I think that NASA would tell even an ex astronaut to get bent if they thought he had no plasma separation. they just cannot afford to waste time and space on the ISS for something that they believe will not work.
i got what he said a few posts ago but your illustration is simple and clear. That said...I think that NASA would tell even an ex astronaut to get bent if they thought he had no plasma separation. they just cannot afford to waste time and space on the ISS for something that they believe will not work. remember in addition to the world's most expensive hourly wages (figuratively) they are paying the astronauts, and consumables for the astronauts and station and premium equipment berthing real estate the test engine will tap a significant portion of the electrical supply while charging up. I also do not think Chang Diaz would overlook the plasma separation part of an engine or be unaware of it. Nor do i think he as CEO of his company which has other lucrative irons in the fire and a rep to maintain if he wants to stay in business; would waste financial support on it if he did not think it would work.
You would be thinking wrong then. Plasma "poop" is made up of charged particles. If you just shoot out positive ions then a massive electric field will form that will be strong enough to pull those ions back to the rocket, thereby cancelling all thrust. That's why ion thrusters also have electron guns, to neutralize the ions, allowing them to leave the rocket system as neutral atoms. Vasimr doesn't use such a neutralizing mechanism. In fact, I've never quite understood how the ions were to be neutralized efficiently. That's what will define how well the ions detach and whether their blue glowy stuff has any kick to it.
Quote from: Raj2014 on 12/24/2014 09:12 pmYou say the VASIMR does not produce thrust, yet in the video I posted, we can see the VASIMR move the Momentum/Impulse response target.Imagine ping pong balls attached to a board by rubber bands. You make a fancy mechanism that will shoot them out really fast but unless you cut the rubber band they will come back and no net thrust will be produced. Such a device could move a 'Momentum/Impulse response target' and still be useless in space. I'm in no position to argue one way or the other but maybe it will help you understand QuantumG's take on the thing.
You say the VASIMR does not produce thrust, yet in the video I posted, we can see the VASIMR move the Momentum/Impulse response target.
What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?
Quote from: Nomadd on 12/25/2014 01:24 pm What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?From the videos of VASIMR, we can see it apparently does work, which they have tested in a vacuum chamber. They will use it for station boosting and to see how well it will work in a real space environment.
Quote from: Raj2014 on 12/25/2014 01:52 pmQuote from: Nomadd on 12/25/2014 01:24 pm What can they prove at the ISS that a simple vacuum chamber wouldn't suffice for?From the videos of VASIMR, we can see it apparently does work, which they have tested in a vacuum chamber. They will use it for station boosting and to see how well it will work in a real space environment.As previously mentioned, there probably isn't a vacuum chamber large enough to prove detachment will occur.The blue glow proves VASIMR produces a plasma. The question is does the plasma continue on to produce a thrust or loops back along the magnetic field and does not produce a thrust. It is possible that the magnetic field will pull the electrons and ions in opposite directions before they recombine as neutral atoms, resulting in no thrust.Theory says it will work, but they'll have to put it in space to prove it.
i think there is a difference in a system that must get from the surface of the earth to orbit. a fail there means a payload is destroyed at the very least. possibly human passengers. and a whole system has a whole lot more points of failure that the blue glowy poop trying to climb back aboard.
Since apparently funding is what stopping them from continuing development of VASIMR, they could start a kickstarter campaign and a petition. I also read that VASIMR could also be used to shield astronauts and spacecraft from radiations, has this been confirmed?
Detailed mapping of the plasma plume has been accomplished at a power level of 100 kW in a volume extending more than 2 m downstream of the exhaust exit, without significant neutral background interaction. This has led to a compelling demonstration of how the plasma effectively flows away from the magnetic nozzle of a VASIMR® type device.(4)
Understanding the physics involved in plasma detachment from magnetic nozzles is well theorized, but lacking in large scale experimental support. We have undertaken an experiment using the 150-m³ variable specific impulse magnetoplasma rocket test facility and VX-200 thruster seeking evidence that detachment occurs and an understanding of the physical processes involved. It was found that the plasma jet in this experiment does indeed detach from the applied magnetic nozzle (peak field ~2 T) in a two part process
Cancel the ISS experiment then, clearly it's not necessary. That's what Ad Astra are saying, right?
