When the article contains utter nonsense like "In Chapman’s aneutronic fusion reactor scheme, a commercially available benchtop laser starts the reaction. A beam with energy on the order of 2 x 10'18 (couldn't figure out how to type the exponent right) watts per square centimeter" and then estimates ten years till we have engines going to Mars, I pretty much give up on it. I was just at Radio Shack today, and I'm pretty sure I didn't see any "commercially available" two quintillion watt lasers for sale.
Oh, and Radio Shack still exists? I though they went out of business years ago...
Come on guys, Radio Shack still sells parts for the hobbyist in some of their stores and most definetly from their web site, See: http://www.radioshack.com/category/index.jsp?categoryId=2032058 That said, buying your parts from Allied, Digikey, Mouser and/or Newark mail order might just make more sense depending on what you are in need of.Best,
Quote from: Nomadd on 06/29/2011 12:45 am When the article contains utter nonsense like "In Chapman’s aneutronic fusion reactor scheme, a commercially available benchtop laser starts the reaction. A beam with energy on the order of 2 x 10'18 (couldn't figure out how to type the exponent right) watts per square centimeter" and then estimates ten years till we have engines going to Mars, I pretty much give up on it. I was just at Radio Shack today, and I'm pretty sure I didn't see any "commercially available" two quintillion watt lasers for sale. They're pulsing the laser at that power for a very short amount of time. Thats easy to do.
Note that they didn't actually say what the thrust is, just that 100,000 particles per pulse were accelerated. Considering that low thrust is generally associated with high ISP systems, the omission of a comparable thrust metric is suspicious.
How is that different from other laser-based fusion propulsion schemes?
Does it promise to produce net power?
QuoteDoes it promise to produce net power?No. The purpose is rocket propulsion, not power. Some of the excess alphas can be captured and converted to electricity to increase the system efficiency, but net gain is not the goal.
Seems to me that the ideal fusion rocket would use (straight) hydrogen as fuel, so that you could, in theory, refuel at the target planet and/or solar system!! --Brian
There's a spaceship with a very high specific power method of harnessing net-power fusion for propulsion right now orbiting a dwarf planet (arguably). Anyone have a guess of what I'm talking about?
Produce net power from fusion (i.e. power the fusion plant with just its own power, plus light a light bulb) and then we can talk about a fusion thruster being available in "just 10 years."I don't think net-power fusion is impossible (and actually, something like laser-induced inertial-confinement fusion seems like the most promising approach to me right now), but until it's demonstrated (won't even ask about the economics), talking about a fusion thruster in the short-term is ridiculous.There's a spaceship with a very high specific power method of harnessing net-power fusion for propulsion right now orbiting a dwarf planet (arguably). Anyone have a guess of what I'm talking about?
Quote from: Robotbeat on 01/05/2012 04:47 pmProduce net power from fusion (i.e. power the fusion plant with just its own power, plus light a light bulb) and then we can talk about a fusion thruster being available in "just 10 years."I don't think net-power fusion is impossible (and actually, something like laser-induced inertial-confinement fusion seems like the most promising approach to me right now), but until it's demonstrated (won't even ask about the economics), talking about a fusion thruster in the short-term is ridiculous.There's a spaceship with a very high specific power method of harnessing net-power fusion for propulsion right now orbiting a dwarf planet (arguably). Anyone have a guess of what I'm talking about?Net power production from the fusion reaction is not required if you want to use a fusion thruster.You could power the fusion reaction using an external power source (nuclear or solar) and simply use the fusion reaction to produce directed thrust with a very high exhaust velocity, much higher than with conventional electric thrusters. This is what this fusion thruster is about. It isn't about sustaining the fusion reaction on its own energy.
I suppose, thinking about it, there is no reason why fast moving charged particles could not be efficiently converted to electrical power.
Quote from: KelvinZero on 01/06/2012 03:41 amI suppose, thinking about it, there is no reason why fast moving charged particles could not be efficiently converted to electrical power.What about passing the charged particles through spirals of wire?
Quote from: scienceguy on 01/06/2012 04:10 amQuote from: KelvinZero on 01/06/2012 03:41 amI suppose, thinking about it, there is no reason why fast moving charged particles could not be efficiently converted to electrical power.What about passing the charged particles through spirals of wire?That's what the Focus Fusion guys are trying to do. Their basic idea is to create instabilities in B11-H plasma, that generates He nucleus. Since those are ions, they pass them through a coil and generate electricity directly. I don't think they are getting net energy. But apparently they've made a very nice source of X-Rays.