birchoff wrote:thanks for those links. any idea when those files were uploaded to their referenced locations? Given the previously available information it would seem that the next steps are as follows
- Theoretically prove ME
- Refine the current thruster design to attempt to get closer to predicted thrust
The trouble with this is as I've said on many occasions, science doesn't ever prove anything. All it can do is disprove the alternatives. Most people with real science training will note this, but then speak as if the opposite is true, and I'll admit even I do this. For instance, we often speak of "proof of science" as opposed to "proof of technology" but this is not a literal use of the term "proof" and it does tempt us to think wrongly about the task.
All of the lab work Jim has done over the last 20 years is involved in providing the kind of evidence you're here asking about--proof of science or evidence that M-E is real. It's not that Jim isn't trying. The real trouble, IMHO; is that working with a hobbyist's budget, he has simply not had the resources to build and run more commercial designs. My contention is that what is really needed at this point, is proof of technology. So if I may, I'll just note to you what I believe is called for, since I am involved in trying to put together a startup to do just this.
First off, the design needs to be capable of much more thrust. In fact it needs to deliver what we can call "commercial grade" thrust, of at least 20 mN so that it is in the same class as the Hall Effect thrusters found on things like geosynchronous orbit telecommunications satellites. It also has to be capable of continuous operation, be smaller and lighter than a Hall thruster, consume less power, have a longer lifetime, operate across sufficient thermal bandwidth that it can be used in space in direct sunlight at Venus' orbit and in shade, and be reversible. IMHO, a thruster that cannot do all these things is not a commercial grade thruster and any work to improve these thrusters needs to make direct approaches to all these requirements.
Now you can approach these issues one at a time, or several at a time, but you need to know where you're going especially if you are rethinking the design of the device. And I would note, this is not what Jim is doing. He knows for example, that PMN has such a narrow thermal bandwidth that it is not suitable for continuous operation in space, because it would require more power to cool it than to run it, and all that power is added to the power dissipated by the thruster that then needs to be rejected from a spacecraft. There is simply not sufficient utility in a material with a 2*c thermal bandwidth. Also, PMN can't be scaled for higher frequency use, because its k drops off a cliff at about 1 Mhz. The same is true of PZT. So neither of these materials can be used in a commercial grade thruster.
Hence Jim's problem: he can't get serious development funds without more thrust and he can't get more thrust without more serious development funds. The funding is really the issue, and before I can approach that issue, I have to put together a world-class team. That's what I've been working toward for about 9 months now and it is only starting to look promising. Perhaps I'll know something better by January.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis