New type of accelerator

Euler · 2004-11-06 18:06:30

Of course if the electrons are moving at relativistic speeds they will have a much greater momentum and this will accelerate the positive ions.

The problem with accelerating particles to reletivistic velocities is that while momentum only increases lineraly with velocity(at least until the reletivistic effects become noticable), the ammount of energy required increases quadratically with velocity. If you try and use particles with higher velocities, you will need much more power to produce the same amount of thrust.

Since electrons are simple to accelerate to near C, i think the best way to accelerate ions is to have an acceleration coil with ions inside it.
Use the electron beam to accelerate the ions, then expel the ions at peek speed.

Using charged plates is simple and >99.5% efficient in practice. Trying to accelerate ions with electrons is both unnecessary and inefficient.

Deep space is a one push engine, with a liner accelerator and no rush to push the ions i believe ion speeds of .50c are possible.

Again, you don't want ion speeds that high because that would take to much power. Current ion engines operate near the ideal velocity given the power sources available to them. .5c is much faster than you would want the ions to go for any power source short of an advanced anti-mater reactor.

Hmmm…I think this post is dabbling beyond my level of physics.

I think that your toroid-stack must obey conservation of energy. It should take the electron as much energy to get to the point of maximum potential energy as it will gain when it leaves that point, so there should be 0 net change in the speed of the electron.

chat · 2004-11-07 04:37:46

Euler,

That is the same brick wall that i encounter with the idea.
The reactor has to be pretty hefty to make this type of ion acceleration feasible.

And where would you go with such a craft that takes 15 years to get to its final speed of around .21c, and still takes another 28 years to get to the alpha C slowdown point, plus 15 years to slow down.

Down sizing the reactor only down sizes the %c thrust.
A good point it is that down sizing the reactor doesn't down size the thrust output, only the velocity of the thrust.

A 50 chamber beast accelerating ions to .01 c will have decent velocities, decent acceleration, and little waste of power.

Just imagine building 50 individual chamber accelerators with a timed escape point for each one, you might want to have Scotty on board all the time, and Donald Trump and friends with funding

chat · 2004-11-07 05:05:38

John Creighton,

If you can em part the 50% of energy left over to a new stream it will work.

You will have to eject one ion and insert 1 new ion at the exact same time before the electron beam bounces back or breaks down.

With the timing being so finite i doubt if any time piece or computer would be up for the task, let alone the insertion and ejection of the ions.

With a mile long accelerator you would have less than 186,000 th of a second to accomplish the change.

ERRORIST · 2004-11-08 18:14:05

Photon traveling at C -------> hits electron. Electron accelerates to C instantly.ELECTRON hits Ion. Ion accelerates. If collisions are linear then acceleration is added to spacecraft.
Thus: Linear Photon-----> Electron----->Ion----->= acceleration

GCNRevenger · 2004-11-08 22:06:49

Errorist, you are still stuck with thinking in billiard-ball/solid-sphere subatomic physics. This is not productive, because your thinking is based on a concept which is simply not true. Photons do not "hit" electrons, there is no collision. Likewise with electrons, there is not a "collision" with the ion persay. The ions will absorb or scatter the electrons, nor do photons accelerate electrons efficently. Your entire way of thinking is built upon an over-simplified model of the subatomic realm, the simple rules of the "big" world simply do not apply to subatomic particles... Using a laser-pumped electron accelerator to increase the exhaust velocity of an ion engine is a terrible idea.

Another thing you seem to be desperatly trying to avoid is having to deal with thermodynamics. The idea that you can, through some trickery by stacking up conversion steps, get around inefficencies or come up with a super-engine that (nearly?) violates conservation of energy. You are thinking about this from the wrong direction anyway, since our ion or plasma engines are already very good and are quite efficent, and fiddling with tricks to try and boost their already high efficency would yeild only a very small benefit. Instead, you should be looking at it from the other end, how to make more energy, and then worry about how you will make it push the rocket.

ERRORIST · 2004-11-08 23:40:49

How would this accelerate Ions during the acceleration phase of the Typical Ion engine?

http://chronicle.uchicago.edu/010712/ar … aser.shtml

chat · 2004-11-09 05:51:15

ERRORIST,

I don't think an efficient way of colliding electrons to another atom will work.

A few atoms of electrons will effect the ions, but in most part they wont collide head on, and most wont collide.

Using electricity to speed up ions in other ways is better.

Electrons used to change magnets that speed up ions is a good way.

Also why stop at the tiny mass of ions, if you make a dynamo with a steadily enlarging coil inside it and add iron atoms to the center.
Spin the 500ft dynamo at very high rpm with electricity, then allow only the highest speed atoms to escape at the point of highest thrust at the outer rim.

Think of a 500ft cd ROM with atoms moving slowly towards the outside then escaping from only one edge and only one place per revolution.

This is a direct electron to any atom engine, and a simple machine.

GCNRevenger · 2004-11-09 06:34:19

Chat:

Sounds like a type of cyclotron to me, a primitive but relativly compact particle acclerator. While this will produce thrust, and will have very high exhaust velocity, it isn't terribly efficent nor can it be rigged to make signifigant thrust. You see, thrust and fuel efficency for a given amount of energy are inversely proportional, if you increase the velocity (and hence fuel efficency) you will automatically decrease thrust. Alot.

An ion engine is a very simple electrostatic linear accelerator, which uses the attractive/repulsive force of a strong electrical charge to pull/push ions out the engines, and it can do this to alot of ions, hence giving reasonable thrusts. Overall very efficent... a type of ion engine that uses magnets to enhance thrust (at the cost of some fuel efficency) is called a Hall Effect thruster, you might want to look that up.

Errorist:

That is a free-electron laser, it has nothing to do with propulsion, its just a really really big (an not too efficent) laser.

ERRORIST · 2004-11-09 09:37:55

Can you use a free electron laser to slam the electrons into ions so that they will accelerate to C?

GCNRevenger · 2004-11-09 09:54:55

The FEL doesn't move electrons at all directly, and cannot be used to move electrons efficently.

Even if it did, the electrons will not collide with the ions in the first place, and even if they did, the electrons have so little mass (tens of thousands of times less) compared to the ions, that they are worthless.

ERRORIST · 2004-11-09 10:44:40

Oh but they are moving so much faster than the Ion.

ERRORIST · 2004-11-09 10:49:40

Looks like they can collide.
http://www-phys.llnl.gov/N_Div/EBIT/e_i … Excitation

GCNRevenger · 2004-11-09 14:41:51

The electrons can be made to move much faster then the ions, BUT the electrons do not gain momentum any more efficently then the ions. Let me say that again for emphasis: electrons cannot be moved with signifigantly higher efficency then ions. Got it?

And even though the electrons are moving much faster, they still are too light to use in an ion engine. It would be like shooting BB's at a battleship hoping to speed it up.

Actually no, those are "collisions" in name only. If you would have botherd to read the definitions and seek to understand them, you would have learned that these electrons are being absorbed. No billiard-ball collision, no hard spheres, no super engine.

You MUST address the thermodynamics of your engine(s) too, you really have to, it doesn't matter what you do if you can't do that.

ERRORIST · 2004-11-09 15:38:19

The electrons can be made to move much faster then the ions, BUT the electrons do not gain momentum any more efficently then the ions. Let me say that again for emphasis: electrons cannot be moved with signifigantly higher efficency then ions. Got it?

And even though the electrons are moving much faster, they still are too light to use in an ion engine. It would be like shooting BB's at a battleship hoping to speed it up.

Actually no, those are "collisions" in name only. If you would have botherd to read the definitions and seek to understand them, you would have learned that these electrons are being absorbed. No billiard-ball collision, no hard spheres, no super engine.

You MUST address the thermodynamics of your engine(s) too, you really have to, it doesn't matter what you do if you can't do that.

I bet a BB would destroy a battleship if it were traveling at the speed of light.Electrons are moved more efficiently than ions because they are less massive.Actually yes,The collisions are Kinetic. Got it? The engine can be cooled by the very fuel it uses.

GCNRevenger · 2004-11-09 18:02:08

Errorist, stop for a minute and try thinking about your engines rather then make us do it and disagree when you don't like the answer... Think thermodynamics for a minute, that today's ion engines in NASA labs are capable of converting >80-90% of input electricity into momentum. Plasma engines in mind may be capable of even higher efficencies and higher thrust settings.

Now, the best you can hope for any new super engine you come up with is to wring another few percentage points out of that little gap between ~80 and 100%. No matter what you do, this is as good as it could possibly get. The problem is not with how efficent the engine is Errorist, ion engines or VASIMR have very good efficency, the problem is making the energy in the first place, the source of energy.

You really really must internalize and accept that for a given amount of energy, reguardless of what engine you use, the fuel efficency and the thrust are inversely proportional. You know what that means, right? That for a given power source (say, a nuclear reactor) if you increase the fuel efficency (exhaust velocity) then the thrust will drop. This is not because of the engine, this is because of the limited energy to power it.

Got it? Am I getting through to you? That no matter what you do or what trick you pull or conversion step you add, that your engine cannot possibly be a big improvement over current or near future engines. Its a consequence of the conservation of energy, the cornerstone of physics, and not because of any lack of engineering.

And so, you cannot move electrons much more efficently then ions, since modern ion engines are already above 80% efficent, that 10-15% is all you could improve over. Yes you can make them go faster, but they weigh far far less so your thrust is far less, for a given amount of energy. The relationship isn't linearly inversely proportional either, particularly with relativity at high fractions of C where it would really be bad.

"Actually yes, the collisions are Kinetic." ...is simply not true. Read your own links, the collisions result in electron absortion, they do not bounce off nor transfer their momentum to the particles in question. Your link clearly states, that the colission results either in excitation or change in charge. It is NOT a billiard-ball collision, electrons do not behave as tiny marbles! Give it a rest!

ERRORIST · 2004-11-09 18:38:40

http://www-phys.llnl.gov/N_Div/EBIT/e_i … Excitation

ERRORIST · 2004-11-09 18:44:04

Electron Impact Excitation
When an electron impacts an ion, it can excite the electrons in that ion. The excited state thus formed can decay in a variety of ways.

We have measured the cross sections for this process in a variety of ions, from our very first publication on neonlike barium to recent measurements in a number of lithiumlike ions.

ERRORIST · 2004-11-09 18:46:40

Impact means collision?

ERRORIST · 2004-11-09 19:14:41

Looks like they collide to me. How about you?

http://www.mpi-hd.mpg.de/ato/jb00_html/ … ode13.html

GCNRevenger · 2004-11-09 19:36:09

Errorist, you are just Googling the abstracts of scientific papers without even understanding what they are doing.

ERRORIST · 2004-11-09 20:00:25

I ain't doing no Google searches. Besides, the papers say collisions and impacts.Collisions are impacts and they have kinetic energy as the papers also state.I bet it would work if they tried an experiment.

chat · 2004-11-10 06:45:11

GCNRevenger,

It is a similar idea to a cyclotron, a bit different in the way it feeds material and ejects material.

Got the idea one day from opening my cd ROM after it decided to explode a cd and dent the case inside.

I agree it will be an inefficient engine, but an engine that can take advantage of current tech and use any fuel.

With its good thrust and simple construction it might be a good candidate for manned trips around the solar system.

It will need a lot of fuel and quite a bit of power to spin the dynamos to high rpm though.
And a good computer to decide when to release the fuel.

If you can combine the ark jet with this idea i think its a winner.

No fuel is inserted into the dynamo, but the dynamo is now a solid metal wheel that has a fixed plasma ark jet at the thrust point.
Since the outer rim is already at max speed a jolt of power here will turn the wheel edge atoms into plasma, and the spin of the wheel em parts all the kinetic energy to those atoms.

The ark jet doesn't even have to be that efficient, just good enough to vaporize atoms.
Now no other fuel is needed other that the electrical power for the spin and the ark.

The Hall Effect Thruster looks interesting, have read a bit already on it, but will be sure to read more

Errorist,

Even if one in 10 electrons were to hit ions head on and em part all the kinetic energy, it is only the same force as moving one ion in 100 with an addition velocity of 50% the electron weight.
A little like a pin pong ball hitting a bowling ball.

The remaining 90% have no interaction or a negative one.

The real models are more like 1 in 1000 make a direct kinetic exchange.

GCNRevenger · 2004-11-10 06:54:41

If I have to tell you that excitation or induced ionization are NOT billiard-ball collisions, then you must not know that much about subatomic particle physics. The momentum of the electron is not transferred to the ion. NOT transferred. The energy of the electron is converted to excitation energy or simple electron capture. Electrons generally do not behave like subatomic marbles.

Even if they did, you couldn't even hit the ion stream with them efficently, nor could you simply throw more electrons at them, since that would ruin the delicate charge balence of the spacecraft. And finally, because you CAN'T accelerate electrons far more efficently then regular ion engines accelerate ions, you can't, it wouldn't help anyway even if you could.

MarsDog · 2004-11-10 09:08:50

The electrons could be accelerated to near light speed, increasing their mass;
The spacecraft would acquire a high positive charge.
Positive ions would be allowed to escape, from the tips of needles, adding to the thrust.

And you have Porcupine Drive.

ERRORIST · 2004-11-10 10:50:24

A Nano Tube crossection is just 2 to 3 atoms across. If the Nono Tube filement was .001 long and full of ions an electron would have to hit an ion once inside.

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#26 2004-11-06 18:06:30

Re: New type of accelerator

#27 2004-11-07 04:37:46

Re: New type of accelerator

#28 2004-11-07 05:05:38

Re: New type of accelerator

#29 2004-11-08 18:14:05

Re: New type of accelerator

#30 2004-11-08 22:06:49

Re: New type of accelerator

#31 2004-11-08 23:40:49

Re: New type of accelerator

#32 2004-11-09 05:51:15

Re: New type of accelerator

#33 2004-11-09 06:34:19

Re: New type of accelerator

#34 2004-11-09 09:37:55

Re: New type of accelerator

#35 2004-11-09 09:54:55

Re: New type of accelerator

#36 2004-11-09 10:44:40

Re: New type of accelerator

#37 2004-11-09 10:49:40

Re: New type of accelerator

#38 2004-11-09 14:41:51

Re: New type of accelerator

#39 2004-11-09 15:38:19

Re: New type of accelerator

#40 2004-11-09 18:02:08

Re: New type of accelerator

#41 2004-11-09 18:38:40

Re: New type of accelerator

#42 2004-11-09 18:44:04

Re: New type of accelerator

#43 2004-11-09 18:46:40

Re: New type of accelerator

#44 2004-11-09 19:14:41

Re: New type of accelerator

#45 2004-11-09 19:36:09

Re: New type of accelerator

#46 2004-11-09 20:00:25

Re: New type of accelerator

#47 2004-11-10 06:45:11

Re: New type of accelerator

#48 2004-11-10 06:54:41

Re: New type of accelerator

#49 2004-11-10 09:08:50

Re: New type of accelerator

#50 2004-11-10 10:50:24

Re: New type of accelerator

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