6 ms·
Coulomb explosion
- dvh 2y agoIt's the thing that makes sodium and potassium in water go bang!
- krasin 2y agoHere is the Nature paper that confirms the claim: https://www.nature.com/articles/nature.2015.16771 https://www.nature.com/articles/nature.2015.16771 Fantastic!
- cyberax 2y agoProbably not sodium. It's too unreactive for that. You've no doubt seen the sodium explosions, but what actually explodes is hydrogen, not sodium itself. If you run water+sodium reaction in an inert atmosphere, or simply weigh down a chunk of sodium so it quickly sinks to the bottom of the vessel, the result is much more tame. On the other hand, starting with potassium, you probable start to get enough charge separation to tear apart solid chunks of metal.
- sidewndr46 2y agoThere are those in the scientific community that disagree https://www.nature.com/articles/nchem.2161 https://www.nature.com/articles/nchem.2161
- gus_massa 2y agoThat was the comon explanation until Thuderf00t proved otherwise Video in YouTube: https://www.youtube.com/watch?v=LmlAYnFF_s8 https://www.youtube.com/watch?v=LmlAYnFF_s8 Paper in Nature Chemistry: https://www.nature.com/articles/nchem.2161 https://www.nature.com/articles/nchem.2161
- hristov 2y agoDoes anyone know weather this is actually being used in machining now. It seems that while lasers are being widely used in metal fabrication, they are the simpler heat ablation lasers. If it is being used in practice what are the advantages/disadvantages vis a vis edm?
- foota 2y agoThe only references I can find online seem to be for studying materials (e.g., https://www.scienceinschool.org/article/2024/explosive-imaging/ https://www.scienceinschool.org/article/2024/explosive-imagi...) and for nano machining (e.g., https://www.nature.com/articles/srep11313 https://www.nature.com/articles/srep11313), I wasn't able to find any commercial uses.
- osamagirl69 2y agoYou should upgrade your search engine. Here is a nice survey covering some of the commercial uses: https://www.photonics.com/Articles/Ultrafast_Lasers_Are_Quickly_Catching_Up_with/a66858 https://www.photonics.com/Articles/Ultrafast_Lasers_Are_Quic... The market for commercial femtosecond lasers systems is nearly $1B/year!
- foota 2y agoThese are just discussing femtosecond lasers, I don't see any mention of coulomb explosions? Maybe it's implied, but I don't see it.
- osamagirl69 2y agoThe working mechanism of femtosecond (and picosecond for that matter) micromachining is the same as the coulomb explosion being discussed here. In the industry it is usually referred to 'athermal' or 'cold' to differentiate from the older system which rely on thermally heating the material to ionize it. In fact it is mentioned explicitly in the wikipedia article: >Coulomb explosions for industrial machining are made with ultra-short (picosecond or femtoseconds) laser pulses...Coulomb explosion etching can be used in any material to bore holes, remove surface layers, and texture and microstructure surfaces
- foota 2y agoIt sounds like you're familiar with the field, so I'll accept that you're probably correct here, but the wikipedia article doesn't say what you're claiming. It says coulom explosions are made with ultra short lasers, not that all ultra short laser pulses result in coulomb explosions, so for someone that doesn't know otherwise, you can't infer that whenever someone says ultra short laser cutting that it happens via coulomb explosions.
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- runamuck 2y agoYou can use a Columb exemplar algorithm for an alternate to K-means. According to several white papers (Duta) it learns faster with fewer exemplars.
- StableAlkyne 2y agoI'm having trouble finding anything about this algorithm online, would you be able to link a review or one of those white papers you mentioned?
- krick 2y agoWould be nice to see some more concrete data/references. This is a big claim. I mean, if it is "basically the same" but "faster and requires fewer examples" you can just say that it's "strictly better" than K-means, and stop using K-means ever. However, everybody is aware of K-means and personally it's the first time I hear about "Columb exemplar algorithm".
- didgeoridoo 2y agoReminded me of this great post from a while back, “What if I were 1% charged?”[0] looking at the consequences if you were to remove one out of every 100 electrons in your body. The answer: a Coulomb explosion powerful enough to rip the vacuum and generate antimatter from the void. [0]: https://gravityandlevity.wordpress.com/2013/05/22/what-if-i-were-1-charged/ https://gravityandlevity.wordpress.com/2013/05/22/what-if-i-...
- pfdietz 2y agoThis is why non-neutral plasma schemes aren't a road to fusion: the densities that could be practically achieved are extremely low.
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- wrycoder 2y agoIt turns out that the great majority of the energy in a fission explosion is partitioned into a Coulomb explosion of the fissile material.