Exploring Propulsion with Light & Magnetic Fields

[StoyanNikolov]

while browsing for new propulsion methods I found the following interesting:
https://en.wikipedia.org/wiki/Radiation_pressure

"Radiation pressure (also known as light pressure) is the mechanical pressure exerted upon any surface due to the exchange of momentum between the object and the electromagnetic field.
This includes the momentum of light or electromagnetic radiation of any wavelength that is absorbed, reflected, or otherwise emitted (e.g. black-body radiation) by matter on any scale (from macroscopic objects to dust particles to gas molecules)."

So my question is: If a solenoid and a metal plate are attached together and they replace the light with an electromagnetic field from a solenoid, is it possible to have net thrust as shown in picture below? (Eddy current Repulsion Magnetic field from Solenoid and Metal Plate):

Perhaps it is better to Consider 2 cases :
Case 1 : Source of Light and Reflector plate attached together . Will there be Net Unidirectional thrust ?
Case 2 : Source of Magnetic field or Antenna and Metal reflector plate attached together . Will there be Net Unidirectional thrust ?

 

[berkeman]

If you generate EM and direct it away from the craft (whether it bounces off the metal plate in the process or not), you effectively have a Photon Rocket:

https://en.wikipedia.org/wiki/Photon_rocket

If you generate an oscillating magnetic field that generates Eddy Currents in the plate, you are losing energy to heating the plate and the plate will do a poor job of reflecting that oscillating EM energy.

Note that in these schemes, the photons/EM have to leave the craft, so that momentum is conserved in providing propulsion to the craft. If you do all of this inside the craft and no photons/EM leave the craft, then by Conservation of Momentum there can be no net thrust. Discussions and debunking of such "Reactionless Drives" are not allowed at PF.

 

[jrmichler]

Your Case 1 describes a photon rocket. When you emit light, there is a reaction force. A mirror changes the direction of the force, but not the magnitude. We can do a simple calculation to find the usefulness of a photon rocket.

Sunlight at 1 AU has radiation pressure of 4.5 microNewtons per square meter, and a power of 1.3 kW per square meter. We need about 4.5 kW to generate that much light, so a photon rocket would get about 1 microNewton of thrust per kilowatt of power. Or 1 milliNewton per megawatt. Or 1 Newton per gigawatt.

A one gigawatt nuclear power plant takes up one square mile of land, and weighs many thousands (or more likely millions) of tons. All that to generate one newton of thrust, and explains why nobody has built a photon rocket.

I'm sure that a similar calculation applies to a directional radio beam, but will leave that for somebody that actually knows how to do the calculation.

 

[StoyanNikolov]

How about the configuration on the attached Picture.
Please consider Both Metal plates and Both Solenoids are attached together, so there is no possible movement between them.
They can move only as a whole/attached together.

The magnetic field from Current carrying Solenoids is Pulsating , but
The North poles of Both Solenoids are always Pointing toward Metal plates (Please consider them to be perfect conductor).

In this case the Pulsating magnetic field/EM field will be the "Propellant".

Will there be "upward" (On the attached picture) net thrust ?
Thank you.

 

[berkeman]

Thread is closed for Moderation...

 

[berkeman]

How about the configuration on the attached Picture.

Please stop trying to post about Reactionless Drive configurations. You know by now that the subject is considered a Forbidden Topic at PF. Please re-read Post #2 above.

This thread will remain closed. Have a nice day.