Electrical (No Ion) Engine

[Dr. Kerbal]

What I mean by that I mean a stinger using only electrons. But could you use electrons coming back to produce thrust? Things isn’t space just get faster so sling shot em then come back with much more force and walla! It works! Or will it need  a positively churched magnetic field to attract the electrons out of the probe? Please help me with this.

[mikegarrison]

7 minutes ago, Dr. Kerbal said:

What I mean by that I mean a stinger using only electrons. But could you use electrons coming back to produce thrust? Things isn’t space just get faster so sling shot em then come back with much more force and walla! It works! Or will it need  a positively churched magnetic field to attract the electrons out of the probe? Please help me with this.

I find this helps:

[Entropian]

11 hours ago, Dr. Kerbal said:

But could you use electrons coming back to produce thrust?

Nope.  The reason the electrons fly back is due to Coulomb's law, and so the electrons will also be pulling on you (Newton's laws), so no net thrust.  This is why people use ion engines - they provide actual thrust and they don't charge your spacecraft.

11 hours ago, Dr. Kerbal said:

Things isn’t space just get faster

Hopefully not.  There's just nothing to slow things down, not something speeding it up.

11 hours ago, Dr. Kerbal said:

Or will it need  a positively churched magnetic field to attract the electrons out of the probe?

Magnetic fields aren't charged, and even then, they depend on velocity to have any force.  Have you looked at the Lorentz force law?  LFL: F = qE + q(v x B)  (If you haven't done extra calculus or linear algebra, the x is a cross product)

Edited October 25, 2020 by Entropian
Speellingg

[Dr. Kerbal]

Oh. This mybe harder than I though...

[sevenperforce]

Also electrons are ions. 

[kerbiloid]

38 minutes ago, sevenperforce said:

Also electrons are ions. 

Of positronium, I guess

[NFUN]

I'm not sure I fully understand exactly what you're saying, but I think you may find this thread useful

Edited October 25, 2020 by NFUN

[Nuke]

ion drives actually have to have electron guns firing into the thrust plume to keep the ions from turning around and coming back. the positive ions will usually have an attraction to the only negatively charged thing in the area, the ship itself. this counters any thrust created. so the electron guns, spray out enough electrons so the ions can be neutralized and carry on. 

if you used electrons only as your thrust, your ship would eventually develop a strong positive charge and draw them back. if somhow you prevented this i dont think you would get any more than what you could get out of a photon drive (300MW/newton). 

Edited October 26, 2020 by Nuke

[Entropian]

14 hours ago, Nuke said:

electron guns

A little nitpicky, but they're actually called hollow cathodes.  Electron guns use field emission to generate high-voltage streams of electrons, but low current.   Hollow cathodes ionize a gas, like xenon or argon, to get way higher amperage.  Ion thrusters require multiple amps of current from the hollow cathodes, something an electron gun would never be able to provide.

[Dr. Kerbal]

I’m asking if it is possible to make thrust with only electrons. No ions. Batteries have electrons correct, use those electrons to produce thrust. Solar panels or nuclear generator provide electrons and done! 
or is that not possible.

[sevenperforce]

11 minutes ago, Dr. Kerbal said:

I’m asking if it is possible to make thrust with only electrons. No ions. Batteries have electrons correct, use those electrons to produce thrust.

Batteries do not "have" electrons. 

Electrons are in everything and around everything. Electric batteries are a way to use chemistry to push the electrons which already exist around in a circle with a certain amount of force, and that force can then be used to do things (like power a lightbulb).

An incandescent electric flashlight has a battery and a filament. The battery pushes electrons in a circle, through the filament, and the force of the battery pushing those electrons around in the circle is released as heat in the filament, which causes it to get hot and glow.

Batteries are not a bottle of compressed electrons.

11 minutes ago, Dr. Kerbal said:

Solar panels or nuclear generator provide electrons and done! 
or is that not possible.

Solar panels do not "get" electrons from the sun. Rather, solar panels already have electrons in them, and the impact of sunlight pushes those electrons around in a circle, which provides the aforementioned force.

You can build an electron gun to fire electrons, and firing those electrons can produce thrust, but you still need to get the electrons from somewhere.

 

[magnemoe]

2 hours ago, Entropian said:

A little nitpicky, but they're actually called hollow cathodes.  Electron guns use field emission to generate high-voltage streams of electrons, but low current.   Hollow cathodes ionize a gas, like xenon or argon, to get way higher amperage.  Ion thrusters require multiple amps of current from the hollow cathodes, something an electron gun would never be able to provide.

The electron gun is only there to get rid of the extra electrons,  no need to send them out fast, the ion engine itself want to get the ions up to high velocity 

[Entropian]

33 minutes ago, magnemoe said:

The electron gun is only there to get rid of the extra electrons,  no need to send them out fast, the ion engine itself want to get the ions up to high velocity 

Yep, exactly.

[radonek]

On 10/25/2020 at 4:07 PM, Dr. Kerbal said:

Oh. This mybe harder than I though...

Maybe there is a reason space agencies are not using this already? Anyway, I think you are looking for this.

[Nuke]

11 hours ago, Entropian said:

A little nitpicky, but they're actually called hollow cathodes.  Electron guns use field emission to generate high-voltage streams of electrons, but low current.   Hollow cathodes ionize a gas, like xenon or argon, to get way higher amperage.  Ion thrusters require multiple amps of current from the hollow cathodes, something an electron gun would never be able to provide.

ok thanks for the clarification.  i was mostly noting that most ion drives need something to neutralize the plasma otherwise it comes back.

[Entropian]

Yes, the exhaust definitely needs neutralization.  Otherwise all kinds of weird things happen to your ship and its exhaust.

[Dr. Kerbal]

I guess we could use photons for infinite propulsion’s but what if we use electrons. We spit out electrons into space like atoms. But they’ll come back due to - and +. So. What if we have a magnetic field or some force that attractions to outside of the engine. Or what is we used high and fast loser that shoot electrons super fast so fast the pat the electron can’t come back. Maybe we could use gamma rays or something,Ike that or maybe lasers. I’m not sure .

[Nuke]

2 hours ago, Dr. Kerbal said:

I guess we could use photons for infinite propulsion’s but what if we use electrons. We spit out electrons into space like atoms. But they’ll come back due to - and +. So. What if we have a magnetic field or some force that attractions to outside of the engine. Or what is we used high and fast loser that shoot electrons super fast so fast the pat the electron can’t come back. Maybe we could use gamma rays or something,Ike that or maybe lasers. I’m not sure .

if you start firing electrons out the tail pipe, your ship will develop a positive charge, and the electrons will come back. so you need to also fire something positive to neutralize them. you could fire protons, but then you have an ion drive. positrons might also work but now you are in antimatter drive territory. 

[Entropian]

15 hours ago, Dr. Kerbal said:

I guess we could use photons for infinite propulsion’s but what if we use electrons. We spit out electrons into space like atoms. But they’ll come back due to - and +. So. What if we have a magnetic field or some force that attractions to outside of the engine. Or what is we used high and fast loser that shoot electrons super fast so fast the pat the electron can’t come back. Maybe we could use gamma rays or something,Ike that or maybe lasers. I’m not sure .

The electrons always will come back.  Lasers eject photons, not electrons.  A static magnetic field can never change the speed of an object.  Please look at the links I put in here:

On 10/25/2020 at 10:12 AM, Entropian said:

Nope.  The reason the electrons fly back is due to Coulomb's law, and so the electrons will also be pulling on you (Newton's laws), so no net thrust.  This is why people use ion engines - they provide actual thrust and they don't charge your spacecraft.

Hopefully not.  There's just nothing to slow things down, not something speeding it up.

Magnetic fields aren't charged, and even then, they depend on velocity to have any force.  Have you looked at the Lorentz force law?  LFL: F = qE + q(v x B)  (If you haven't done extra calculus or linear algebra, the x is a cross product)

 

 

[Spica]

On 10/26/2020 at 9:24 PM, Dr. Kerbal said:

I guess we could use photons for infinite propulsion’s but what if we use electrons. We spit out electrons into space like atoms. But they’ll come back due to - and +. So. What if we have a magnetic field or some force that attractions to outside of the engine. Or what is we used high and fast loser that shoot electrons super fast so fast the pat the electron can’t come back. Maybe we could use gamma rays or something,Ike that or maybe lasers. I’m not sure .

Unfortunately photon thrusters are anything but infinite propulsion. If the energy to be used in powering your thruster is carried along with your ship, you will not be very impressed by its performance.

A 100% efficient photon rocket powered by uranium can reach no more than ~250 km/s under it's own power. That's plenty fast for getting around the solar system, but a terrible waste of the energy contained in the uranium.

If the rocket instead uses that energy stored in the uranium to accelerate exhaust you can go much, much faster.

If the same amount of energy that the photon rocket used was instead used to accelerate normal exhaust, your rocket can now reach more than 10,000 km/s under its own power. That amounts to a 40-fold increase in speed, all at no increase in the total amount of energy consumed.

Edited October 28, 2020 by Spica
clarity

[Dr. Kerbal]

Wow. This is more complex than I though.

[KerikBalm]

On 10/27/2020 at 6:18 AM, Nuke said:

if you start firing electrons out the tail pipe, your ship will develop a positive charge, and the electrons will come back. so you need to also fire something positive to neutralize them. you could fire protons, but then you have an ion drive. positrons might also work but now you are in antimatter drive territory. 

If you fire them back fast enough, just like with gravity, there will be an escape velocity and they wont come back. You will build up a massive positive charge on your ship though...

On 10/26/2020 at 5:08 PM, Dr. Kerbal said:

I’m asking if it is possible to make thrust with only electrons. No ions. Batteries have electrons correct, use those electrons to produce thrust. Solar panels or nuclear generator provide electrons and done! 
or is that not possible.

Yes it is possible to make thrust with electrons. Yes batteries have electrons, so does your finger. Solar panels do not produce electrons, rather they can move those electrons.

Batteries don't spit out electrons, they move them. 

Don't think of electricity as "electrons", think of it as a flow of electrons. Electrical generators are like pumps that move water. When the water isn't moving, it can't power a water mill. When it is moving, your water mill can spin.

[wumpus]

As far as I know,  at least one satellite performed a proof-of-concept maneuver with an all-electric motor.  The key is that it was orbiting a planet with a magnetic field (Earth) and that it effectively used that field to move around.  Such actions might be useful for stationkeeping, and possibly moving microsats.

[Nuke]

2 hours ago, KerikBalm said:

If you fire them back fast enough, just like with gravity, there will be an escape velocity and they wont come back. You will build up a massive positive charge on your ship though...

Yes it is possible to make thrust with electrons. Yes batteries have electrons, so does your finger. Solar panels do not produce electrons, rather they can move those electrons.

Batteries don't spit out electrons, they move them. 

Don't think of electricity as "electrons", think of it as a flow of electrons. Electrical generators are like pumps that move water. When the water isn't moving, it can't power a water mill. When it is moving, your water mill can spin.

keep in mind that electric fields are many orders of magnitude stronger than gravity. also keep in mind that an electron engine is going to have a very low acceleration. 

now it is possible to use an accelerator to put a lot of energy into electrons to increase their relativistic mass. im not sure how easy it would be for a  ship with a strong positive charge to slow its exhaust back down.  id need a particle physicist to figure that out. 

[sevenperforce]

4 hours ago, KerikBalm said:

If you fire them back fast enough, just like with gravity, there will be an escape velocity and they wont come back. You will build up a massive positive charge on your ship though...

The more charge you build up, the more energy it will take to fire them back fast enough.