How would an electric rocket engine work?
- Thread starter Thermistor
- Start date
What about just ejecting a nice high energy beam of electrons as per a CRT (tube) but with even higher energy.
ion drive works by ionizing teflon and other fuels, and shooting the ions out. The force is ~= to that of a sheet of paper landing on your hand. However, without drag, this force is a constant acceleration.
I agree, e=mc^2.. if you did convert electrons to mass. you would .. have enough power to move you to pretty much anywhere though..
Being able to convert between matter and energy at will would probably completely change the problem though. Think of the kinds of vehicles we could create if we could build the thing from the atoms up.
But yeah, for space vehicles, you've got two ways of moving... 1) shoot some mass in one direction so you move in the other, or 2) have something push you.
In my opinion, number 2 is the most interesting, though of course number 1 has had some improvements with ion drives and such. The idea of light sails is just too cool though.
What does an electron weigh?
Assume the destination is 1/4 AU away and weighs 10^30kg. If we were to create a powerful gravitic field, how much energy would be required to arrive in a reasonable amount of time?
Assume the destination is 1/4 AU away and weighs 10^30kg. If we were to create a powerful gravitic field, how much energy would be required to arrive in a reasonable amount of time?
DrPizza
Administrator Elite Member Goat Whisperer
I wouldn't say "no" mass, nor "no appreciable mass" Rest mass of an electron is 9.1 x 10^-31 Kg.
But, it's easy to get a whole hell of a lot of electrons.
Let's make the rocket a few miles long and use a linear particle accelerator to get those suckers moving at close to the speed of light! Each electron would then produce an impluse of mv = 9.1x10^-31*3.0*10^8 kgm/s =2.7x10^-22 Newton-seconds. Hmmm... it's gonna take a LOT of electrons to produce an appreciable amount of impulse.
However, 1 amp = 1 coulomb/second = 6.24*10^18 electrons per second... I have no idea how many electrons are moving in a particle accelerator at any one time (except that it's a LOT of focused packets - no idea how many electrons per packet though, and searches for more info were met with irritation on my wife's part (who is insisting I get back to work in the kitchen... remodeling...)
Cogman
Lifer
- Sep 19, 2000
- 10,284
- 138
- 106
correct me if im wrong, but Electrons are a part of the atom, and are matter, Wouldn't you be converting electrons in energy? But yah it would be nice to be able to convert matter into energy. But the Power company would not like it very much.... Anyways, energy into matter conversion in mind, would it be possible for a spaceship to absorb some of the naturally ocurring energy from space and convert it into usuable matter for propulsion? Or would the amount just be way too small to be practical:
MadRat
Lifer
- Oct 14, 1999
- 11,977
- 294
- 126
So if they used laser energy to slowly disentigrate a catayst material, would the atoms from the catalyst eject at a speed faster than an ion engine? Perhaps it would be possible to harness laser engines to reach higher speeds than they currently can with ionic rocket engines.
- Aug 22, 2001
- 31,909
- 32,147
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You mean you don't have a warp core/drive???? I can't be the only one in there....
jk
yeah, these guys are right... the only place you'll see it with pure electricity is star trek
Just as a footnote, the point of a warp drive was NOT propulsion. All it did was warp space. This is theoretically possible but one would have to have a source of propulsion as well to move through the warped space. Think of it as a wormhole, because in essence it's pretty close. Just sitting at the mouth of a wormhole isn't gonna do you any good. You need to travel through to move anywhere.
DrPizza
Administrator Elite Member Goat Whisperer
That is fairly interesting. I'd like to point out though: "Energy can be obtained from either sunlight or from a nuclear reactor. "
Since energy is conserved, at 100% efficiency, the increase in kinetic energy would equal the "captured" solar energy. I've never thought about how much energy is available per square meter off the planet, but off hand, it doesn't seem sufficient. Or think of it this way... should I power my next house with solar energy, or nuclear energy... solar... nuclear... (Too bad I couldn't have my own nuclear reactor
)
Since energy is conserved, at 100% efficiency, the increase in kinetic energy would equal the "captured" solar energy. I've never thought about how much energy is available per square meter off the planet, but off hand, it doesn't seem sufficient. Or think of it this way... should I power my next house with solar energy, or nuclear energy... solar... nuclear... (Too bad I couldn't have my own nuclear reactor
)
MadRat
Lifer
- Oct 14, 1999
- 11,977
- 294
- 126
No Nuke for you! You would be one of those guys to throw three bajillion lights up during the Christmas season and piss off all the neighbors. And when the neighbors find out you got a nuke running the house then they'll all run out and buy nukes, too. Pretty soon one of the neighbors pisses you off, and seeing that you've had your nuke longer your stockpile of fissionable material is larger and pretty soon you go off making little nuke bombs to throw at them before they throw them at you. Its all one big mess. So, no nuke for you. Solar! Yes, you need solar. We don't want no freaking nuclear winter in your neck of the woods. So do us all a favour and just stick with solar...
GREAT question !!!
A web-search using the terms "ion propulsion" will yield web pages describing functioning
prototypes. In other words, it's a done deal, the propulsion part.
Basic concept ... negatively charged particles in an electric field will experience
a force. In the diagram shown, the particles experience a force moving them
to the right.
The tube uses alternating bands of conductive materials to create the electric field.
<==
TUBEooo-oooooo+oooooo-oooooo+oooooo-oooooo+oooooo-oooooo+oooooo-
IONSSoooooo-oooooooooooooo-ooooooooooooo-ooooooooooooo-ooooooooo - - - - - ==>
TUBEooo-oooooo+oooooo-oooooo+oooooo-oooooo+oooooo-oooooo+oooooo-
<==
The tube - which is part of the object being propelled - experiences a force moving it
to the left.
Bingo. Propulsion.
Conservation of energy, conservation of momentum, help to determine the limitations
of this method of propulsion.
Somewhat similar, for example the 2 mile long linear accelerator at Stanford, the
particles "surf" on electromagnetic fields generated by klystrons, high-power microwave
devices.
Of course, the laboratory ion propulsion prototypes, and the particles at SLAC,
have earth-bound power sources. And a practically unlimited supply of ions,
positively or negatively charged.
So the propulsion system has 2 parts -- power source, and the ion propulsion device itself.
My 2 cents - why wait for the power source to be developed, before beginning the
serious design work on the propulsion device ?
If it takes 50 years to develop the power source, and 50 years to develop the
propulsion system, why not just develop the propulsion system now ? Why wait till
2054 to start work on the propulsion system ?
The power source(s) may - or may not - be developed. Good R & D involves calculated
risks anyway.
I just wish we could find something to motivate this kind of technology development
besides "killing people" (military purposes). But, when you study the history of
technology, the '60's "Space Race" etc., military purposes provided a lot of the
motivation. So be it.
Of course, who's going to ride the result ? Volunteer to never see their family again,
and risk a head on collision at 10,000 or 100,000 miles per hour with a piece of debris ?
Land on a rock, plant an American flag, then chomp down on that cyanide pill they
give all astronauts, when the food supply runs out ?
Oh well. At least you'd be able to check your email.
My background ... BS '79, a junior college near Palo Alto. Spent the last 8 years
working in R&D for TRW & Northrop Grumman, and various defense and other
electronics companies in Silicon Valley before that.
Mighty interesting stuff. I am grateful to the tax-payers for the opportunity to work
on a little slice of this kind of stuff. One of my co-workers used to refer to our little
campus as a "social welfare program for engineers". Keeps us off the streets.
Which is probably a good idea. I still haven't learned how to stop on roller-blades.
I don't have the security clearance at present to see "the Real Kahuna". My understanding
is that prototypes exist which make one of our current "little projects", the Joint Strike Fighter,
look like a rubber-band powered balsa airplane. But, no stewardesses. :-(
My final suggestion -- most of the people that I know that have succeeded in this field
of endeavour "just started." In other words, if you're interested, "just do it". And don't
get discouraged if you spend a few thousand $ for a pile of scrap. Yes, you might be
limited to balsa wood instead of beryllium - but who wants to breathe beryllium dust
anyway ?
The government just spend a few billion $ on another pile of scrap. I won't name the
program cause I don't want to get in trouble. But it kept us engineers busy and a lot
of what we learned will be applied on other programs.
As for the rest -- well, hey. Someone's got to keep the scrap dealers supplied with good junk.
As far as "most efficient" ? Shoot, give me $5 Million and 5 years and I'll have a better answer.
And probably come back asking for more money.
Roger
equity@tns.com
Actually, it's tns.net
gsellis
Diamond Member
- Dec 4, 2003
- 6,061
- 0
- 0
Give me enough wattage and we can built the mother of all railguns. With a material that will react to the magnets included, we could then make anything push us along, including dog poop. Dog poop leave at .1c has a nice equal and opposite reaction. Just don't want to be in the backwash.
I was hoping somebody would bring up dog-poop.
What does dog poop have to do with propulsion ?
Well, if you wanted to fling something out the back of a space-ship FAST , what material would you choose ?
Poop seems like a logical choice. Obviously ( is that obvious ? ) it needs to have a charge (electric or magnetic)
( though I guess "magnetic charge" is the wrong term ... dipole, whatever ) ( bear with me, we're talking about
dog-poop powered space-ships here )
Anyway, (doing my best Spock imitation ?), it does seem not only possible, but Logical.
You know, I was hoping someone would bring up UFO's
Why do I have to do all the work ? ;-)
If there's any single ladies out there, don't worry, I'll let you be on top.
ANYWAY, speaking PERFECTLY seriously here, if you read the published, sourced, authentic accounts of
"anomalous behavior" (I don't have a television, I've actually never watched the X-Files) (but I highly
recommend "Above Top Secret", by Timothy Goode, partially because it is based entirely on the
published, sourced, authentic accounts of uniformed service personnel) ...
What has been reported - in hundreds (thousands ?) of such incidents -
1. Electromagnetic interference (EMI). Lots of EMI. (You know, like that line in the first Matrix - "Guns ?
Lots of Guns ?" )
2. Proximity of anomolous aircraft to bodies of water.
3. Not just Electromagnetic transients. EMI signatures that indicate the presence of alternating fields
(the proverbial time-harmonic electromagnetic fields)
OK, so that describes the SIGNATURE (in simple physics terms) of the official record.
Here comes a logical explanation:
1. The anomolous craft load up on H2O
2. The H2O is broken down into OH- and H+ molecules. We call it hydrolysis.
3. In alternating fashion, these ions are propelled out of the ass end of the anomolous craft. Bingo. Propulsion.
4. What happens if the anomolous craft only fires negative molecules ? It develops a huge positive charge,
which is generally not a good idea, unless you're trying to generate lightning. Hence the need to shed
negative and positive charges in approximately equal amounts. Although I'm sure they have pretty
bodacious capacitors (for charge storage).
So, why is the "official" story that they're "still" engaged in the SETI ? (which implies "they" haven't
found any yet)
Because "they" want to break the news G R A D U A L L Y
because "they" are concerned that if the anomoulous craft land in front of the White House on the
evening news we (humans) will all go f*cking BERSERK (and the stock market might crash ?)
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Obviously, the anomalous craft have some pretty clever power sources.
"I'm a Christian
I'm a Republican
I interviewed with the CIA when I got out of college
and I belong to a UFO-abduction support group" <== some guy actually said this to me during a job interview.
Did I get the job ? I guess that depends on what the job is, eh ?
Now could someone please help me figure out my Serial Presence Detect issue on my ASUS P4C800E motherboard ?
Please ?
http://forums.anandtech.com/categories.cfm?catid=29
Thanks.
Roger
equity@tns.com
Actually, it's tns.net
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