New type of accelerator

GCNRevenger · 2004-11-10 15:52:53

That means your engine will produce very little thrust.

Don't forget to include the H2 bond disassociation and ionization energy when you calculate the energy required per kilo of fuel.

ERRORIST · 2004-11-10 16:09:07

With that exhaust velocity it would be far more thrust than todays ion engines. Correct?

GCNRevenger · 2004-11-10 16:58:04

Not really, even with relativistic effects, Xenon used in ion engines weighs 18 times as much.

ERRORIST · 2004-11-10 17:07:06

Even Xenon can be accelerated to .99%C in such an engine.

GCNRevenger · 2004-11-10 17:20:34

Yes it can, but the amount of energy required is far greater because of the increased mass of the Xenon.

Unless you use a bigger power source, the thrust of your engine that propells Xenon ions to 0.99C will be far far less, because you can't push as many ions to this speed with the same amount of energy, since they weigh so much more.

Its a no-win situation... oh, and if you are interested in numbers, Hydrogen requires 3060.4 kJ/mol to go from gas to a pair of H+ ions. The first ionization energy for Xenon is about 1170.4kJ/mol.

Euler · 2004-11-10 19:03:06

By rough calculation, that means you will use 7.467x10^(-4) kilograms of propellant per second. At 99%C the mass increase due to relativity is about 708%.

If my calculations are correct that would give about 1.7 million Newtons of thrust. Unfortunately, even at 100% efficiency, the power requirements would be above 500 terrawatts (the world's total energy consumption is around 1 terrawatt.)

GCNRevenger · 2004-11-10 19:33:01

I was mistaken, at 0.90C your mass would be 708%. At 0.99% your mass would be about 1,000%.

Now with reasonable efficencies Errorist, you are talking about an energy bill of 1,000 terrawatts for your relativistic proton engine. That would be a thousand thousand megawatts, a million times the power of the largest proposed space fission reactor, and ten million times the energy produced by the only space reactor in development.

I hope that you are seeing a little "problem" here. NASA has intentionally limited the fuel efficency of ion engines in order to produce useful thrusts with only a few thousand watts of power (and to cut down on engine weight, which would be extreme with a >0.90C accelerator).

GCNRevenger · 2004-11-10 19:44:30

The most powerful practical and advanced space reactor that I have heard contemplated, a very large Vapor Core nuclear reactor, would weigh in the neighborhood of a hundred tons or a bit more. It would produce about 250 megawatts.

So before you ask Errorist, no, you can't make that much energy even with a cluster of these reactors reactors.

More quick math: If you reduced the thrust down about 10,000 times, down to similar thrusts as the RL-10 rocket engine, then you would still need around a gigawatt of power.

Euler · 2004-11-10 20:30:58

Now with reasonable efficencies Errorist, you are talking about an energy bill of 1,000 terrawatts for your relativistic proton engine. That would be a thousand thousand megawatts, a million times the power of the largest proposed space fission reactor, and ten million times the energy produced by the only space reactor in development.

No, it goes kilo-mega-giga-terra-peta. 1,000 terrawatts is a billion megawatts. Or, brining the numbers down to a more easily comprehensible level, if the exhaust velocity is near c, then an efficient accelerator will require 300 megawatts per Newton.

GCNRevenger · 2004-11-10 20:44:08

Whoops your right, not that it really matters, since there is no way to produce that kind of energy

chat · 2004-11-10 21:52:24

GCNRevenger,

Just curious what you think the power requirements and thrust for my giant metal cd with atom vaporizer would be

Actually two wheels spinning in opposite directions will be needed for stability.

I get pretty low power requirements for both spinning and ark, and once spun up the wheels use very little power.

It seems to be a bit of a cheat on the power curves of conventional engines.

Max rpm for large wheels is the unknown though, and might be the downfall of the idea.

It is possible to play billiards with all atoms and energy,
A very inefficient game of pool though because most atoms are 99.9% nothing.

The real odds of electrons hitting ions are exceedingly poor, and of those collisions that happen useful ones are just about as unlikely.

Was trying not to be to negative.

John Creighton · 2004-11-10 22:04:54

It is possible to play billiards with all atoms and energy,
A very inefficient game of pool though because most atoms are 99.9% nothing.
The real odds of electrons hitting ions are exceedingly poor, and of those collisions that happen useful ones are just about as unlikely.

Another point is that as far as accelerating the space ship it doesn’t really matter if the electrons collide with the ions or not the acceleration of the space ship will still be the same.

ERRORIST · 2004-11-10 22:08:59

Photon traveling at C hits electron and electron accelerates to C instantly. Electron now traveling at C hits Ion traveling at 250,000 Mph from behind in a linear collision.Ion accelerates 1 meter pers second per linear collision.This is for a hydrogen ion.
Reaction force of the ion is much greater than the electron as it leaves the ship at any velocity.

GCNRevenger · 2004-11-10 22:16:12

Photon traveling at C hits electron and electron accelerates to C instantly. Electron now traveling at C hits Ion traveling at 250,000 Mph from behind in a linear collision.Ion accelerates 1 meter pers second per linear collision.This is for a hydrogen ion.

Um. What?

Errorist, you have been reading previous posts haven't you? You cannot use quantum electrodynamics to get around the law of the conservation of energy: in QED, the time that the electron is "traveling" at 1.00C is literally instantainous, that is, no time for it to hit any ions.

ERRORIST · 2004-11-10 22:36:33

That is if the ion is at rest. However, the ion is already moving on out at 250,000 mph out the backend of the ship during its acceleration phase.

GCNRevenger · 2004-11-10 22:47:24

No.

No
No
No

Again, you are trying to cheat the law of conservation of energy through trickery. It won't work. You can't get more energy out of a system then you put into it. Using relativly low energy from light photons to make gargantuan kenetic particle energies just won't work. You can't cheat thermodynamics. No matter what you do or scheme you dream up, you are inevitibly going to have some fatal flaw, because you can't get away from thermodynamics. It will always break whatever super-engine idea you come up with.

Unless you can make huge amounts of energy, then you can't make an engine with superhigh performance in both fuel efficency and thrust. Your 0.99C near-zero-fuel proton engine, if it requires 300MW per N of thrust, even if your engine is 100% efficent. A laser engine, if you could convert 10% of the laser light into particle momentum, you would need to generate 30,000MW for that one Newton of thrust with a 10% efficent laser...

One Newton by the way, is about 1/100,000th the thrust of a single RL-10 rocket engine.

ERRORIST · 2004-11-11 00:05:24

That energy is already there. How much energy does it take to move a photon at the speed of light? It is conserved in the photon.

GCNRevenger · 2004-11-11 06:03:12

NO, it is not. The energy has to come from somplace. That is the central and unavoidable truth of the conservation of energy, that you can't remove more energy from a system then you put in.

You also should not be thinking about using quantum electrodynamics as a particle booster. In QED, the "regular" rules of the universe don't apply at all. An electron can emmit an infinite number of "photons" that are only virtual photons and are not fully real. Plus, since the electron remains in its hyperaccelerated state for zero time, then there is zero chance that it will hit anything during this time. Its not just close to zero, it IS zero.

chat · 2004-11-11 14:22:49

John Creighton,

Yeah it a useless reaction for any space engine to play billiards.

If anyone uses electricity, i think charged plates or liner accelerators are the way to speed up the ions.

Now deep space with a small electrical powered linear accelerator for a second push, that is another story

chat · 2004-11-11 14:38:13

GCNRevenger ,

It's nice to see someone with the same grasp of things moving at C not experiencing time.

My personal beliefs are that C is the speed of time and not an arbitrary speed limit.

For light that works well, light will never interact with anything else since light has no mass and no time and no space.

But for electrons they do have mass at C yet they cant.
Or is the max speed for electrons 99.999999----C and the explanation of the mass is the close to C speed and not true mass.

Either way electrons do experience time, or Einstein was way off

GCNRevenger · 2004-11-11 15:10:13

Everything that is moving below the speed of light except light itself will behave by "normal" laws, but otherwise anything that isn't light (like electrons) traveling at 1.00C and not .999...C will not behave under normal laws. Time is one of those things that no longer applies persay, so you are correct Chat.

ERRORIST · 2004-11-11 20:17:09

How fast can a CRT accelerate electrons and then have the electrons collide with ions?
Also how much energy does it take to accelerate a photon to the speed of light?
http://static.howstuffworks.com/gif/ele … -gun-2.jpg

chat · 2004-11-12 06:02:37

ERRORIST,

I believe your talking about a cathode ray tube.
For those that didn't take abbreviations 101

The electrons in a cathode ray tube fire at near C.
A measurable push on the glass does exist in a TV, but it is very very small.

To use this sort of idea as an engine a number of problems exist.
It is a very inefficient exchange of power, it wont work without a gas medium for the electron to pass through.
And the push it exerts makes deep space look like a Ferrari.
It is also pushing in a closed environment so the laws of conservation of energy must also come into play.
Although the push it creates does have an amount of internal shock in a positive direction.

With a very large power source it is a feasible engine, but so is high speed ion drive at .90c using similar power and greater thrust.

GCNRevenger · 2004-11-12 07:01:54

How fast can a CRT accelerate electrons and then have the electrons collide with ions?
Also how much energy does it take to accelerate a photon to the speed of light?
http://static.howstuffworks.com/gif/ele … -gun-2.jpg

I don't know how much energy it actually takes to power a large thermoionic free electron generator and accelerate those ions, but you can calculate a minimum energy using the thermodynamic equations that are layed out on this thread.

A photon doesn't accelerate, from the first instant that it is released from electronic or nuclear decay, it is already traveling at the speed of light within its medium. There is no "acceleration," light is always traveling at the speed of light within its medium, it doesn't play by the rules of regular particles.

ERRORIST · 2004-11-13 04:56:16

I don't know how much energy it actually takes to power a large thermoionic free electron generator and accelerate those ions, but you can calculate a minimum energy using the thermodynamic equations that are layed out on this thread.

A photon doesn't accelerate, from the first instant that it is released from electronic or nuclear decay, it is already traveling at the speed of light within its medium. There is no "acceleration," light is always traveling at the speed of light within its medium, it doesn't play by the rules of regular particles.

How much energy does it take for a photon to achieve the speed of light?

New Mars Forums

Announcement

#76 2004-11-10 15:52:53

Re: New type of accelerator

#77 2004-11-10 16:09:07

Re: New type of accelerator

#78 2004-11-10 16:58:04

Re: New type of accelerator

#79 2004-11-10 17:07:06

Re: New type of accelerator

#80 2004-11-10 17:20:34

Re: New type of accelerator

#81 2004-11-10 19:03:06

Re: New type of accelerator

#82 2004-11-10 19:33:01

Re: New type of accelerator

#83 2004-11-10 19:44:30

Re: New type of accelerator

#84 2004-11-10 20:30:58

Re: New type of accelerator

#85 2004-11-10 20:44:08

Re: New type of accelerator

#86 2004-11-10 21:52:24

Re: New type of accelerator

#87 2004-11-10 22:04:54

Re: New type of accelerator

#88 2004-11-10 22:08:59

Re: New type of accelerator

#89 2004-11-10 22:16:12

Re: New type of accelerator

#90 2004-11-10 22:36:33

Re: New type of accelerator

#91 2004-11-10 22:47:24

Re: New type of accelerator

#92 2004-11-11 00:05:24

Re: New type of accelerator

#93 2004-11-11 06:03:12

Re: New type of accelerator

#94 2004-11-11 14:22:49

Re: New type of accelerator

#95 2004-11-11 14:38:13

Re: New type of accelerator

#96 2004-11-11 15:10:13

Re: New type of accelerator

#97 2004-11-11 20:17:09

Re: New type of accelerator

#98 2004-11-12 06:02:37

Re: New type of accelerator

#99 2004-11-12 07:01:54

Re: New type of accelerator

#100 2004-11-13 04:56:16

Re: New type of accelerator

Board footer