EM Drive Developments - related to space flight applications - Thread 8

[Bob012345]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

[WarpTech]

The TM modes seem to have the highest Q for this cavity. Does that make sense? The loop is having its field in the axial direction of the cavity.

Thanks,
Peter

That is because you're using side wall injection. You are going to have a very difficult time (just like NASA did) trying to excite the TE01x modes. For example, I was able to locate TE012 at ~4.407Ghz, but it is VERY weak with the antenna mounted to the side and is very close to a TM mode.

If you move the loop to the center things clear up greatly. Also, FEKO says your antenna wire diameter of 2mm is too much. The ratio of wire radius and length are not ideal. You may need to switch to a thinner wire.

Thanks a lot for the advice and the sim, Monomorphic. I will make a new cavity with 1 mm wire. But, uhh..., how about the supply wires if you move the loop to the center? In a sim it is easy to do, but you will have strong influence of the wires from the side or endplate (either coax or two copper wires).
How about placing the loop on one of the endplates, halfway the center and edge, and opening (B-field) facing the center? The loop is not placed at a maximum then, that's true. I will try it out.
Peter

What is the impulse response of your antenna? In other words, if you apply a very short current pulse (ns), what does the ringing feedback signal look like? Is it a nice uniform sine wave at the resonant frequency of the cavity, or is there harmonic distortion from overlapping modes?

Just curious. I was thinking about doing exactly what you have done, just to see what comes out and how I could design more powerful, ruggedized driving circuit to power it. I'm looking for oscillograms, before I start making some of my own.

[Peter Lauwer]

What is the impulse response of your antenna? In other words, if you apply a very short current pulse (ns), what does the ringing feedback signal look like? Is it a nice uniform sine wave at the resonant frequency of the cavity, or is there harmonic distortion from overlapping modes?

Just curious. I was thinking about doing exactly what you have done, just to see what comes out and how I could design more powerful, ruggedized driving circuit to power it. I'm looking for oscillograms, before I start making some of my own.

I have not performed such a measurement. I have to see whether I can get access to the necessary equipment for that. The measurement I have described was just reflection as a function of frequency with a network analyzer.

[zellerium]

My first test cavity (cylinder), measured with a network analyzer (Agilent E8364B). Length = 130 mm, r = 49 mm. Coupling loop, diameter 15 mm, at 1/4 of length (32.5 mm), 2 mm silvered copper wire.
Aim was to see what Q can be reached with untreated (unpolished) copper pipe and plates and this coupling (and to get some experience with copper soldering). And whether I can identify the modes (not yet).

In the picture 2-3 GHz, 6 peaks can be seen:
2.013 GHz   Q= low
2.136 GHz   Q=~600
2.358 GHz   Q=~23k
2.381 GHz   Q=low
2.642 GHz   Q= not calculated (order 100-1000)
2.917 GHz   Q= not calculated (order 100-1000)

Cheers,
Peter

I ran a quick HFSS eigenmode sim on it without the loop and the resonant frequency seems to correlate very well. I'm not sure what mode you had ~ 2GHz, the TE111 should be the first one. Maybe an effect of the antenna.

Hope this helps

Kurt

[edit: each field plot is normalized to the same scale]

Hi Kurt,

Can you please also run a simulation 3-4 GHz? It will be interesting to identify more modes. Is there a TE011?

3.249 GHz      TM012?   
3.381 GHz         
3.747 GHz      TM110?     Q=12k
3.938 GHz      TM111?     Q=20k

The TM modes seem to have the highest Q for this cavity. Does that make sense? The loop is having its field in the axial direction of the cavity.

Thanks,
Peter

Sure!
Here are the next four modes:
3.31E+09   3.78E+09   3.79E+09   3.91E+09

[OnlyMe]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

I was unable to open the PDF so I am unsure just what you were responding to. That said on the face of it your statement is false, because heat is a measure of the (more or less randomized) momentum of a group of involved atoms and molecules.

When dealing with everyday classical masses, velocities and impact reactions, the resulting change in temperature is often insignificant, that does not mean that it does not exist.

Heat itself is just a specialized term for a type of momentum.

When dealing with everyday objects and classical everyday velocities, most of the transfer of momentum is limited to a sum of the classical velocities of the after impact objects. As impact velocity increases so does the amount of the initial momentum that results in measurable "heat" and a comparable reduction in the resulting classical velocities.

[VIY]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

I was unable to open the PDF so I am unsure just what you were responding to. That said on the face of it your statement is false, because heat is a measure of the (more or less randomized) momentum of a group of involved atoms and molecules.

Wrong. Heat is a randomized motion  with an average momentum of zero. Heat does not carry, nor transfer momentum.

[dustinthewind]

The TM modes seem to have the highest Q for this cavity. Does that make sense? The loop is having its field in the axial direction of the cavity.

Thanks,
Peter

That is because you're using side wall injection. You are going to have a very difficult time (just like NASA did) trying to excite the TE01x modes. For example, I was able to locate TE012 at ~4.407Ghz, but it is VERY weak with the antenna mounted to the side and is very close to a TM mode.

If you move the loop to the center things clear up greatly. Also, FEKO says your antenna wire diameter of 2mm is too much. The ratio of wire radius and length are not ideal. You may need to switch to a thinner wire.

Thanks a lot for the advice and the sim, Monomorphic. I will make a new cavity with 1 mm wire. But, uhh..., how about the supply wires if you move the loop to the center? In a sim it is easy to do, but you will have strong influence of the wires from the side or endplate (either coax or two copper wires).
How about placing the loop on one of the endplates, halfway the center and edge, and opening (B-field) facing the center? The loop is not placed at a maximum then, that's true. I will try it out.
Peter

Added some sketch to the image.

[aero]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

I was unable to open the PDF so I am unsure just what you were responding to. That said on the face of it your statement is false, because heat is a measure of the (more or less randomized) momentum of a group of involved atoms and molecules.

Wrong. Heat is a randomized motion  with an average momentum of zero. Heat does not carry, nor transfer momentum.

It is quite easy to say "Wrong, it doesn't work that way," but doing so does not serve our purpose of putting the concept to bed, witness all the re-occurrence of this or very similar concepts on this thread. Gs, I suggest that you post your document, not a link to a file, on a new thread here on the New Physics sub-forum http://forum.nasaspaceflight.com/index.php?board=73.0 and that the responders explain in detail just exactly how your proposed concept behaves and fails.

I too, believe it fails in the classic Newtonian physics case where the center of mass and the center of momentum are the same point, but we are fortunate that there is more to modern physics than Newton. Maybe it doesn't always fail? To find for sure, go ahead and post a new thread to allow unobstructed discussion of the concept. JMO

[OnlyMe]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

I was unable to open the PDF so I am unsure just what you were responding to. That said on the face of it your statement is false, because heat is a measure of the (more or less randomized) momentum of a group of involved atoms and molecules.

Wrong. Heat is a randomized motion  with an average momentum of zero. Heat does not carry, nor transfer momentum.

As I said I could not open the linked PDF, so my comments are only to the issue of whether the momentum associated with the collision of two objects, is at least partly converted to thermal energy...

Take a look at the last analysis of the Pioneer Anomoly. Do a search on Pioneer Anomoly Solved. Yes they are talking about radiant heat, but that radiant heat began as randomized momentum...

The only way you could exclude the randomized motion associated with heat from momentum and even discussions of CoM is if you could somehow argue that thermal energy (heat) and associated randomized motion represents a closed system.

Strike a metal plate several times with a hammer and you will find that both the metal plate and hammer heat up. Since the only interaction between the two is the impact transferring momentum, a portion of the kinetic energy (momentum) is converted to thermal energy.

Objects in the real world are Not perfect ridged bodies. Since they are not perfect any time two objects impact one another transferring momentum, a portion of the momentum from the impact is randomized as heat.

Under most everyday classical situations it is a small amount. Think! A meteorite from the cold of space burns up passing through the atmosphere, its momentum converted to heat as it collides with the atmosphere. The momentum associated with the transfer of momentum between the meteorite and atmosphere, wind up randomized as heat, in a spectacular display we call shooting stars...

Only when dealing with ideal perfectly ridged bodies, or perhaps low velocity classical collisions, can no part of the initial momentum wind up being randomized has heat.

BTW for a long time now I have thought the CoM issue that comes up repeatedly, and is important to the EmDrive discussion, really ends as a CoE balance. There are many ways that electrical/electromagnetic energy can be used to generate kinetic energy/momentum.., and momentum can then be used to generate both heat and electrical/electromagnetic energy. As long as the energy balances (CoE is satisfied) CoM is conserved.

[Gilbertdrive]

Strike a metal plate several times with a hammer and you will find that both the metal plate and hammer heat up. Since the only interaction between the two is the impact transferring momentum, a portion of the kinetic energy (momentum) is converted to thermal energy.

What do you means by Kinetic energy (momentum) ?
It sounds to me like writing acceleration(mass)

Kinetic energy and momentum are very different.
Kinetic energy is easily converted into thermal energy by any impact.
Momentum is never in GR. The General relativity is constructed by this rule (and some others) Momentum is conserved, even in perfect inelastic collision.
Momentum converted into heat needs totally new physics.

[Monomorphic]

The TM modes seem to have the highest Q for this cavity. Does that make sense? The loop is having its field in the axial direction of the cavity.

Thanks,
Peter

That is because you're using side wall injection. You are going to have a very difficult time (just like NASA did) trying to excite the TE01x modes. For example, I was able to locate TE012 at ~4.407Ghz, but it is VERY weak with the antenna mounted to the side and is very close to a TM mode.

If you move the loop to the center things clear up greatly. Also, FEKO says your antenna wire diameter of 2mm is too much. The ratio of wire radius and length are not ideal. You may need to switch to a thinner wire.

Thanks a lot for the advice and the sim, Monomorphic. I will make a new cavity with 1 mm wire. But, uhh..., how about the supply wires if you move the loop to the center? In a sim it is easy to do, but you will have strong influence of the wires from the side or endplate (either coax or two copper wires).
How about placing the loop on one of the endplates, halfway the center and edge, and opening (B-field) facing the center? The loop is not placed at a maximum then, that's true. I will try it out.
Peter

Added some sketch to the image.

I thought the circumference of a loop antenna should ideally be equal to wavelength. 

[Rodal]

Really simple

No, net momentum is conserved at each collision. It's not 'lost' as heat. It's always balanced. Sorry. 

I was unable to open the PDF so I am unsure just what you were responding to. That said on the face of it your statement is false, because heat is a measure of the (more or less randomized) momentum of a group of involved atoms and molecules.

Wrong. Heat is a randomized motion  with an average momentum of zero. Heat does not carry, nor transfer momentum.

On the other hand, let's consider that the lion share of EM Drive experiments have been conducted at ambient pressure in air.

Comparison of different transport phenomena

Physical Phenomenon             Equation            Transported quantity

Heat conduction                         Fourier's Law       Energy

Viscous Fluid Flow                  Newtonian Fluid   Momentum

Molecular Diffusion                     Fick's law            Mass

All forms of convective heat transfer involve the transport of both heat and momentum.  Both Forced and Natural convection involve the Prandtl number and hence they involve momentum transfer.  This is a result of the fluid dynamics, which is responsible for the transport of momentum.

Forced convection heat transfer in a fluid involves the transport of both momentum and heat, involving  Nusselt number (the ratio of convective to conductive heat transfer across (normal to) the boundary), Reynolds number (ratio of inertial forces to viscous forces), and Prandtl numbers (the ratio of momentum diffusivity to thermal diffusivity.) .











For air at ambient pressure, the Prandtl number is close to 1, and hence the thermal and viscous boundary layers are about the same size (Reynolds analogy). This means that for air at ambient pressure, the diffusion of momentum is the same order of magnitude as thermal diffusion.

Natural or free convection is a function of Grashof (the ratio of the buoyancy to viscous force acting on a fluid) and Prandtl numbers (the ratio of momentum diffusivity to thermal diffusivity.)

Any experiment performed in air, particularly at ambient pressure, involves some form of convective heat transfer, as long as there is a temperature gradient involved.  Therefore, experiments performed in air with a microwave heater: the EM Drive, particularly at ambient pressure, involve the transfer of momentum, and are all suspect. 

The only research experimenters that have reported EM Drive experiments in a vacuum chamber have been NASA and TU Dresden, both of them obtaining orders of magnitude smaller force/InputPower than experimenters performing experiments at ambient pressure.

It is noteworthy, and very disappointing that the inventor, Shawyer, who has been working on this for decades, has failed to this date to report a single experiment performed in a vacuum chamber.

None of these experimenters, to my recollection, have reported computational fluid dynamics  to model convection heat transfer in their experiments.

[Peter Lauwer]

I thought the circumference of a loop antenna should ideally be equal to wavelength.

The Eagleworks guys use much smaller loops: 13.5 mm (circumference ~42 mm ) for 1.94 GHz.  Wavelength ~155 mm, so a little bigger than 1/4 lambda.

[OnlyMe]

Strike a metal plate several times with a hammer and you will find that both the metal plate and hammer heat up. Since the only interaction between the two is the impact transferring momentum, a portion of the kinetic energy (momentum) is converted to thermal energy.

What do you means by Kinetic energy (momentum) ?
It sounds to me like writing acceleration(mass)

Kinetic energy and momentum are very different.
Kinetic energy is easily converted into thermal energy by any impact.
Momentum is never in GR. The General relativity is constructed by this rule (and some others) Momentum is conserved, even in perfect inelastic collision.
Momentum converted into heat needs totally new physics.

Momentum as it is being defined in much of this discussion is from a fixed classical Newtonian framework, which results in p=mv. Looking at momentum relativistically the formula becomes far more complex. What that means is that the formula p=mv is an approximation that works for classical low velocity everyday situations.

Even the everyday formula for kinetic energy K= 0.5mv^2 undergoes changes when dealing with relativistic conditions, so it to is a useful approximation...

To answer the question you began with, "What do you means by Kinetic energy (momentum) ?. In the larger context "momentum" is a specialized subset of the "kinetic energy" of an object. Both of them are dependent on the motion of mass, one in a more limited sense than the other.

A question to consider might be, Can the vibrational motion of an atom within a larger composite object be described as momentum? Classically no, but fundamentally yes.

My point was and remains that heat, when speaking of massive objects, objects composed of mass.., atoms whether solid or fluid.., is a form of the randomized momentum of the individual component parts, atoms/molecules.

General relativity is not dependent on momentum or how we define it, though the momentum of a massive object can affect how its gravitational field propagates, relative to another frame of reference. General relativity is a geometric description of the tidal effects of gravity. It is not the cause of gravity or its tidal effects.

Most of what we think of as the laws of physics today are rooted in a classical Newtonian frame of reference with some limited relativistic adaptation, mostly from observations conducted in particle accelerators.., and how we imagine they scale relativistically, based on the models and theory we use to interpret and describe that portion of the universe and physics that lies beyond our ability to directly observe and measure.

When you speak of momentum as defined classically being conserved even in inelastic colisions, and that heat and momentum are different and unrelated observables, you are expressing model and theory based conclusions.

When I state that heat is a specialized form of momentum, I am changing the scale of observation from a macroscopic context of objects, to a more fundamental scale of the component parts, atoms and molecules of the larger object.

Again the only reason I belabor this issue, is because I believe that the discussion of CoM and CoE are important to the larger discussion of the EmDrive, and that so far it seems to me that most of the CoM debate has been centered on a classical Newtonian interpretation, neglecting the fact that Momentum can originate with Energy and in turn be used to generate Energy. Leaving the major issue one of CoE, rather than CoM from a classical context.

An example might be that no one would question that an electric motor can use electricity, to generate electromagnetic fields, which in turn generate angular momentum.... Because we understand or believe we understand how that works. In the case of an EmDrive, the argument continues to revert to a classical Newtonian interpretation, asking what is it pushing off of.., because we don't understand how microwaves in a sealed box could make the box move.

If the box, the EmDrive does move, which I believe will be confirmed, it may require nothing more than a reinterpretation of our understanding of the laws of physics, as we move beyond the classical Newtonian environment.., even more likely something as simple as coming to recognized an interaction between a resonant EM field and the current flow in the frustum walls and associated EM field.

The over unity issues raised relative to constant acceleration, really should wait until constant acceleration has been proven and then what affect even low end relativistic velocities in space, have on a solid mass.

[Gilbertdrive]

To answer the question you began with, "What do you means by Kinetic energy (momentum) ?. In the larger context "momentum" is a specialized subset of the "kinetic energy" of an object. Both of them are dependent on the motion of mass, one in a more limited sense than the other.

The big difference is that Momentum can be negative, when Kinetic Energy can't.
That is why, when you have a big system, isolated from other systems, and composed of several subsystems, you can give momentum to some subsystems. But the sum of the momentum given is zero. For a positive momentum given to any small subsystem, there is a negative momentum given to some others, and the sum of all the gained momentum is still zero, in standard physics.

When you speak of momentum as defined classically being conserved even in inelastic colisions, and that heat and momentum are different and unrelated observables, you are expressing model and theory based conclusions.

Yes, that is why I had clearly written in GR. My point is not to say that conversion from momentum to heat is impossible, but that it is not compatible with GR.

There are many ways that electrical/electromagnetic energy can be used to generate kinetic energy/momentum.., and momentum can then be used to generate both heat and electrical/electromagnetic energy. As long as the energy balances (CoE is satisfied) CoM is conserved.

What you call CoM is not the standard CoM. The standard CoM means that an isolated system always keep the same momentum. No momentum can be converted into heat according to CoM.

You may develop a new theory where Momentum can be converted into heat. But in that case CoM is not satisfied. Conservation of Momentum means that the momentum can't be converted into energy.

[SeeShells]

I thought the circumference of a loop antenna should ideally be equal to wavelength.

The Eagleworks guys use much smaller loops: 13.5 mm (circumference ~42 mm ) for 1.94 GHz.  Wavelength ~155 mm, so a little bigger than 1/4 lambda.

Start with some basics.
https://en.wikipedia.org/wiki/Loop_antenna
https://en.wikipedia.org/wiki/Loop_antenna#Small_loops_as_transmitting_antennas

ID and OD of a small loop will cause phase differences in radiating fields and in a high Q cavity lead to a higher VWSR.

Serious on forcing a high Q like the optomized magnetic point dipole in FEKO or meep which returns extrondary high Qs because of the way it couples to the magnetic field you need to build a unbuidable antenna.

The next best way is a helical antenna which makes a plane wave although it doesn't fit well in a cavity being very long, it still has low VWSR and couples well to the magnetic field locking a TE mode.



Fit could be just one reason why Shawyer went to a modified quadrifiler helical.

It fits well into the cavity, low VWSR, couples to the fields and can lock in a TEmode.

You could also build one like monomorphic modeled in FEKO for Shawyer's design which works quite well. Or just spend 5 bucks or so and get it from Ebay  http://tinyurl.com/hsa8u2s making sure your frequencies match.


Shell

[OnlyMe]

To answer the question you began with, "What do you means by Kinetic energy (momentum) ?. In the larger context "momentum" is a specialized subset of the "kinetic energy" of an object. Both of them are dependent on the motion of mass, one in a more limited sense than the other.

The big difference is that Momentum can be negative, when Kinetic Energy can't.
That is why, when you have a big system, isolated from other systems, and composed of several subsystems, you can give momentum to some subsystems. But the sum of the momentum given is zero. For a positive momentum given to any small subsystem, there is a negative momentum given to some others, and the sum of all the gained momentum is still zero, in standard physics.

When you speak of momentum as defined classically being conserved even in inelastic colisions, and that heat and momentum are different and unrelated observables, you are expressing model and theory based conclusions.

Yes, that is why I had clearly written in GR. My point is not to say that conversion from momentum to heat is impossible, but that it is not compatible with GR.

There are many ways that electrical/electromagnetic energy can be used to generate kinetic energy/momentum.., and momentum can then be used to generate both heat and electrical/electromagnetic energy. As long as the energy balances (CoE is satisfied) CoM is conserved.

What you call CoM is not the standard CoM. The standard CoM means that an isolated system always keep the same momentum. No momentum can be converted into heat according to CoM.

You may develop a new theory where Momentum can be converted into heat. But in that case CoM is not satisfied. Conservation of Momentum means that the momentum can't be converted into energy.

Everything you are saying appears to be model and theory based interpretations, not observables. Just what I was attempting to point out.

In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.

Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.

Any discussion of the observable momentum of objects or an object's component parts and/CoM within the context of GR, is a projected interpretation of classical Newtonian observations. I am unaware of any direct observations involving either, that are not entirely dependent on model/theory based interpretation.

Momentum can be negative only base on chosen frame of reference and since v^2 is a variable in kinetic energy, it to is dependent on frame of reference. In different ways and to different degrees, but in both cases v is a frame dependent quantity.

We do not know how most of what we think of as the laws of physics transition to the larger context of GR, because we have not and cannot as of yet directly observe and measure any of the underlying observables, over a sufficiently significant variation in the tidal effects of gravitation. We make best guesses, but those are always based on preconceived model and theory based bias.

To,the point we don't know if what we know about CoM, as it involves the motion of objects, is conserved within the context of GR. We don't even know if the speed of light is a constant within the context of the tidal effects of gravitation and thus GR, because we are unable to accurately directly measure the speed of light, within the context of a significant variation in the tidal effects of gravitation.

We know a little bit of what IS with some certainty, and we imagine and project that into and onto the larger context of the greater reality of nature and physics that remains outside direct observation.

Personally I believe we do a very good job, projecting what we know beyond our locally observable environment, but it remains important, especially when dealing with potentially new technologies, to remember just what the limitations of what we know with certainty are.

[wicoe]

In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.

Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.

Here is something that I find really confusing... when we see a small object hit the Earth, we observe that its momentum has changed from non-zero to zero.  On the other hand, we know that the total momentum of the system "earth + object" has not changed, so the Earth must have gained some momentum.  Obviously this cannot be measured, but we know it must be true (otherwise CoM would be violated).  Now when we look at "anomalous thrust" devices (such as EmDrive), we observe that they apparently gain momentum.  It would be logical to assume that this is caused by interaction with some other object (or objects) which are gaining the opposite momentum, but we don't know the mechanism of this interaction yet (woodward effect and interaction with other objects in the universe is one hypothesis).  Why do some people choose to throw away CoM and assume that it's not "pushing against" (interacting with) anything?

[Bob012345]

In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.

Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.

Here is something that I find really confusing... when we see a small object hit the Earth, we observe that its momentum has changed from non-zero to zero.  On the other hand, we know that the total momentum of the system "earth + object" has not changed, so the Earth must have gained some momentum.  Obviously this cannot be measured, but we know it must be true (otherwise CoM would be violated).  Now when we look at "anomalous thrust" devices (such as EmDrive), we observe that they apparently gain momentum.  It would be logical to assume that this is caused by interaction with some other object (or objects) which are gaining the opposite momentum, but we don't know the mechanism of this interaction yet (woodward effect and interaction with other objects in the universe is one hypothesis).  Why do some people choose to throw away CoM and assume that it's not "pushing against" (interacting with) anything?

Because that's how they rationalize the EmDrive can't work at all. I don't know anyone who thinks it does work that argues CoM is not applicable.

[Stormbringer]

In one of the earlier incarnations of this thread I may have posted something about hidden sectors of space time related to disappearing neutrons... The topic is in the popular science media with the publication of new papers related to the topic. So here is the article from which the papers can be found. This is by way of showing that what appears to be a closed system may not be closed at all. (and coincidentally giving me more hope that my pet idea of exotic atoms made of weird particles may be possible.
)
http://phys.org/news/2016-11-dark-hidden-sector.html