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ESA Moves Forward on New Electric Engine
museumpeace writes to tell us the ESA is reporting that they have confirmed the principle behind a new space thruster. Plasma Double Layers, first discovered by Australian researchers Christine Charles and Rod Boswell, may help to develop a new electric engine that gives more thrust than traditional engines while still maintaining efficiency. From the article: "In essence, a plasma double layer is the electrostatic equivalent of a waterfall. Just as water molecules pick up energy as they fall between the two different heights, so electrically charged particles pick up energy as they travel through the layers of different electrical properties."
In essence, a plasma double layer is the electrostatic equivalent of a waterfall. Just as water molecules pick up energy as they fall between the two different heights...
Water molecules do not pick up energy as they fall. There potential energy is simply converted into kinetic energy. However, they had the energy all along in the form of potential energy.
Somehow I doubt this engine will get anything into orbit. I believe the electrical engine in the SMART-1 mission referred to provides a thrust that is equal to the weight of a piece of a4 paper. So delivering many times more thrust would probably add up to a whole stack of paper.
These engines are usuful in space, though. Probes don't have to bring any fuel, just solar panels.
Also, an engine can not make something go faster than the speed at which it spews out stuff. The charged particles from on electrical engine are much faster than anything that comes out the back of a rocket, enabling much higher speeds.
There not really "Electric Engine"s either are they?
Calling them Electric Engines would mean calling pretty much every engine around an electric engine.
Plasma or Ion engine's would be more descriptive in my opinion.
LOL! Mod +5 Funny! Slashdotter with a girlfriend! That's rich!!
I would hesitate to call this a "very low thrust" engine, since 100kw is somewhere around 140 horsepower. It may not be enough to escape earth's gravity (if not, maybe the mars or the moon?), but I wouldn't discount the possibility immediately without more information (like what do these thrusters weigh, and how much propellant do they need to carry).
The hardest part would be providing a 100kw power source, but this is the same problem as supplying power to the space elevator climbers, and it might be solvable with wireless power transmission (big lasers and solar panels).
Plasma needs to come from somewhere. Even if you have some renewable energy source like a solar panel, eventually you will run out of ions to exhaust.
Exhaust velocity doesn't impose a maximum velocity. Get on a train, stand on a skateboard, throw a basketball and see if you roll in the opposite direction a bit. Even if the train is going faster then you threw the basketball.
The reason you want an exhaust velocity as fast as possible is that the momentum your ship gains is equal in magnitude (and opposite in direction) to the momentum of your exhaust. Momentum is mass times velocity. Mass is kind of a pain, because you have to accelerate it, so you want to use as little of that as possible. So everything else being equal, the most efficient rocket will be the one with the fastest exhaust velocity.
Just as water molecules pick up energy as they fall between the two different heights,
They are not picking up anything, they are just transforming potential into kinetic energy.
Life is just nature's way of keeping meat fresh.
For a serious peek at the role of plasma dynamics in the solar system, you need go no farther than NASA: 15.1.1. Applicability of Hydromagnetics and Plasma Physics . For wider application, the Los Alamos National Laboratory has up a nice tour of The Universe (which universe even your neighborhood astronomer, if pressed, will admit is over 99% plasma-phase -- at least the baryonic bits! -- even if he has little inkling what that means), and links to refereed-journal papers.
I'm afraid ceoyoyo and 2008 will need to find their cranks elsewhere. That said, the Velikovskyite cultists at Thunderbolts have a very nice picture-of-the-day archive, with captions that besides being much more fun than the pap on APOD, are remarkably often thought-provoking. You don't have to believe that Venus popped out of Saturn in immediate prehistory (as "proven" by widespread legends) to enjoy them rattling the chains that hold astronomers in their 19th-century Christian-esque universe.
You can't honestly poke fun at a hairy-eyed Velikovskyite without ribbing the Big-bang mooncalves equally. The latter have much less excuse for their silliness, and a lot more to answer for.