV or MeV?

"Using a more sophisticated silicon structure, still for subrelativistic electrons (96.3 keV), the highest gradient achieved is 370 MV/m over a 5.4 μm interaction length in the dual pillar silicon structure with two-sided illumination"

— Source: https://opg.optica.org/oe/fulltext.cfm?uri=oe-30-1-505&id=46...

I heard about photon rockets, I heard about ion drives, but an electron rocket motor is new. Can't be bothered to do the math here but Isp doesn't sound too bad eyeballing it...? 1 eV is 5.94 × 10^6 m/s but multiplying this by 96.3k looks like it needs a relativistic correction.

We've got no shortage of electron beams to use in an engine. The problem is that the engine runs out of electrons very quickly and will become positively charged. Meaning all your propellant will come flying back. You would have to capture 'free' electrons from space to make use of it.

"These on-chip devices accelerate sub-relativistic electrons of initial energy 83.4 keV by 1.21 keV over 30 μm, providing peak acceleration gradients of 40.3 MeV/m." (Sapra et al. Science 2020)

Lasers on a chip plus photonic waveguide technology, oh my!

https://arxiv.org/pdf/1905.12822

[edit this is an earlier version see other comment]

The continued shrinking of accelerators has had me brainstorming on a compact nanofusion approach for awhile

https://docs.google.com/document/d/1B5maRx9w0ahQTqSe6UZ56rd0...

You might want to also look at what can already be done with an electrostatic design such as a fusor, and why they aren't widespread outside of science fair projects.

Another limitation with anything micro-fabricated is that the resulting radiation from fusion working is going to knock atoms out of their lattices, degrading chips in direct proportion to total (lifetime) energy output.

Yeah, I did a bit but thanks for the thought. Will again

Agreed the micro architecture and energies involved are.. challenging

I guess my thinking is that most of the assumptions that might have precluded small scales may have radically changed

I'm thinking of the lattice as more of a staging area for a downrange scatter, so no local accumulation of the energies. But no idea how practical that may be

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