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Old June 28 2011, 04:07 AM   #20
John O.
Rear Admiral
Location: the bush
Re: The DARPA 100 Year Starship

I've lurked over there for a few months now, a buddy of mine from undergrad works at JSC and he told me to go there one day when I needed some info on Juno or Phoenix or something - pretty cool site.

Yeah the neat thing about this design is that unlike VASIMIR, the Isp and thrust should be uncoupled - that is, you should be able to increase/decrease (design to spec) each of them separately based on the scale and power of the helicon vs the IEC. The design specs of the IEC should affect only the Isp and the design specs of the helicon should affect only the thrust (higher plasma density/ionization will produce more thrust).

When I first started working with the lab doing this research I did a lot of looking. There's a lot out there about IECs and a lot out there about helicons, just nothing that talks about the coupling - that is one of the aspects we're pioneering. You can look for a PhD thesis by a guy named Mike Reilly if you're really interested, he did the first 3-dimensional wave modeling of the helicon mode a few years ago, we're using a lot of his original equipment. It's titled, "Three Dimensional Imaging of Helicon Wave Fields Via Magnetic Induction Probes", from 2009. Another good paper is "Experiments on Helicon Plasma Sources" by Chen, 1991.
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