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Old June 28 2011, 01:34 AM   #18
John O.
Rear Admiral
Location: the bush
Re: The DARPA 100 Year Starship

sojourner wrote: View Post
^Wow! those are some impressive isp numbers! Any idea at this stage on how small a unit this can be built at excluding the external power source? It sounds like it will be great for interplanetary use. Very cool pic to!

Does Bussard's Polywell research have any bearing on your work?
I wish I'd have gotten a pic in jet mode it's a lot more impressive looking!

I'm speaking a little outside my field of expertise because I'm an aerospace engineer and not a plasma physicist but my understanding of the relationship to the Bussard Polywell is that both the IEC and the Polywell devices trace their experimental lineage to the Farnsworth-Fusor device in terms of how the technology evolved via the search for viable magnetic/electrostatic confinement driven fusion devices.

In terms of scalability, I can't say much with any certainty - we haven't done force probe analysis yet so we don't even have an order of magnitude for thrust but we believe (hope!) that it's on the order of 1 N with the device scale and power scale we have now.

You hit on an important design point though - power production is, at present, a size limiting factor when you go to put this thing in space. In the lab, there's separate power supplies for the electromagnets, the IEC grid and the RF power - all of which are not small. The IEC grid is going to require 2-100 kV (I know that's a wide range, let's just say it'll ignite at 2 but a viable engine is probably going to require 50+); the RF power requires 1 kW or more; and I'm not entirely sure on the magnetic power.

One thing I'm actually in charge of investigating at present is the state of current research into permanent magnetic helicon coils - in order to reduce weight by doing away with magnetic power supply.

None of this is classified or restricted information of any sort... it's all in the academic public domain. But it's relatively 'cutting edge' because basically nobody has ever investigated coupling a helicon with an IEC before. My advisor got the idea because he's been in fusion research for nearly 50 years.
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