So, bottom line is, "Yes, there is a possibility of the release of a large number of real electrons within the dielectric end of the thruster, via an electron avalanche." Such an electron avalanche was not a design feature of the thruster. And further, we know nothing definitive about the tapered cavity thruster.Is there another mechanism which may have released electrons numbering in the ball park of 10^13 electrons/second? Note that is not a large number of electrons as such things go. The electron lifetime would be on the order of 10^-8 to 10^-9 seconds so at any given instant there only a few 10's of thousands of electrons within the cavity. That is a very small number as plasma densities go. Isn't it reasonable to assume that some small number of air molecules ionized within the cavity to create that small number of electrons?Of course ionized air would result in positively charged ions also but if the cause of the electron acceleration was the magnetic field of the RF wave, then it would not discriminate between ion and electron acceleration forces. Ions would have a larger gyro radius around the magnetic field lines, and gyrate in the opposite direction (?) from the electrons but ultimately they would end up in the same place I think.I'm on a roll here so I'd better stop before I go stupid on you.
Quote from: aero on 09/21/2014 03:45 amSo, bottom line is, "Yes, there is a possibility of the release of a large number of real electrons within the dielectric end of the thruster, via an electron avalanche." Such an electron avalanche was not a design feature of the thruster. And further, we know nothing definitive about the tapered cavity thruster.Is there another mechanism which may have released electrons numbering in the ball park of 10^13 electrons/second? Note that is not a large number of electrons as such things go. The electron lifetime would be on the order of 10^-8 to 10^-9 seconds so at any given instant there only a few 10's of thousands of electrons within the cavity. That is a very small number as plasma densities go. Isn't it reasonable to assume that some small number of air molecules ionized within the cavity to create that small number of electrons?Of course ionized air would result in positively charged ions also but if the cause of the electron acceleration was the magnetic field of the RF wave, then it would not discriminate between ion and electron acceleration forces. Ions would have a larger gyro radius around the magnetic field lines, and gyrate in the opposite direction (?) from the electrons but ultimately they would end up in the same place I think.I'm on a roll here so I'd better stop before I go stupid on you.It depends on a lot of things, like the amount of polarization that is achieved in the PTFE dielectric resonator.This we know: there was no measurable thrust when they removed the PTFE dielectric resonator and the direction of the thrust correlates with the location and polarization of the dielectric resonator.
That's fine then. Due to the small number of electrons needed, we don't really need an avalanche, just some "modest" level of ionization within the dielectric resonator. Unfortunately, didn't I read that they have plans to change the dielectric for the IV&V thruster models?
[quoting another]This resonator material has a relative permittivity that is an order of magnitude higher than our current tapered cavity test article resonator material...
The second case is a bit harder to prove, but still within reach of ordinary algebra:Ek = ½mV² ... kinetic energy as a function of V, again.V = at ... again, now substituteEk = ½ma²t² and remembering that [F = ma]...Ek = F²t²/(2m)
Ek = ½ma²t²
you guyz have lost me Apenas dizendo.
Quote from: JohnFornaro on 09/21/2014 01:37 pmApenas dizendo.For those having difficulties following the recent discussion .... Comprende ?
Apenas dizendo.
How did he get from Ek = ½ma²t² to Ek = F²t²/(2m)?Apenas dizendo.
...
Quote from: JohnFornaro on 09/21/2014 01:37 pmyou guyz have lost me Apenas dizendo.For those having difficulties following the recent discussion between aero, RotoSequence, Notsosureofit and me, we have been analyzing the possibility (among many possible explanations) that the anomalous thrust experimental results may have been due to (unintended) field emission of electrons from the ("Teflon") PTFE dielectric resonator (acting as an unintended electron rocket with Teflon acting as the propellant). If such an explanation for the experimental results would be true, it would mean that the thrust was not at all due to the Quantum Vacuum or to Woodward's transient mass effects, and the dreams of a quick trip to the moons of Jupiter and Saturn using this type of propulsion would be thoroughly dashed. Comprende ?
Well, not quite. The electron supply could be deliberately designed into the thruster using a hot cathode for example. The question becomes, is the thruster reactionless or not? If the electrons somehow penetrate the base plate and exit the system then the RF resonate cavity thruster becomes nothing but an interesting electron thruster using electrons as the reaction mass. It still has a very good Isp but charge imbalance would quickly eliminate the thrust in space. It would show very good performance when tested in a grounded vacuum chamber. But we can reasonably expect that the electron stream exiting the cavity would be detected in testing.If instead the electrons somehow do not exit the cavity, it becomes a reactionless thruster which will allow the benefits of the high Isp of the electron beam without the problem of charge build-up on the cavity. This would be a new and to my mind very useful class of thruster.This leads to my question, "How can the RF waves in the cavity turn the high speed electrons from the axial direction to the sideways direction to impact the side walls without an action in the axial direction?"
This leads to my question, "How can the RF waves in the cavity turn the high speed electrons from the axial direction to the sideways direction to impact the side walls without an action in the axial direction?"
Comprende ?
Quote from: Rodal on 09/21/2014 02:02 pm Comprende ?not sure if this was spanish or portuguese (like in the last JohnFornaro posts).
Just an update from the pictures: There is circuit board material on both ends of the truncated cone. The second layer on the large end seems to be just part of the mount.Does anyone know where the dielectric material is in the cone ?
Frustum Dielectric looks like a simulation of a superconducting cavity. Did the model use a realistic copper wall w/ complex n ??
Frustum Dielectric... model use a realistic copper wall w/ complex n ??