Deep in the heart of me - the tech of the Iron Man movie
Going to start posting here again, partly because I've already friended some folks on LJ and partly because of the ease of doing an lj-cut.
Anyway, I've been Googling commentary on the Iron Man movie, specifically the major technological MacGuffin - the arc reactor. And nobody seems to have put as much thought into it as me. Maybe that should tell me something...
All the rest of the Iron Man technology - boot jets, repulsor beams, everything - hinges on the energy output of Tony Stark's miniaturized arc reactor. The prototype built in the cave is quoted as putting out '3 gigajoules per second', otherwise known as 3 gigawatts, of power - but it's then immediately made clear that that's a peak output for a limited time only, since he says it can power something big for '15 minutes'.
The device is small, so it basically needs to be some type of nuclear energy or something even more exotic, such as matter-energy conversion or zero-point energy. The original, mammoth arc reactor back at Stark Industries looks like some kind of glass-walled tokamak, which points us towards fusion, and the central ring of the miniature version is made of palladium, clearly meant to imply a connection of some kind with the Pons/Fleischmann cold fusion fiasco. So, say it's some type of nuclear fusion - that would produce the required amount of energy while only 'burning' milligrams of hydrogen (which could be extracted from water vapor in the atmosphere, or from a tiny reservoir of water not shown, or infused in the palladium core - palladium is also being looked at for hydrogen storage, although I'm not sure 2 grams of the stuff could hold enough hydrogen to do 3 gigawatts for 15 minutes). What else can we figure out about it?
First off, the fusion reaction used needs to aneutronic, or nearly so, since he doesn't seem to have any worries about dying of radiation poisoning within a couple days, and there's not nearly enough room in the device for neutron shielding. Any reaction with hard gammas as a major product is probably also out, unless he's also invented perfect shielding/photovoltaic tech for capturing electromagnetic waves of arbitrarily high energy levels. That basically leaves charged particles (protons or electrons, conceivably positrons) with high energies that can be captured and have their energy extracted directly to electricity, rather than running a heat engine. This is probably desirable for other reasons we'll see below.
Obviously the electrical power output can either be dialed up or down, or stored somehow until needed - he doesn't need anything like a gigawatt for the electromagnet used to keep shrapnel out of his heart, in fact the stuff would be ripped right out of him with probably lethal results.
The arc reactor got to be ridiculously efficient, both in production of energy and extraction of energy for electrical current, since he doesn't get fried by waste heat every time he dials up the power output. Maybe the armor has some kind of cooling mechanisms, but that wouldn't help too much with the issue that the generator is embedded right in his chest. All that power gets extracted through a really small electrical cable, although maybe that's just the lead to the electromagnet - but even so, the available surface for the sides of the reactor to interface with his armor's electrical power systems isn't that much greater. So, again that suggests some kind of reaction that results in high energy charged particles that get captured for electrical power - less opportunity for waste heat. However, in order for the waste heat to be effectively nil, he's pretty much got to have room temperature superconductors, so that the thing doesn't melt just from electrical resistance in its wiring.
If we assume that he's got superconduction nailed already (and uses it in his missiles, since otherwise he wouldn't have the right stuff to scavenge), that actually explains a lot. However much energy the arc reactor can put out, he can use for his armor's systems without fear of overheating, at least depending on *how* it gets used. He might even be able to store energy that he's not ready to use yet in arbitrarily large quantities inside a superconducting loop, as an alternative to any type of conventional battery technology. It might even help explain how he gets a fusion reaction going in the first place.
First off, with superconducting cables, he can probably throw a *lot* of current into that palladium ring. Since palladium is not itself a superconductor, there's resistance, which means high voltage. High voltage translates into high energies for electrons, and possibly for other particles, which could potentially translate into the ability to overcome the Coulumb barrier to a fusion reaction, regardless of how high the temperatures would have to be to make this work in a more conventional reactor. It sounds more and more like the arc reactor works on the basis of accelerating hydrogen ions or something similar to fuse inside the palladium ring, spitting out even more energetic, heavier ions.
Second, being able to produce a room temperature superconductor suggests a lot more understanding of the nature of conductive metals with various dopants than we currently have in the real world. There might be some trick involving quantum tunneling or something similar, where the usual charge barrier to achieve an exothermic fusion reaction doesn't actually have to be breached, but can be sidestepped. In fact, the point where his superconducting cable actually meets up with the regularly conducting palladium ring might be key here.
Another thought - the blue glow constantly emitting from the arc reactor may also be telling. It looks a whole lot like Cerenkov radiation, which is what you get when a charged particle passes through an insulator at a speed greater than the speed of light through that medium. This usually happens when the particle(s) pass from an area where the speed of light through the medium (not to be confused with the speed of light in a vacuum, which is invariant) is relatively high, into a medium where it is relatively low (which would be due to various types of interactions with the atoms and electrons in the medium). So, the blue glow could be happening when electrons (which could presumably be circulating at or near the speed of light in a superconductor) get introduced to the central power core, or alternatively when protons or ions exit the fusion reaction at high speeds and then get slowed down as they interact with the outer parts and get captured for power extraction. Either way, it's a neat thought experiment.
That just leaves the limited lifespan of the device at peak power output. This can't simply be a matter of running out of hydrogen or other fuel to power the fusion reaction, since such fuel could surely be replenished - although that might require completely powering the device down, infusing it with hydrogen ions, and then starting it up again, which one imagines could be a finicky process (note that even the one Stark plans to be decommissioned is left running the whole time it functions only as a display item). Okay, maybe that 15 minute lifespan is just without refueling. On the other hand, perhaps running the thing at peak power actually degrades the device in some measurable way -whether that's gradually knocking the palladium atoms out of alignment, breaking down the superconductors, filling up voids with the wrong types of ions or charged particles (there might be a problem with positrons being one of the reaction products, for example - an opportunity for Stark to invent positronic circuitry next), or what have you.
Of course, even if the arc reactor is forever limited to providing 12 gigawatts of power (the second model is supposedly about four times as powerful) for no more than 15 minutes or so (although one gets the sense the new model has a longer factory warranty too), that's still a good 3 gigawatt-hours of lifetime energy production for a device the size of a hamburger, one which Stark was able to put together from scraps as Uncle Obadiah said. The use of palladium is not a major constraint on manufacture, since it uses only a few grams and current prices are in the $500 per ounce range. Perhaps the other components are more expensive. After all, superconducting cables designed for use in multimillion dollar 'repulsor' missile systems might even run you a million or two in manufacturing costs themselves. Even so, 3 gigawatt-hours is equal to 3 million kilowatt-hours, for which the current average price in the US is about $0.10, so the cost per unit (even once mass production is in place) would have to be higher than $300k in order for it *not* to make sense for Stark Industries to enter the power industry. Now, that would be a different way to save the world.
Anyway, I've been Googling commentary on the Iron Man movie, specifically the major technological MacGuffin - the arc reactor. And nobody seems to have put as much thought into it as me. Maybe that should tell me something...
All the rest of the Iron Man technology - boot jets, repulsor beams, everything - hinges on the energy output of Tony Stark's miniaturized arc reactor. The prototype built in the cave is quoted as putting out '3 gigajoules per second', otherwise known as 3 gigawatts, of power - but it's then immediately made clear that that's a peak output for a limited time only, since he says it can power something big for '15 minutes'.
The device is small, so it basically needs to be some type of nuclear energy or something even more exotic, such as matter-energy conversion or zero-point energy. The original, mammoth arc reactor back at Stark Industries looks like some kind of glass-walled tokamak, which points us towards fusion, and the central ring of the miniature version is made of palladium, clearly meant to imply a connection of some kind with the Pons/Fleischmann cold fusion fiasco. So, say it's some type of nuclear fusion - that would produce the required amount of energy while only 'burning' milligrams of hydrogen (which could be extracted from water vapor in the atmosphere, or from a tiny reservoir of water not shown, or infused in the palladium core - palladium is also being looked at for hydrogen storage, although I'm not sure 2 grams of the stuff could hold enough hydrogen to do 3 gigawatts for 15 minutes). What else can we figure out about it?
First off, the fusion reaction used needs to aneutronic, or nearly so, since he doesn't seem to have any worries about dying of radiation poisoning within a couple days, and there's not nearly enough room in the device for neutron shielding. Any reaction with hard gammas as a major product is probably also out, unless he's also invented perfect shielding/photovoltaic tech for capturing electromagnetic waves of arbitrarily high energy levels. That basically leaves charged particles (protons or electrons, conceivably positrons) with high energies that can be captured and have their energy extracted directly to electricity, rather than running a heat engine. This is probably desirable for other reasons we'll see below.
Obviously the electrical power output can either be dialed up or down, or stored somehow until needed - he doesn't need anything like a gigawatt for the electromagnet used to keep shrapnel out of his heart, in fact the stuff would be ripped right out of him with probably lethal results.
The arc reactor got to be ridiculously efficient, both in production of energy and extraction of energy for electrical current, since he doesn't get fried by waste heat every time he dials up the power output. Maybe the armor has some kind of cooling mechanisms, but that wouldn't help too much with the issue that the generator is embedded right in his chest. All that power gets extracted through a really small electrical cable, although maybe that's just the lead to the electromagnet - but even so, the available surface for the sides of the reactor to interface with his armor's electrical power systems isn't that much greater. So, again that suggests some kind of reaction that results in high energy charged particles that get captured for electrical power - less opportunity for waste heat. However, in order for the waste heat to be effectively nil, he's pretty much got to have room temperature superconductors, so that the thing doesn't melt just from electrical resistance in its wiring.
If we assume that he's got superconduction nailed already (and uses it in his missiles, since otherwise he wouldn't have the right stuff to scavenge), that actually explains a lot. However much energy the arc reactor can put out, he can use for his armor's systems without fear of overheating, at least depending on *how* it gets used. He might even be able to store energy that he's not ready to use yet in arbitrarily large quantities inside a superconducting loop, as an alternative to any type of conventional battery technology. It might even help explain how he gets a fusion reaction going in the first place.
First off, with superconducting cables, he can probably throw a *lot* of current into that palladium ring. Since palladium is not itself a superconductor, there's resistance, which means high voltage. High voltage translates into high energies for electrons, and possibly for other particles, which could potentially translate into the ability to overcome the Coulumb barrier to a fusion reaction, regardless of how high the temperatures would have to be to make this work in a more conventional reactor. It sounds more and more like the arc reactor works on the basis of accelerating hydrogen ions or something similar to fuse inside the palladium ring, spitting out even more energetic, heavier ions.
Second, being able to produce a room temperature superconductor suggests a lot more understanding of the nature of conductive metals with various dopants than we currently have in the real world. There might be some trick involving quantum tunneling or something similar, where the usual charge barrier to achieve an exothermic fusion reaction doesn't actually have to be breached, but can be sidestepped. In fact, the point where his superconducting cable actually meets up with the regularly conducting palladium ring might be key here.
Another thought - the blue glow constantly emitting from the arc reactor may also be telling. It looks a whole lot like Cerenkov radiation, which is what you get when a charged particle passes through an insulator at a speed greater than the speed of light through that medium. This usually happens when the particle(s) pass from an area where the speed of light through the medium (not to be confused with the speed of light in a vacuum, which is invariant) is relatively high, into a medium where it is relatively low (which would be due to various types of interactions with the atoms and electrons in the medium). So, the blue glow could be happening when electrons (which could presumably be circulating at or near the speed of light in a superconductor) get introduced to the central power core, or alternatively when protons or ions exit the fusion reaction at high speeds and then get slowed down as they interact with the outer parts and get captured for power extraction. Either way, it's a neat thought experiment.
That just leaves the limited lifespan of the device at peak power output. This can't simply be a matter of running out of hydrogen or other fuel to power the fusion reaction, since such fuel could surely be replenished - although that might require completely powering the device down, infusing it with hydrogen ions, and then starting it up again, which one imagines could be a finicky process (note that even the one Stark plans to be decommissioned is left running the whole time it functions only as a display item). Okay, maybe that 15 minute lifespan is just without refueling. On the other hand, perhaps running the thing at peak power actually degrades the device in some measurable way -whether that's gradually knocking the palladium atoms out of alignment, breaking down the superconductors, filling up voids with the wrong types of ions or charged particles (there might be a problem with positrons being one of the reaction products, for example - an opportunity for Stark to invent positronic circuitry next), or what have you.
Of course, even if the arc reactor is forever limited to providing 12 gigawatts of power (the second model is supposedly about four times as powerful) for no more than 15 minutes or so (although one gets the sense the new model has a longer factory warranty too), that's still a good 3 gigawatt-hours of lifetime energy production for a device the size of a hamburger, one which Stark was able to put together from scraps as Uncle Obadiah said. The use of palladium is not a major constraint on manufacture, since it uses only a few grams and current prices are in the $500 per ounce range. Perhaps the other components are more expensive. After all, superconducting cables designed for use in multimillion dollar 'repulsor' missile systems might even run you a million or two in manufacturing costs themselves. Even so, 3 gigawatt-hours is equal to 3 million kilowatt-hours, for which the current average price in the US is about $0.10, so the cost per unit (even once mass production is in place) would have to be higher than $300k in order for it *not* to make sense for Stark Industries to enter the power industry. Now, that would be a different way to save the world.