I'm surprised I hadn't seen this posted here yet - http://www.100yss.org/index.html Actually saw an article about it in a news magazine and then found the original website. I may submit an abstract of the nuclear propulsion system I'm working on for my PhD.
That's pretty cool. I wish I had the kind of background that would let me contribute more than saying, "that's pretty cool."
This being done by DARPA is just weird. It feels like something they would do in the Stargate setting to attract characters like Eli.
Just from a cursory glance at their site i think the first steps are not about building an actual ship but to research the basics of long time/long distance projects, i.e. how can people live within this ship for several generations and sustain the mission and how can this be funded. Actual engineering is "only" the last step after they've figured out how to successfully complete the mission. Pretty cool stuff.
Yeah they've already had a deadline asking for "Requests for Information" in which they want people to submit ideas for how such a 100 yr organization might be built, funded, sustained, etc. Also, I sent it on to my PhD advisor - he's given me the green light to submit our research abstract and present if it's selected, woot!
Should we send the Trek ep about turning shit into boots? Or how about that one where Kes needed soil samples for a hydroponics bay?
Are you allowed to tell the general public (schmucks like the rest of us on this board) a little bit about your proposal? I'm curious.
DARPA isn't building anything. If you read the site you'll see that it's just a study in how to develop a path to develop the technologies needed to eventually build a ship.
Correct, it's a technology symposium - DARPA's just organizing it. We take a helicon (which is a tube of plasma excited to extremely high ionization by a specifically tuned RF signal wound around a coil of electromagnets surrounding the tube), use it as a plasma source and inject that plasma into an IEC (which is an experimental fusion device). The motivation was that while fusion does not currently take place to any appreciable degree inside an IEC, it has a mode that's known to act as a plasma jet. In physics research they use what's called the 'star mode' of operation - and jet mode was always avoided because it destroys the internals of the IEC if you don't modify it to allow for the jet to exhaust. If you build a channel (as we have) to allow the jet to exhaust, then it can potentially produce thrust. In the current evolution, it isn't a candidate for interstellar propulsion - but it is most definitely a candidate for satellite, trans-lunar injection and interplanetary propulsion. Isp is in the 4000-200,000 range depending on power levels and efficiencies we still have to work out. Nobody has modeled the electrostatic field in jet mode in an IEC before because it was of no interest, so that's a mystery right now as well. But at present the leading electric propulsion thruster is the Hall Effect Thruster and we think we can out-perform it - plus, the Hall thruster almost always has to use Xenon, which is becoming increasingly expensive and is absolutely not an option for interstellar travel because of the extremely large quantities it would require. Actually just last week we got it to fire in jet mode briefly. There are still a lot of unknowns regarding the right conditions to fire in jet mode. Man it was a thing of beauty! In the future, it may be possible to further develop the IEC concept such that you get fusion taking place and you get a much, much, MUCH hotter plasma coming out (i.e., higher velocity - higher thrust and ISP) in which case it is a candidate for interstellar propulsion. Minus the fusion aspect, the helicon->IEC coupling is similar to VASIMIR but a lot mechanically simpler. Here's a picture but this was just before we got it into jet mode. What you're seeing is a ball of argon plasma (the blue ball) inside a concentric electrostatic grid (the atom looking metal rings), with a hole to allow the plasma to escape the potential well in a specific direction. Unfortunately, it's not quite a jet there, it's diverging into a diffuse spray. As a jet it's a very narrow tight beam with what we believe may be shock patterns like you see in compressible flow.
^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.
Oh don't worry about that. My professional field is IT. I'm just a space technology enthusiast that never got past algebra in high school. I recognize the difference between thrust and ISP and understand the different ideas behind forms of rocket proplusion, but I couldn't tell ya actual physics in mathematical form. Thanks for the info though! It's interesting and an idea I hadn't heard of. Is there a good website for source information? Do you post on www.nasaspaceflight.com at all? I lurk over there to keep up to date on the space industry.
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.