exchemist Posted February 14 Share Posted February 14 53 minutes ago, ALine said: how much does it cost to remove a neutron? Irrelevant. All you need to know is the binding energy per nucleon of the reactant species at the start and of the product species at the end and do the arithmetic. The route by which you carry out the change has no effect on the overall energy change between the two. What you are proposing is the reverse of the fusion people are trying to achieve with Tokamaks etc. You are turning a helium nucleus into 2 deuterium nuclei rather than the fusion process of turning 2 deuterium nuclei (or one deuterium and one tritium) into helium. Since that process releases energy, which is why people are trying to do it, your proposed process must necessarily absorb the same amount of energy. The binding energies per nucleon are shown on this graph, which shows the enormous gap between ²H and ⁴He: Link to comment Share on other sites More sharing options...
ALine Posted February 15 Author Share Posted February 15 15 hours ago, exchemist said: You are turning a helium nucleus into 2 deuterium nuclei rather than the fusion process of turning 2 deuterium nuclei (or one deuterium and one tritium) into helium. No, I am turning alpha particles into a proton pair and then waiting for them to fuse by applying energy. 21 hours ago, swansont said: The binding energy of He-4 is around 28 MeV and the resulting p-p system is not bound, so removing the neutrons costs you more than 28 MeV. As I said previously, the best you could possibly do is re-form the alpha and break even. If you have a naturally decaying radioactive source such as C-60 which emits gamma radiation then you would not need to worry about input energy. Its just naturally supplied. -1 Link to comment Share on other sites More sharing options...
Bufofrog Posted February 15 Share Posted February 15 1 hour ago, ALine said: No, I am turning alpha particles into a proton pair and then waiting for them to fuse by applying energy. The protons are already fused, at least for an instant or so. I have a question for you, if 2 protons fuse together what is the resulting product? 1 hour ago, ALine said: If you have a naturally decaying radioactive source such as C-60 which emits gamma radiation then you would not need to worry about input energy. That's true, but it has nothing to do with what we are discussing in this thread as far as I can see. 1 Link to comment Share on other sites More sharing options...
exchemist Posted February 15 Share Posted February 15 2 hours ago, ALine said: No, I am turning alpha particles into a proton pair and then waiting for them to fuse by applying energy. If you have a naturally decaying radioactive source such as C-60 which emits gamma radiation then you would not need to worry about input energy. Its just naturally supplied. But what's the point? All you do is make deuterium, which we can easily extract from seawater anyway, from alpha particles, by a process with <0.01% efficiency that consumes a lot of energy however it is supplied. What have you achieved? A net fission of helium into deuterium. What use is that? Link to comment Share on other sites More sharing options...
swansont Posted February 15 Share Posted February 15 2 hours ago, ALine said: If you have a naturally decaying radioactive source such as C-60 which emits gamma radiation then you would not need to worry about input energy. Its just naturally supplied I don’t think this would remove the neutrons*, but why use this for the fusion scheme? Why not just use the energy directly? *28 MeV total, but the first neutron would take more than half of that. Not that many >14 MeV gamma sources out there. Link to comment Share on other sites More sharing options...
ALine Posted February 15 Author Share Posted February 15 6 hours ago, Bufofrog said: I have a question for you, if 2 protons fuse together what is the resulting product? Deuterium 4 hours ago, swansont said: I don’t think this would remove the neutrons*, but why use this for the fusion scheme? Why not just use the energy directly? How would you extract energy from gamma radiation directly? Link to comment Share on other sites More sharing options...
swansont Posted February 16 Share Posted February 16 3 hours ago, ALine said: How would you extract energy from gamma radiation directly? Gammas could heat a material and you could harness thermal energy from thermocouples. Or photoionization could cause a current. How will you extract the energy from fusion? Link to comment Share on other sites More sharing options...
KJW Posted February 16 Share Posted February 16 (edited) On 2/15/2024 at 8:11 AM, exchemist said: Hmmm. I'm actually somewhat surprised that in the fusion from hydrogen to iron, the first step to helium provides about 80% of the energy (or am I interpreting the diagram incorrectly?). Edited February 16 by KJW Link to comment Share on other sites More sharing options...
exchemist Posted February 16 Share Posted February 16 13 minutes ago, KJW said: Hmmm. I'm actually somewhat surprised that in the fusion from hydrogen to iron, the first step to helium provides about 80% of the energy (or am I interpreting the diagram incorrectly?). That's how I interpret the diagram. Though one has to keep in mind this is binding energy per nucleon. What intrigues me, not being a nuclear physicist, is the spike at helium, and the smaller one at oxygen. These elements seem to have stability that lies off the curve. Are they filled nuclear shells or something? Link to comment Share on other sites More sharing options...
swansont Posted February 16 Share Posted February 16 4 hours ago, exchemist said: That's how I interpret the diagram. Though one has to keep in mind this is binding energy per nucleon. What intrigues me, not being a nuclear physicist, is the spike at helium, and the smaller one at oxygen. These elements seem to have stability that lies off the curve. Are they filled nuclear shells or something? Yes. He-4 is doubly magic and so is O-16 (filled shells at n=2, 8, 20, 28, 50, 82, and 126) 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now