Kkattula:The interaction between the power generation and propulsion functions could end up being a MAJOR show stopper for this dual use approach, especially in regards to the WB electron flux since they are so light weight in comparison to the He4 ions. However, once we've established that the WB-XX fusion reactors have met our power generation expectations, and that the M-E is a real propulsion technology to be pursued, then we should perform a detailed analysis of the interactions between the two subsystems to see if there is a happy operational middle ground where both of these subsystems can perform their intended functions without too many comprises for either. That point is not now, but it is still a future possibility.
Quote from: Star-Drive on 10/08/2009 06:46 pmKkattula:The interaction between the power generation and propulsion functions could end up being a MAJOR show stopper for this dual use approach, especially in regards to the WB electron flux since they are so light weight in comparison to the He4 ions. However, once we've established that the WB-XX fusion reactors have met our power generation expectations, and that the M-E is a real propulsion technology to be pursued, then we should perform a detailed analysis of the interactions between the two subsystems to see if there is a happy operational middle ground where both of these subsystems can perform their intended functions without too many comprises for either. That point is not now, but it is still a future possibility. Yes, if the electrons drop energy in synchrotron radiation when you are trying to generate thrust, you could see a lot of thermalization effects, brehmstrahlung, etc which one wants to minimize in a fuzor, so you may need to have two completely different units, one powering the other.
http://www.physorg.com/news174293159.html , interesting dont you think so ?
Quote from: Lampyridae on 10/06/2009 10:36 amTrouble is, electrons don't mass a lot and you won't get a lot of thrust...Well that depends on how many electrons you are handling plus the mass differential between high speed and low speed sides. If the solid capacitors dielectric atoms can only be varied in mass by 0.001%, and you can instead move 1000 electrons with a mass variance of 50% as they go from .1 c to .999 c from one side of the chamber to the other, and an electron is 0.0005 AMU at rest (thus becoming 0.001 AMU at .999c) then 1000 electrons exhibit a mass variance of 1 AMU per cycle.Because you can move electrons much faster than ions, then you should be able to achieve MUCH higher cycle frequencies with the electrons in the chamber than you could with ions in a dielectric. As the charts that Paul has posted here indicate, higher the frequency, the higher the efficiency and higher the thrust.
Trouble is, electrons don't mass a lot and you won't get a lot of thrust...
One thing neglected in this talk of using electron propulsion is how do you keep the vehicle more or less neutrally charged?
I'm sorry about that. I was wondering what this had to do with the thread. Figured it was some comparison with electric propulsion that drifted a bit.Glancing through the previous posts, I must admit that I don't like the use of electrons in a plasma. The problem is synchrotron radiation. If you're bouncing electrons in a chamber at a significant fraction of the speed of light, you are generating a lot of photons (not sure what their frequency would be) each time you bend the path of the electron. Maybe that could be used to transfer energy to another plasma chamber.
How about some sort of lasing mechanism? Pump energy in to a crystal lattice of atoms, pushing the electrons to a higher energy state, on one side of the centrifuge and discharge on the other side. You might even be able to recycle most of the energy involved (excluding of course that expended on net thrust). It doesn't have the raw energy of relativistic electrons, but the energy density might be better.I wonder if there may even be a way to do this with the nuclei themselves. That is, take a nucleus in the ground state, excite it to a nuclear isomer state and then decay. Glancing around, it appears a better way might be to find a nuclear isomer that decays mostly by beta (electron) decay rather than via gamma ray photons. Perhaps one could even reliably pump that electron in and out of the nucleus.
Quote from: khallow on 10/14/2009 05:14 amGlancing through the previous posts, I must admit that I don't like the use of electrons in a plasma. The problem is synchrotron radiation. If you're bouncing electrons in a chamber at a significant fraction of the speed of light, you are generating a lot of photons (not sure what their frequency would be) each time you bend the path of the electron. Maybe that could be used to transfer energy to another plasma chamber.That was my read too. Question: Why is it that electrons orbiting a nucleus do not emit photons unless they are dropping from higher orbits to lower ones? If an electron emits photons any time you bend its path, then the orbit of an electron around a nucleus should cause light emissions, but it does not. Since it does not, why doesn't it, and can we use that to our advantage with some field effect to make the electrons think they are in orbit around a nucleus while orbiting in the trap?
Glancing through the previous posts, I must admit that I don't like the use of electrons in a plasma. The problem is synchrotron radiation. If you're bouncing electrons in a chamber at a significant fraction of the speed of light, you are generating a lot of photons (not sure what their frequency would be) each time you bend the path of the electron. Maybe that could be used to transfer energy to another plasma chamber.
Obviously given electrons are so active in the plasma of a polywell reactor, there are conditions under which synchrotron radiation is limited. From my reading it appears electrons orbit pretty widely in and out of the potential well in the polywell.
QuoteHow about some sort of lasing mechanism? Pump energy in to a crystal lattice of atoms, pushing the electrons to a higher energy state, on one side of the centrifuge and discharge on the other side. You might even be able to recycle most of the energy involved (excluding of course that expended on net thrust). It doesn't have the raw energy of relativistic electrons, but the energy density might be better.I wonder if there may even be a way to do this with the nuclei themselves. That is, take a nucleus in the ground state, excite it to a nuclear isomer state and then decay. Glancing around, it appears a better way might be to find a nuclear isomer that decays mostly by beta (electron) decay rather than via gamma ray photons. Perhaps one could even reliably pump that electron in and out of the nucleus.Thats an interesting idea. You would need to figure out how to get the electrons to emit from the nucleus all in the same direction. Perhaps by making a Bose-Einstein condensate of high atomic number atoms?
That was my read too. Question: Why is it that electrons orbiting a nucleus do not emit photons unless they are dropping from higher orbits to lower ones? If an electron emits photons any time you bend its path, then the orbit of an electron around a nucleus should cause light emissions, but it does not. Since it does not, why doesn't it, and can we use that to our advantage with some field effect to make the electrons think they are in orbit around a nucleus while orbiting in the trap?
Quote from: mlorrey on 10/14/2009 11:07 amThat was my read too. Question: Why is it that electrons orbiting a nucleus do not emit photons unless they are dropping from higher orbits to lower ones? If an electron emits photons any time you bend its path, then the orbit of an electron around a nucleus should cause light emissions, but it does not. Since it does not, why doesn't it, and can we use that to our advantage with some field effect to make the electrons think they are in orbit around a nucleus while orbiting in the trap?Electrons don't actually orbit the nucleus despite the use of the name orbital. An orbital is a wave function that describes the probability distribution of an electron in that orbital. Don't try to apply any real world analogies at the quantum level, they are almost invariable wrong."Not only is the universe stranger than we imagine, it is stranger that we CAN imagine." -Sir Arthur Eddington
So, question: is the wavelength of the synchrotron radiation relative to the turn radius of electron in the betatron cavity? If so, is there an equation that describes how to calculate it?
Quote from: mlorrey on 10/17/2009 06:19 amSo, question: is the wavelength of the synchrotron radiation relative to the turn radius of electron in the betatron cavity? If so, is there an equation that describes how to calculate it?The wavelength of the synchrotron radiation is relative to the acceleration of the electron. The faster the acceleration the shorter the wavelength. Acceleration is the magnetic field times the velocity of the electron. The turn radius is velocity divided by magnetic field. So increasing the magnetic field is the only way to increase the acceleration.For a given magnetic field, increasing velocity means increasing radius and acceleration is constant. Decreasing radius means decreasing velocity and again acceleration is same as before.But take this all with a grain of salt as I only recall this stuff vaguely.
I would also suspect that there may be similar limits on the performance of solid dielectric capacitor based M-E thrusters, in which you wind up generating a lot of radiation emissions when the mass variations exceed a certain percentage of atomic mass, which drains energy.
Quote from: mlorrey on 10/18/2009 04:36 amI would also suspect that there may be similar limits on the performance of solid dielectric capacitor based M-E thrusters, in which you wind up generating a lot of radiation emissions when the mass variations exceed a certain percentage of atomic mass, which drains energy.I think dialectric losses will rule out any use of solid dialectrics. Losses will be prohibitive.
Well you don't know that for a fact, try reading Woodward's work first.