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Post by Kerr on Jun 7, 2017 18:23:42 GMT
Does anyone know how many electron volt a deuterium helium 3 reaction needs?
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Post by bigbombr on Jun 7, 2017 18:44:40 GMT
Antimatter has a few other issues, not just production cost. It decays with bombardment by cosmic rays, it requires constant uninterrupted power for containment, and storage facilities may explode with containment breaches. So it's less likely to be used soon, compared to simpler technologies. The real draw of antimatter would be if we have antimatter factories in low sun orbit running off solar panels. My craft would be able to propel itself outside the solar system (slowly). It would be much easier to refuel if it's supposed to do something meaningful for long times over there (Really needs only fissile and propellant, and it can use almost anything salvaged as propellant to scoot around its target system). IIRC, the spot size was something like 40 meters radius at 10 Gm (with ~39 GW beam power). Which would work fine, if the craft has a mirror of that size on its rear end, focusing the big spot down into its thruster into a centimeter or so (which was my intention). There's no need to ignite a pellet directly from 300 Mm. The craft has over 80 tons of mass tied up in the crew module (for 30 people, which is clearly overkill; it may even be unmanned if we get good enough AI). Some of that mass would be repurposed for things like the back mirror, and spare fuel rods for the reactor. 1g of Antimatter will get hit by an average of 11,5 eV cosmic radiation per second, this means it will get hit every 100 days with a low energy cosmic ray (100 MeV). Yup, low sun orbit are a good thing. One hectare at mercury's distance can generate 2,4µg per day. 2,4g need 10 thousand square kilometers of solar panels, With a efficiency of 27%. 80 tons don't sounds overkill, if you consider that these people have to eat food and drink water everyday. Other than that, your design sounds solid, the immense infrastructure requirements might the very expensive but might pay out in the long run. Laser thermal for civil and trade and Antimatter Fusion for military purposes? But if you have this much of laser infrastructure, wouldn't a lasernet make most combat spacecraft obsolete? A diffuse net of laser emitters, mirror drones and recon drones would seem much harder to disable than a craft you can blow in half by sneezing on the antimatter containment too harshly.
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Post by Kerr on Jun 7, 2017 18:50:30 GMT
1g of Antimatter will get hit by an average of 11,5 eV cosmic radiation per second, this means it will get hit every 100 days with a low energy cosmic ray (100 MeV). Yup, low sun orbit are a good thing. One hectare at mercury's distance can generate 2,4µg per day. 2,4g need 10 thousand square kilometers of solar panels, With a efficiency of 27%. 80 tons don't sounds overkill, if you consider that these people have to eat food and drink water everyday. Other than that, your design sounds solid, the immense infrastructure requirements might the very expensive but might pay out in the long run. Laser thermal for civil and trade and Antimatter Fusion for military purposes? But if you have this much of laser infrastructure, wouldn't a lasernet make most combat spacecraft obsolete? A diffuse net of laser emitters, mirror drones and recon drones would seem much harder to disable than a craft you can blow in half by sneezing on the antimatter containment too harshly. Good luck hitting the containment chamber the size of an medicine ball. The can disable all these mirrors with sandblasters way outside the range of the lasers. And the laser will most likely have no thrusters, and if so, they won't use them randomly just to avoid being hit a extremely fast sand.
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Post by RiftandRend on Jun 7, 2017 22:34:00 GMT
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Post by RiftandRend on Jun 7, 2017 22:40:31 GMT
But if you have this much of laser infrastructure, wouldn't a lasernet make most combat spacecraft obsolete? A diffuse net of laser emitters, mirror drones and recon drones would seem much harder to disable than a craft you can blow in half by sneezing on the antimatter containment too harshly. Good luck hitting the containment chamber the size of an medicine ball. The can disable all these mirrors with sandblasters way outside the range of the lasers. And the laser will most likely have no thrusters, and if so, they won't use them randomly just to avoid being hit a extremely fast sand. A PW solar powered laser array can probably destroy anything in the solar system with ease. At that beam power it could likely ablate any projectile long before it is hit and destroy any laser platform preemptively rendering it nearly invulnerable.
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Post by Enderminion on Jun 7, 2017 22:52:58 GMT
Good luck hitting the containment chamber the size of an medicine ball. The can disable all these mirrors with sandblasters way outside the range of the lasers. And the laser will most likely have no thrusters, and if so, they won't use them randomly just to avoid being hit a extremely fast sand. A PW solar powered laser array can probably destroy anything in the solar system with ease. At that beam power it could likely ablate any projectile long before it is hit and destroy any laser platform preemptively rendering it nearly invulnerable. you don't know where the AM is in the ship
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Post by acrosome on Jun 7, 2017 22:55:52 GMT
proton -Boron11
Because boron.
Obviously.
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Post by RiftandRend on Jun 7, 2017 23:16:28 GMT
A PW solar powered laser array can probably destroy anything in the solar system with ease. At that beam power it could likely ablate any projectile long before it is hit and destroy any laser platform preemptively rendering it nearly invulnerable. you don't know where the AM is in the ship What? How is that relevant?
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Post by Fgdfgfthgr on Jun 7, 2017 23:19:45 GMT
proton -Boron11 Because boron. Obviously. That is!
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Post by The Astronomer on Jun 7, 2017 23:24:41 GMT
proton -Boron11 Because boron. Obviously. Guys, be serious. I want accurate data of your preference, and I don't want to see another 'I HAIL MY GOD' situation here.
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Post by Kerr on Jun 8, 2017 4:39:54 GMT
Good luck hitting the containment chamber the size of an medicine ball. The can disable all these mirrors with sandblasters way outside the range of the lasers. And the laser will most likely have no thrusters, and if so, they won't use them randomly just to avoid being hit a extremely fast sand. A PW solar powered laser array can probably destroy anything in the solar system with ease. At that beam power it could likely ablate any projectile long before it is hit and destroy any laser platform preemptively rendering it nearly invulnerable. Ever heard of light lag? And how do you even know where something the size of a grain of sand is?
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Post by Kerr on Jun 8, 2017 4:41:05 GMT
For peak fusion rate yes, D-He³ Fusion start at 30 KeV.
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Post by Kerr on Jun 8, 2017 4:46:35 GMT
Hmm, DT fusion is 5x worse than D-He³ in producing thrust, at the same time, D-He³ needs 5x more energy for maximum fusion rate.
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Post by RiftandRend on Jun 8, 2017 7:17:30 GMT
Hmm, D-T fusion is 5x worse than D-He³ in producing thrust, at the same time, D-He³ needs 5x more energy for maximum fusion rate. My ingame tests suggest otherwise. D-T fusion gets ~11 kN per GW of input power and ~13 Mm/s exhaust velocity. D- 3He fusion gets ~4.5 kN per GW of input power and ~20 Mm/s exhaust velocity. This is assuming no ignition, so the data may be significantly skewed in favor of D-T fusion.
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Post by RiftandRend on Jun 8, 2017 8:29:41 GMT
Alright, I made something vaguely approximating antimatter ignited fusion.
I calculated the amount of hydrogen-antihydrogen (~1.88 GeV per reaction) needed to supply all the activation energy for the fusion reaction. When setting up the reaction I realised you can't have anything other than whole numbers for the reactants (0.000031914889364691285907185429147361 moles of H- H mix per mol of D-T mix). Unfortunately I couldn't set up the reaction the other way (having ~99,996,808,511,063,530,871,409,281,457,085 moles of D-T mix per mol of H-H mix) because of a 9 character cap on reactant counts.
As a consequence, this reaction uses about 100,000,000,000,000,000,000,000 times as much antimatter as it should, but that's be best I could come up with.
Element Antihydrogen Symbol H- AtomicMass 1 AtomicNumber 1 MolarMass_g__mol 1.0079 IsANonmetal true FirstIonizationEnergy_kJ__mol 1312.0 MicroscopicThermalNeutronCaptureCrossSection_b .294 MicroscopicThermalNeutronScatteringCrossSection_b 28.966 MicroscopicFastNeutronCaptureCrossSection_b 3.96e-5 MicroscopicFastNeutronScatteringCrossSection_b 3.99 MicroscopicResonanceIntegralCaptureCrossSection_b .149 MicroscopicResonanceIntegralScatteringCrossSection_b 240.23 SolarAbundance 0 Emission Hydrogen
Material Antihydrogen-Hydrogen Mix (Fusion) Elements H H- ElementCount 0.999999999999999999999999 .000000000000000000000001 Density_kg__m3 70.85 EnthalpyOfFormation_kJ__mol 0 BondDissociationEnergy_kJ__mol 435.7799 GibbsFreeEnergyOfFormation_kJ__mol 0 BulkModulus_GPa .1130 MeltingPoint_K 14.01 BoilingPoint_K 20.28 SpecificHeat_J__kg_K 14310 ThermalConductivity_W__m_K .1085 Viscosity_Pa_s 8.76e-6 RelativePermeability .9999999751 DielectricStrength_MV__m 1.95
RefractiveIndex Hydrogen Material Deuterium-Tritium Mix (Fusion) Elements T D ElementCount 1 1 Density_kg__m3 191.2 EnthalpyOfFormation_kJ__mol 356022182 BondDissociationEnergy_kJ__mol 446.67 GibbsFreeEnergyOfFormation_kJ__mol 0 BulkModulus_GPa .1130 MeltingPoint_K 19.68 BoilingPoint_K 24.36 ThermalConductivity_W__m_K .13007 SpecificHeat_J__kg_K 7763.5 Viscosity_Pa_s 12.6e-6 RefractiveIndex Hydrogen
ChemicalReaction Antimatter Boosted Fusion Deuterium Tritium Reactants Deuterium-Tritium Mix (Fusion) Antihydrogen-Hydrogen Mix (Fusion) ReactantCounts 999999999 1 Products Helium ProductCounts 999999999 ActivationEnergy_kJ__mol 5789119 AutoignitionTemperature_K 696271500 CharacteristicLength_m 50
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