Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2107593 times)

Offline Rodal

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Dr. Rodal:

I think that the reason why the Neoprean rubber didn't generate any detectable thrust with the ~30W of available power was that it's carbon loaded which increases its RF loss tangent from that of HDPE or PTFE (~0.0004) up to 0.02 which really loads down the net E-field generated in the cavity for a given input power.  And since we think that the thrust effect we are observing is proportional to E-field squared (E^2) that could make a huge difference in performance.

Now please note that I concur with your analysis on the E&M Poynting vector time averaging to zero in the frustums.  For example when the Cannae pillbox cavity's input RF power feed is well Z-matched with a VSWR= ~1.00, the RF Poynting power flow into the cavity is always towards the large OD pancake section of the cavity.  If one envisions the quantum vacuum (Q-V) as a semi-virtual electrical plasma as Dr. White does, that would imply that the Poynting power flow vector would entrain the Q-V plasma and send it on its way toward the pillbox end of the cavity and then out of the cavity, the back-reaction on the cavity should be in the opposite direction towards the RF feed end of the Cannae test article, but the observed thrust vector is opposite to that surmise, i.e. toward the shorter RF sense antenna end of the cavity per the attached slide. 

Now Per the newly authored Q-V plasma simulation code that Dr. White just finished, the equal bidirectional Q-V plasma flow for the Cannae cavity comes from the high-Q pancake section with a Q of ~9,000 for the un-slotted version of the cavity.  However due to the high E-field region created n the throat of the RF feed, this cylindrically shaped high E-field volume acts as an obstruction to the Q-V plasma flow.  This E-field obstruction created in the PTFE cylinder then accelerates the Q-V plasma around it in a Bernoulli like effect that accelerates the Q-V plasma flow coming from the main pillbox cavity.  This unbalanced and accelerated Q-V plasma flow that goes away from the large pill box cavity in the direction of the RF input section is what generates the NET thrust in our model.   

Next, using this new Q-V plasma simulation tool that utilizes the instantaneous E&M fields from COMSOL for one complete RF cycle in 5 degree increments as its input file, we are now seeing why we need the PTFE or HDPE dielectrics in the frustum while using near pure sine wave power levels below ~100W in the ~2.0 GHz frequency range to generate detectable thrust, and why Shawyer and the Chinese didn't while pumping 80W to 2,500W using magnetron RF sources.  We think the reasons are two fold. 

The first is that Shawyer and the Chinese both used magnetron RF sources for their experiments.  An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz.  (These time rate to change of energy modulations increase the Q-V density in our model.) 

The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf.  In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity.  And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW.   Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment. :)

Lastly, due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities.  Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.

BTW, the reason we included the "what-if" Eagleworks can make this thing work solar system trajectory section on our 2014 JPC paper was that we have to continually tell management the value proposition for why they should fund our research, much in the same way we have to convince Chris Bergin here at NSF we really will be talking about space applications for these Q-Thruster like devices, once we get our hands around the physics they are using.  However when we do, the solar system and beyond will be ours for the picking...

Best, Paul M.

Fantastic post, Paul.  We are so lucky that you are still working on this project and that you are reporting this information.  We hope that this project, as you outlined it, gets full funding.

I also love your scientific objectivity, for example, concerning that Dr. White's simulations do not appear to abide by the assumption that the Quantum Vacuum should be indestructible and immutable.  One reason that the mainstream physics community assumes the Quantum Vacuum is indestructible and immutable is because of the experimental observation that a fundamental particle like an electron (or a positron) has the same properties (e.g. mass, charge or spin), regardless of when or where the particle was created, whether now or in the early universe, through astrophysical processes or in a laboratory.  Another reason is that the Quantum Vacuum has what Albert Einstein in 1913 called "Nullpunktsenergie" (zero point energy): the lowest possible (time-averaged) energy that a quantum mechanical physical system may have.

Godspeed ahead :)
« Last Edit: 04/05/2015 08:58 PM by Rodal »

Offline Star One

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If a cubesat experiment in space cannot be done (due to insufficient funding for now), very high power experiments (10-100 kW) in ambient air are the only way to go, to prove the EmDrive does work as expected:

- Shawyer experiments in ambient air (as well as newer superconducting designs) are now kept under a shroud of secrecy. 

- Chinese mid-to-high power experimental results (~ 2000 W) in ambient air are on the contrary regularly published in academic journals, but are still uncertain because Pr. Juan Yang is not able to share additional data, and spurious causes like air currents are not ruled-out.

- Eagleworks ruled-out the possibility of ambient air currents, running the experiments in a hard vacuum. But because the setup needs to be compact and light enough to sit into the vacuum chamber and hang on the sensitive torsion pendulum (power source included), the amp had to be very weak (10 to 30 watts only) and moreover leaked/sparked in that lower pressure environment. Hence, sadly, less than a hundred micronewtons of thrust. Because of the tiny thrust signatures just above the seismic noise, the results published so far created more questions about other possible spurious causes (EM interaction with the torsion pendulum, the walls of the chamber…).

IMHO, only a very high power experiment producing a very high thrust (above a newton and more), and if possible even lift-off, where air flow circulation around the cavity could not account for the enormous thrust measured by equipment and observed with our own eyes, will settle the case. And will open the colonization of our solar system.

Just as an aside why have Shawyer's experiments dropped off the radar?

Offline flux_capacitor

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Just as an aside why have Shawyer's experiments dropped off the radar?

I don't know. I could think of two different possibilities:
- Either the latest superconducting tests are not positive at all, and contrary to Shawyer's expectation, the thrust does not dramatically improve with the Q factor of the cavity. The EmDrive, at least here on earth, would then be a dead-end.
- Or the exact opposite and Shawyer, who runs a private company (SPR Ltd) and filed various patents on the EmDrive, has now signed a contract with one or several big private aerospace companies for the development of new advanced propulsion systems based on the EmDrive technology, and does not want/is forbidden to disclose any information, maybe (more exactly surely if it's the case) because this information is protected under NDA.

All he accepted to answer me when I asked him about the precise dimensions of the Chinese frustum, is that for a number of years, SPR Ltd policy has been to provide worldwide support to universities and national research agencies (including NASA), for who they checked out their EmDrive cavity geometry using the design software SPR Ltd has developed in-house, because he claims commercial finite element software does not give accurate enough results for engineering purposes. But now we must understand the information that has been disclosed to him by the Chinese cannot be passed on to a third party.
« Last Edit: 04/05/2015 10:14 PM by flux_capacitor »

Offline aero

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Quoting Dr. Rodal
Quote
To have confidence on numerical results one should start by comparing the results with known solutions for (at least) simpler cases.  (Particularly for a numerical method, like the Finite Difference Method used in MEEP, that as we have discussed before one can not be assured to converge to a solution? )

 For example, I compared my exact solutions, and they were within 1% or so of COMSOL FEA results for NASA's truncated cone and their experimental results.

Since we are interested in forces, Meep's ability to accurately calculate resonance frequency doesn't enter into the question. (I am provided with the cavity dimensions and drive frequencies, thereby avoiding that question.)

I have calculated a simple case to verify forces and achieved results within 1% of the known values. That is, Meep calculates the radiant force of a plane wave striking an absorbing surface in vacuum as -1.0006645812/c which is well within 1% of 1/c, the exact answer. Further, Meep calculates the radiant force of a plane wave striking a perfectly reflecting surface in vacuum as -2.0295743306/c which is within 1.5% of 2/c, the exact answer.

In these cases, the positive direction is from the detector to the source, so the minus sign is correct.



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Offline Star One

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Just as an aside why have Shawyer's experiments dropped off the radar?

I don't know. I could think of two different possibilities:
- Either the latest superconducting tests are not positive at all, and contrary to Shawyer's expectation, the thrust does not dramatically improve with the Q factor of the cavity. The EmDrive, at least here on earth, would then be a dead-end.
- Or the exact opposite and Shawyer, who runs a private company (SPR Ltd) and filed various patents on the EmDrive, has now signed a contract with one or several big private aerospace companies for the development of new advanced propulsion systems based on the EmDrive technology, and does not want/is forbidden to disclose any information, maybe (more exactly surely if it's the case) because this information is protected under NDA.

All he accepted to answer me when I asked him about the precise dimensions of the Chinese frustum, is that for a number of years, SPR Ltd policy has been to provide worldwide support to universities and national research agencies (including NASA), for who they checked out their EmDrive cavity geometry using the design software SPR Ltd has developed in-house, because he claims commercial finite element software does not give accurate enough results for engineering purposes. But now we must understand the information that has been disclosed to him by the Chinese cannot be passed on to a third party.
Thanks for that informative response. I do wonder if we will hear anything from him at all then for the foreseeable future.:(

Offline Rodal

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Quoting Dr. Rodal
Quote
To have confidence on numerical results one should start by comparing the results with known solutions for (at least) simpler cases.  (Particularly for a numerical method, like the Finite Difference Method used in MEEP, that as we have discussed before one can not be assured to converge to a solution? )

 For example, I compared my exact solutions, and they were within 1% or so of COMSOL FEA results for NASA's truncated cone and their experimental results.

Since we are interested in forces, Meep's ability to accurately calculate resonance frequency doesn't enter into the question. (I am provided with the cavity dimensions and drive frequencies, thereby avoiding that question.)

I have calculated a simple case to verify forces and achieved results within 1% of the known values. That is, Meep calculates the radiant force of a plane wave striking an absorbing surface in vacuum as -1.0006645812/c which is well within 1% of 1/c, the exact answer. Further, Meep calculates the radiant force of a plane wave striking a perfectly reflecting surface in vacuum as -2.0295743306/c which is within 1.5% of 2/c, the exact answer.

In these cases, the positive direction is from the detector to the source, so the minus sign is correct.

Modeling a plane wave striking an absorbing surface is a different problem than modeling the standing waves in a resonating cavity like the EM Drive.

I was referring to images like these ones, that you posted some time ago:



The electromagnetic fields in that image don't look like the electromagnetic fields in the EM Drive, indicating that there was something wrong with your model of the EM Drive.  Since electromagnetic forces are due to the electromagnetic fields, if one doesn't get the electromagnetic fields correctly, then it stands to reason that the calculations of electromagnetic forces in the EM Drive cannot be correct either.

The electromagnetic field surface distributions should look like this for the frequency being tested under partial vacuum by NASA Eagleworks since last December:



« Last Edit: 04/06/2015 01:38 AM by Rodal »

Offline aero

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Yes, that one seems to be off but without looking at the evolution of the fields in time, one cannot determine how far off it is. You've seen my movie showing the fields in perfect resonance but not all of my runs are in precise resonance. When it is only off by a "small" amount, the fields appear to resonate for a few cycles then they collapse giving something like the image above. Then the resonance pattern re-forms. I speculate that it relates to the integral multiple of wavelengths (or half wavelengths) for the various mode indices, and the fact that I am driving the cavity (in cases where I save the field patterns) with an ideal sinusoid. Maybe I should introduce a little noise in the driving signal.

In any case, my focus is on the forces of evanescent waves and although I am sure that you know this, other readers may not so I should explain. Meep flux and force calculations in isolation don't necessarily give correct absolute values, rather the values are typically relative to something. When evaluating values from cavity models, I always normalize the answers to something else, usually 1/c. Because I normalize the force to Newtons/Watt the actual power in the cavity does not drive the solution. Of course it is important, even crucial when conducting experiments, but even the experimental data published is normalized to Newtons/Watt or mN/W or muN/W. So, modelling a plane wave striking an absorbing surface is quite meaningful. Both the flux and the force are reduced for lack of a quality factor (Q=1) but the ratio of the two is the same as always. The cavity contributes more than just a Q factor to the signal though, so it is necessary that I use the cavity particularly as it seems to aid in the creation of evanescent waves, which is my focus.
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Offline aceshigh

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Oh Paul... propellantless thrusters have already so many detractors and skeptics... and you mentioned a LERN power source for them? 


aside the LERN part, your posts are awesome as always.
« Last Edit: 04/06/2015 02:51 AM by aceshigh »

Offline Star-Drive

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Oh Paul... propellantless thrusters have already so many detractors and skeptics... and you mentioned a LERN power source for them? 


aside the LERN part, your posts are awesome as always.

Aces-High:

I don't work directly with LENR R&D, so my sources are all second hand on this topic by nature, but from what've I've been told by very mainstream sources in the field that cold fusion, AKA LENR, can not be and should not be discounted in the mid to long term.  Past that I won't mention it again in this venue.

In the meantime if we discount closed cycle nuclear fission for a space power source due to political issues, all that is left is H2 & CH4 fuel cells and/or solar photovoltaic arrays up to about 300kWe for sure, and maybe pushed up to 500kWe at Earth orbit, but no more for some time to come.   Lets hope that power range is sufficient for the needs of the first generation of exotic thrusters like the EM-Drive and its other brethren.

Best,  Paul M.
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Offline Star-Drive

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Dr. Rodal:

I think that the reason why the Neoprean rubber didn't generate any detectable thrust with the ~30W of available power was that it's carbon loaded which increases its RF loss tangent from that of HDPE or PTFE (~0.0004) up to 0.02 which really loads down the net E-field generated in the cavity for a given input power.  And since we think that the thrust effect we are observing is proportional to E-field squared (E^2) that could make a huge difference in performance.

Now please note that I concur with your analysis on the E&M Poynting vector time averaging to zero in the frustums.  For example when the Cannae pillbox cavity's input RF power feed is well Z-matched with a VSWR= ~1.00, the RF Poynting power flow into the cavity is always towards the large OD pancake section of the cavity.  If one envisions the quantum vacuum (Q-V) as a semi-virtual electrical plasma as Dr. White does, that would imply that the Poynting power flow vector would entrain the Q-V plasma and send it on its way toward the pillbox end of the cavity and then out of the cavity, the back-reaction on the cavity should be in the opposite direction towards the RF feed end of the Cannae test article, but the observed thrust vector is opposite to that surmise, i.e. toward the shorter RF sense antenna end of the cavity per the attached slide. 

Now Per the newly authored Q-V plasma simulation code that Dr. White just finished, the equal bidirectional Q-V plasma flow for the Cannae cavity comes from the high-Q pancake section with a Q of ~9,000 for the un-slotted version of the cavity.  However due to the high E-field region created n the throat of the RF feed, this cylindrically shaped high E-field volume acts as an obstruction to the Q-V plasma flow.  This E-field obstruction created in the PTFE cylinder then accelerates the Q-V plasma around it in a Bernoulli like effect that accelerates the Q-V plasma flow coming from the main pillbox cavity.  This unbalanced and accelerated Q-V plasma flow that goes away from the large pill box cavity in the direction of the RF input section is what generates the NET thrust in our model.   

Next, using this new Q-V plasma simulation tool that utilizes the instantaneous E&M fields from COMSOL for one complete RF cycle in 5 degree increments as its input file, we are now seeing why we need the PTFE or HDPE dielectrics in the frustum while using near pure sine wave power levels below ~100W in the ~2.0 GHz frequency range to generate detectable thrust, and why Shawyer and the Chinese didn't while pumping 80W to 2,500W using magnetron RF sources.  We think the reasons are two fold. 

The first is that Shawyer and the Chinese both used magnetron RF sources for their experiments.  An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz.  (These time rate to change of energy modulations increase the Q-V density in our model.) 

The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf.  In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity.  And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW.   Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment. :)

Lastly, due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities.  Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.

BTW, the reason we included the "what-if" Eagleworks can make this thing work solar system trajectory section on our 2014 JPC paper was that we have to continually tell management the value proposition for why they should fund our research, much in the same way we have to convince Chris Bergin here at NSF we really will be talking about space applications for these Q-Thruster like devices, once we get our hands around the physics they are using.  However when we do, the solar system and beyond will be ours for the picking...

Best, Paul M.

Fantastic post, Paul.  We are so lucky that you are still working on this project and that you are reporting this information.  We hope that this project, as you outlined it, gets full funding.

I also love your scientific objectivity, for example, concerning that Dr. White's simulations do not appear to abide by the assumption that the Quantum Vacuum should be indestructible and immutable.  One reason that the mainstream physics community assumes the Quantum Vacuum is indestructible and immutable is because of the experimental observation that a fundamental particle like an electron (or a positron) has the same properties (e.g. mass, charge or spin), regardless of when or where the particle was created, whether now or in the early universe, through astrophysical processes or in a laboratory.  Another reason is that the Quantum Vacuum has what Albert Einstein in 1913 called "Nullpunktsenergie" (zero point energy): the lowest possible (time-averaged) energy that a quantum mechanical physical system may have.

Godspeed ahead :)


Dr. Rodal:

The Eagleworks first paper on why Q-V longitudinal acoustical wave action rules the subatomic realm, and the epiphany that the electron is NOT unique, as a loner, or in "orbit" around a proton or protons, will be posted on the NASA servers within a few weeks or less.  And from this point on IMO, we are going to find the only "real" thing in this 5 or 6D brane universe is the quantum vacuum and the high and low "weather patterns" that manipulate it.  Meanwhile back to more mundane things, like making balky low power Q-Thrusters work well enough to get my next set of data points required by management.

Best,  Paul M.   
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Offline aceshigh

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Oh Paul... propellantless thrusters have already so many detractors and skeptics... and you mentioned a LERN power source for them? 


aside the LERN part, your posts are awesome as always.

Aces-High:

I don't work directly with LENR R&D, so my sources are all second hand on this topic by nature, but from what've I've been told by very mainstream sources in the field that cold fusion, AKA LENR, can not be and should not be discounted in the mid to long term.  Past that I won't mention it again in this venue.

In the meantime if we discount closed cycle nuclear fission for a space power source due to political issues, all that is left is H2 & CH4 fuel cells and/or solar photovoltaic arrays up to about 300kWe for sure, and maybe pushed up to 500kWe at Earth orbit, but no more for some time to come.   Lets hope that power range is sufficient for the needs of the first generation of exotic thrusters like the EM-Drive and its other brethren.

Best,  Paul M.

Paul, I do not discount LERN in the mid to long term (nor do I count on it, I am just skeptical and will wait). Itīs just that you know that propellantless propulsion and other stuff is already seen a bit like fringe science, with many doubters and negative skeptics who will call the work you guys do at Eagleworks as crackpottery... IF you add LERN to the picture (in a powerpoint, or even here at NSF, since we know that Google finds it all :)), it will only create more problems for Eagleworks and itīs science.

So imho, best to not even mention LERN since itīs not even necessary to mention it. Better to use a hot fusion reactor in the examples... so many projects to choose from, some lightweight, etc. Shielding problems for spacecraft reactors, then are only a question of engineering, not of physics like LERN.

Just my two cents
« Last Edit: 04/06/2015 05:19 AM by aceshigh »

Offline aceshigh

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In the meantime if we discount closed cycle nuclear fission for a space power source due to political issues, all that is left is H2 & CH4 fuel cells and/or solar photovoltaic arrays up to about 300kWe for sure, and maybe pushed up to 500kWe at Earth orbit, but no more for some time to come.   Lets hope that power range is sufficient for the needs of the first generation of exotic thrusters like the EM-Drive and its other brethren.

Best,  Paul M.

if you are counting on LERN mid and long term... why not count on hot fusion at the mid and long term as a power source for EM-Drive? Polywell, General Fusion, Skunkworks, etc.

All are mid to long term, should be light and compact enough to be used on spacecraft, are more engineering problems than physics problems (I mean, we KNOW fusion happens, we know how to make it happen, we just are trying to win over problems like how to get more output power than input power and similar hurdles).

LERN on the other hand has not even be proved to be real yet nor there are valid and accepted theories for why it should happen.

Therefore, it would be much more elegant to include in any EM Thruster paper, hot compact fusion as a power source... more like a "make your bet on WHICH fusion proposal will work and have the specs we need"...

Offline DIYFAN

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LENR
Probably beyond the speculation tolerance of NSF :(  ...

I think Paul's observation is apropos and quite relevant to space flight applications, and should be within the speculation tolerance of NSF.  NASA has a long history of researching LENR even to the point of experimentation and prototypes.  Multiple well-known universities in the U.S. currently have fully-funded LENR research programs.  A well-known Japanese university just funded a LENR research program along with some industry giants from that country.  Airbus has a keen interest and research program in LENR.  Boeing--same.  Rest assured, many if not most governmental and private entities with an interest in space flight have active LENR research programs.  All of which ironically makes LENR seem less speculative in a sense than the EM Drive itself.
« Last Edit: 04/06/2015 06:15 AM by DIYFAN »

Offline aceshigh

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LENR
Probably beyond the speculation tolerance of NSF :(  ...

I think Paul's observation is apropos and quite relevant to space flight applications, and should be within the speculation tolerance of NSF.  NASA has a long history of researching LENR even to the point of experimentation and prototypes.  Multiple well-known universities in the U.S. currently have fully-funded LENR research programs.  A well-known Japanese university just funded a LENR research program along with some industry giants from that country.  Airbus has a keen interest and research program in LENR.  Boeing--same.  Rest assured, many if not most governmental and private entities with an interest in space flight have active LENR research programs.  All of which ironically makes LENR seem less speculative in a sense than the EM Drive itself.

both are somewhat considered fringe science, so associating one with the other makes it über-fringe, which can make it even more difficult to get funding, support, etc

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if you are counting on LERN mid and long term... why not count on hot fusion at the mid and long term as a power source for EM-Drive? Polywell, General Fusion, Skunkworks, etc.

All are mid to long term, should be light and compact enough to be used on spacecraft, are more engineering problems than physics problems (I mean, we KNOW fusion happens, we know how to make it happen, we just are trying to win over problems like how to get more output power than input power and similar hurdles).

LERN on the other hand has not even be proved to be real yet nor there are valid and accepted theories for why it should happen.

Therefore, it would be much more elegant to include in any EM Thruster paper, hot compact fusion as a power source... more like a "make your bet on WHICH fusion proposal will work and have the specs we need"...
Midterm is 5 to ten years? (LM says they're going to knock it out in that timeframe.) That's not my definition of medium to long term. :) That's short term to me. Short term as in:  "OMG! We're late designing a hull to put it in already."
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Offline Star-Drive

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Aces High:

The hot fusion candidates you mentioned all have one major problem.  That being that except for D-T fusion, no hot fusion scheme to date has ever demonstrated breakeven let alone enough energy gain over its input to make it a viable aerospace fusion reactor candidate.  (I believe that the UK D-T fusion reactor may have reached breakeven for a few minute run, but Lord, look at the neutron flux it generates, which is ~70% of a pure fission reactor for a given output power, a pure fission reactor that can be much smaller and lighter than any tokomak reactor can ever be.)  And after seeing what happened during the poly-well fusion reactor saga, I have great doubts as to the claims by any of the current crop of alternate fusion reactor concepts, L-M's optimistic claims about their fusion reactor design concept not withstanding. 

Best, Paul M.
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Offline flux_capacitor

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Aces High:

The hot fusion candidates you mentioned all have one major problem.  That being that except for D-T fusion, no hot fusion scheme to date has ever demonstrated breakeven let alone enough energy gain over its input to make it a viable aerospace fusion reactor candidate.  (I believe that the UK D-T fusion reactor may have reached breakeven for a few minute run, but Lord, look at the neutron flux it generates, which is ~70% of a pure fission reactor for a given output power, a pure fission reactor that can be much smaller and lighter than any tokomak reactor can ever be.)  And after seeing what happened during the poly-well fusion reactor saga, I have great doubts as to the claims by any of the current crop of alternate fusion reactor concepts, L-M's optimistic claims about their fusion reactor design concept not withstanding. 

Best, Paul M.

You're mentioning the Joint European Torus (JET) tokamak. But there are other possible paths for controlled fusion other than tokamaks. Besides Polywell and Lockheed-Martin reactors you've just cited, maybe another scheme could reach breakeven "soon" among the aneutronic p-B11 Dense Plasma Focus fusion from LPP, the (also aneutronic) Colliding Beam Fusion Reactor from Tri Alpha Energy, the colliding FRC Fusion Engine from Helion Energy, the MTF compressor from General Fusion, the MagLIF z-pinch from Sandia National Labs… None of them are based on tokamaks. Whatever, finding an appropriate energy source for the spaceship before proving the EmDrive does work is an interesting thought experiment (and perhaps mandatory for management) but it is a bit putting the cart before the horse in my opinion.

Offline JasonAW3

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Crazy, possibly stupid question;

     Has anyone ever considered a more direct approace to fusion?  Instead of trying to heat a Deuterium / Tritium mix, why not do a set directed streams of high velocity Tritium into a target point, using the equivelent of a particle accelerator?  There has been success at single atom streams at cryogenic tempertures for directing streams of atoms, but I've never read anywhere that anyone has tried this approach.
My God!  It's full of universes!

Offline QuantumG

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Start a new thread.. try to make it space relevant.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline flux_capacitor

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Crazy, possibly stupid question;

     Has anyone ever considered a more direct approace to fusion?  Instead of trying to heat a Deuterium / Tritium mix, why not do a set directed streams of high velocity Tritium into a target point, using the equivelent of a particle accelerator?  There has been success at single atom streams at cryogenic tempertures for directing streams of atoms, but I've never read anywhere that anyone has tried this approach.
It has been tried and it was successful. Even aneutronic fusion reactions have been achieved with lasers in 2005. But how do you extract energy, and how much if you can? As Paul said, the problem is not producing fusion reactions, because we already do know how. It's extracting more power than what has been injected into the reactor to produce those fusion reactions. This is the concept of break-even applied to nuclear fusion. Wikipedia has a good explanation of the concept.

[EDIT]:
Start a new thread.. try to make it space relevant.
What QuantumG said. I'm sorry for being part of the digression. Let's focus on the EmDrive and its space-related flight applications.
« Last Edit: 04/06/2015 01:05 PM by flux_capacitor »

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