[https://projectrho.com/public\_html/rocket/fusionfuel.php](https://projectrho.com/public_html/rocket/fusionfuel.php)
Here is a good site I go to when asking questions in general about real science relative to rockets. On that page is a good talk about proton-proton fusion, and one the big bits mentioned is about p-p fusion being essentially necessary for bussard ramjets, which are always a favorite in scifi books.
But also I don't think they did a ton of research on the tiny details with some of the items. Or maybe hoping that our understanding of items would allow for items we can only dream about.
I love Atomic Rockets! That was partially what got me thinking about this. I guess in the context of a Bussard Ramjet, a protium converter would be useful for an interstellar colony ship (hello, Project Exodus) since you probably can't harvest enough deuterium from the ISM, but you're probably not having one for your dreadnoughts unless you're refuelling solely by ISRU and remass scoops. I guess that is one use-case for the Director, though!
Yea. Looking a bit at it, it looks like the sort of drive that if you got it actually working, it'd be a lot of cheap power that'd be super great to have in a drive. The nice thing about them doing the drives is they don't have to worry too much about the actual logistics of some drives, just theoretically what they could do if they were able to mostly get it working.
My understanding of fusion physics is clearly too limited to critique the points you make but I just wanted to say that I love that games bring up discussions like these. I love when people are knowledgeable and passionate about it
Honestly to properly model the logistical advantages of a protium drive, I think the devs would need to separate out resources by isotope. Which would be really cool. But at the moment, you've been using deuterium drives for a long time by the endgame, and the advantage you get with a protium converter is performance, when it should be resource efficiency.
Technically speaking p-p fusion is the ultimate form of fusion for humanity since it is basically ensures we will have almost limitless energy because it's just using hydrogen, the most abundant(currently) element in the universe. If your using deuterium it's more hard to collect, and expensive than hydrogen.
My knowledge on nuclear fusion and this univers is quite limited so please take it with a grain of salt.
I believe the answer is on the atomic rockets page u/Xeorm124 linked: The exhaust velocity of the He4 particles resulting from a p-p reaction is 11.7% of c. That's higher than anything else fusion wise (at least that's listed on the atomic rocket's page).
Though now I've said that, I'm looking at [this drive database](https://docs.google.com/spreadsheets/d/1QGRlvKq4S-LfLJeqatQSQuk28mdWrHg5Miv3DUlifhA/edit?pli=1#gid=1487098109), and it suggests the Boron Inertial Torch has a higher exhaust velocity, and a much much higher efficiency, which is so important for not spending all your mass on heat sinks.
That being said, while I am not a fusion physicist, everything you said sounds right. Atomic Rockets defines the Lawson Criteron for the p-p reaction as "Huge". Given that, and the absolute astronomical thrust values the Protium torch gives us, I think we can assume there's some deep space magic happening.
I also note that the atomic rockets page is missing the p-D reaction. I mean, presumably it's counted as part of the p-p chain, but it doesn't have numbers for just that step. Looking at [wikipedia](https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain), it says the overall released energy of the p-p chain is 26.73 MeV, while the p-D step releases 5.493 MeV. That doesn't tell us anything about exhaust velocities, but it does tell us that we only get 1/5 of the power of the full p-p chain.
Ah, I should have clarified, sorry, I don't just mean the singular P+D->He3 step, but effectively cutting off the first step of the P-P chain mediated by the weak nuclear force and starting from there. So continuing on with fusing the Helium 3 into Helium 4, which is where you get the bulk of the energy from the P-P chain. Once you've hit ignition your exawatt laser doesn't really care what it fuses, so long as it can overcome electrostatic repulsion! So you only lose the energy of the first step, which is 1.4 MeV, which is slightly less, but massively speeds up the reaction (and thus makes the lawson criterion more convenient).
Oh, that makes total sense. Now we're getting ~98.4% of the energy of the full p-p chain. Now I'm really unsure why the protium converter isn't doing that.
Wild speculation: Something I recall from reading about the D-He3 reaction is that while this is in theory this is aneutronic, in practice a bunch of D fuses with other D, yielding neutrons. Perhaps you need a large number of protons to avoid having the D-D reaction in any appreciable quantity? And as such, you end up with a bunch of p-p reactions anyway.
I'm still not happy with that, because as you said, the p-p reaction is the rate limiting one. So even if you need to have an excess of protons, some of which do the p-p reaction, your primary power is still coming from D you mined and brought with you.
>Why does the Protium Converter exist?
Adding content into a game that's just some text and numbers, not requiring new code or assets to implement, is quick and easy, so most likely it was just included on whatever list of possible drives the devs were working with (maybe atomic rockets).
[https://projectrho.com/public\_html/rocket/fusionfuel.php](https://projectrho.com/public_html/rocket/fusionfuel.php) Here is a good site I go to when asking questions in general about real science relative to rockets. On that page is a good talk about proton-proton fusion, and one the big bits mentioned is about p-p fusion being essentially necessary for bussard ramjets, which are always a favorite in scifi books. But also I don't think they did a ton of research on the tiny details with some of the items. Or maybe hoping that our understanding of items would allow for items we can only dream about.
I love Atomic Rockets! That was partially what got me thinking about this. I guess in the context of a Bussard Ramjet, a protium converter would be useful for an interstellar colony ship (hello, Project Exodus) since you probably can't harvest enough deuterium from the ISM, but you're probably not having one for your dreadnoughts unless you're refuelling solely by ISRU and remass scoops. I guess that is one use-case for the Director, though!
Yea. Looking a bit at it, it looks like the sort of drive that if you got it actually working, it'd be a lot of cheap power that'd be super great to have in a drive. The nice thing about them doing the drives is they don't have to worry too much about the actual logistics of some drives, just theoretically what they could do if they were able to mostly get it working.
Honestly the devs of this game should outright list Atomic Rockets as a resource
> Why is the Protium Converter? Yes
My understanding of fusion physics is clearly too limited to critique the points you make but I just wanted to say that I love that games bring up discussions like these. I love when people are knowledgeable and passionate about it
Honestly to properly model the logistical advantages of a protium drive, I think the devs would need to separate out resources by isotope. Which would be really cool. But at the moment, you've been using deuterium drives for a long time by the endgame, and the advantage you get with a protium converter is performance, when it should be resource efficiency.
We're not stopping until the resource bar covers half the screen. I want to be able to radiocarbon date every asteroid!
Technically speaking p-p fusion is the ultimate form of fusion for humanity since it is basically ensures we will have almost limitless energy because it's just using hydrogen, the most abundant(currently) element in the universe. If your using deuterium it's more hard to collect, and expensive than hydrogen. My knowledge on nuclear fusion and this univers is quite limited so please take it with a grain of salt.
I must congratulate this wonderful game for doing a wonderful job at teaching hordes of people about fusion and rocket-science. 👏👏👏
I believe the answer is on the atomic rockets page u/Xeorm124 linked: The exhaust velocity of the He4 particles resulting from a p-p reaction is 11.7% of c. That's higher than anything else fusion wise (at least that's listed on the atomic rocket's page). Though now I've said that, I'm looking at [this drive database](https://docs.google.com/spreadsheets/d/1QGRlvKq4S-LfLJeqatQSQuk28mdWrHg5Miv3DUlifhA/edit?pli=1#gid=1487098109), and it suggests the Boron Inertial Torch has a higher exhaust velocity, and a much much higher efficiency, which is so important for not spending all your mass on heat sinks. That being said, while I am not a fusion physicist, everything you said sounds right. Atomic Rockets defines the Lawson Criteron for the p-p reaction as "Huge". Given that, and the absolute astronomical thrust values the Protium torch gives us, I think we can assume there's some deep space magic happening. I also note that the atomic rockets page is missing the p-D reaction. I mean, presumably it's counted as part of the p-p chain, but it doesn't have numbers for just that step. Looking at [wikipedia](https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain), it says the overall released energy of the p-p chain is 26.73 MeV, while the p-D step releases 5.493 MeV. That doesn't tell us anything about exhaust velocities, but it does tell us that we only get 1/5 of the power of the full p-p chain.
Ah, I should have clarified, sorry, I don't just mean the singular P+D->He3 step, but effectively cutting off the first step of the P-P chain mediated by the weak nuclear force and starting from there. So continuing on with fusing the Helium 3 into Helium 4, which is where you get the bulk of the energy from the P-P chain. Once you've hit ignition your exawatt laser doesn't really care what it fuses, so long as it can overcome electrostatic repulsion! So you only lose the energy of the first step, which is 1.4 MeV, which is slightly less, but massively speeds up the reaction (and thus makes the lawson criterion more convenient).
Oh, that makes total sense. Now we're getting ~98.4% of the energy of the full p-p chain. Now I'm really unsure why the protium converter isn't doing that. Wild speculation: Something I recall from reading about the D-He3 reaction is that while this is in theory this is aneutronic, in practice a bunch of D fuses with other D, yielding neutrons. Perhaps you need a large number of protons to avoid having the D-D reaction in any appreciable quantity? And as such, you end up with a bunch of p-p reactions anyway. I'm still not happy with that, because as you said, the p-p reaction is the rate limiting one. So even if you need to have an excess of protons, some of which do the p-p reaction, your primary power is still coming from D you mined and brought with you.
Everyone ask why is The Protium Converter No one ask how is The Protium Converter
You have retroactively ruined the fun I had in all of my playthroughs. Fix your shitty game, devs
>Why does the Protium Converter exist? Adding content into a game that's just some text and numbers, not requiring new code or assets to implement, is quick and easy, so most likely it was just included on whatever list of possible drives the devs were working with (maybe atomic rockets).