NASA selects 3 aneutronic fusion related projects

[Emmet]

NASA today published a list of 30 projects for "NIAC early stage innovation". 3 of them (around 10% maybe) are related to aneutronic fusion, namely the concepts of Mr. Slough, Tarditi and Thibeault.

To me that's another very good sign. Why should anyone think of using boron as a radiation shield in space if it's not needed anyway as fuel?

http://www.nasa.gov/offices/oct/early_s ... tions.html

[Ivy Matt]

I'm not sure I understand your question. Boron is useful for neutron shielding independent of its use as a fusion fuel. The only concept I'm completely convinced has to do with aneutronic fusion is the only one that directly mentions it in the proposal title. I'm curious if Mr. Tarditi has a particular confinement concept in mind.

EDIT: Mr. Tarditi appears to be associated with Ad Astra Rocket Company. His name appears on a number of their publications, and he has an adastratechnologies.com e-mail address. But Ad Astra is focusing on propulsion, not power generation, so I'm still curious if Mr. Tarditi has a particular confinement concept in mind.

[Skipjack]

I thought that John Slough was not using aneutronic fusion, but traditional T-D fusion. Maybe his propulsion concept differs from his reactor concept in this regard?

[KitemanSA]

To me that's another very good sign. Why should anyone think of using boron as a radiation shield in space if it's not needed anyway as fuel?

I was under the impression that the two uses needed different isotopes. The shield is made with 10B and the fuel is 11B, and never the twain shall meet. No?

[Emmet]

I'm not sure I understand your question. Boron is useful for neutron shielding independent of its use as a fusion fuel. The only concept I'm completely convinced has to do with aneutronic fusion is the only one that directly mentions it in the proposal title. I'm curious if Mr. Tarditi has a particular confinement concept in mind.

But Mr. Slough is talking about "direct conversion" which is impossible with a high neutron output destroying the necessary grids around it. His concept takes aneutronic fusion as granted - if not it would be useless!

Many materials maybe good for shielding, I'm not familiar with that. But you mention boron as "useful for neutron shielding" while space radiation contains not so much neutrons as far as I know. In space you always try to save weight so the idea is not far to try to use materials who are needed anyway, especially fuel, for shielding. That's the same with hydrogen.

[Emmet]

To me that's another very good sign. Why should anyone think of using boron as a radiation shield in space if it's not needed anyway as fuel?

I was under the impression that the two uses needed different isotopes. The shield is made with 10B and the fuel is 11B, and never the twain shall meet. No?

Maybe this way the 10B could get enriched to 11B sloughly by sloughly and then extracted and being used as fuel?

[Skipjack]

But Mr. Slough is talking about "direct conversion" which is impossible with a high neutron output destroying the necessary grids around it. His concept takes aneutronic fusion as granted - if not it would be useless!

Not direct conversion to electricity, but direct conversion to propulsion.
Big difference.
http://nextbigfuture.com/2010/12/fusion ... lsion.html
http://msnwllc.com/index_propulsion.html

[Ivy Matt]

But Mr. Slough is talking about "direct conversion" which is impossible with a high neutron output destroying the necessary grids around it. His concept takes aneutronic fusion as granted - if not it would be useless!

"Direct conversion" has a specific meaning to certain people (i.e. fans of Polywell or Focus Fusion), but Mr. Slough may mean something else by the term, such as the "direct conversion" of fusion energy into thrust.

Many materials maybe good for shielding, I'm not familiar with that. But you mention boron as "useful for neutron shielding" while space radiation contains not so much neutrons as far as I know. In space you always try to save weight so the idea is not far to try to use materials who are needed anyway, especially fuel, for shielding. That's the same with hydrogen.

The radiation to be shielded against may not be from outside the spacecraft.

[Emmet]

But Mr. Slough is talking about "direct conversion" which is impossible with a high neutron output destroying the necessary grids around it. His concept takes aneutronic fusion as granted - if not it would be useless!

"Direct conversion" has a specific meaning to certain people (i.e. fans of Polywell or Focus Fusion), but Mr. Slough may mean something else by the term, such as the "direct conversion" of fusion energy into thrust.

Many materials maybe good for shielding, I'm not familiar with that. But you mention boron as "useful for neutron shielding" while space radiation contains not so much neutrons as far as I know. In space you always try to save weight so the idea is not far to try to use materials who are needed anyway, especially fuel, for shielding. That's the same with hydrogen.

The radiation to be shielded against may not be from outside the spacecraft.

Ok. But at least we can asume that there is hope for a lightweight and small fusion reactor - aneutronic or not, direct conversion to electricity or to thrust, boron needed as shielding for the very much reactor or as fuel in the better case. Right?

[Skipjack]

Well John Slough has a concept for both, propulsion and electricity.
The electricity concept uses "traditional" T-D fusion. I am not sure what the propulsion system uses. I think Slough uses it with a variety of fuels.

[Emmet]

Well John Slough has a concept for both, propulsion and electricity.
The electricity concept uses "traditional" T-D fusion. I am not sure what the propulsion system uses. I think Slough uses it with a variety of fuels.

How can the electricity concept use T-D? The propulsion concept may use a variety of fuels but the electricity concept has to be aneutronic by default. Or do you mean generation of electricity for other aplications than propulsion like augmenting the ISS capacities?

[Skipjack]

No, I meant that Slough does not only have concepts for propulsion from fusion reactions, he also has a very realistic concept for a working fusion reactor. I am more familiar with his fusion reactor than his propulsion work. The reactor is a pulsed FRC mirror device that "burns" T-D. Slough thinks that it will work as an economic reactor, because of its (relative) simplicity compared to other devices. He has a 1/3 size prototype (that does not make break even) but he does not have funding to scale his device enough to have a demo reactor.

[tomclarke]

No, I meant that Slough does not only have concepts for propulsion from fusion reactions, he also has a very realistic concept for a working fusion reactor. I am more familiar with his fusion reactor than his propulsion work. The reactor is a pulsed FRC mirror device that "burns" T-D. Slough thinks that it will work as an economic reactor, because of its (relative) simplicity compared to other devices. He has a 1/3 size prototype (that does not make break even) but he does not have funding to scale his device enough to have a demo reactor.

He claims good chance of good scaling. As does EMC2. Although his fusion is T-D the near wall is completely isolated from the expensive bits of the apparatus, and speed can be scaled so that neutron flux is what you want, spread out over different areas - it is really an ideal topology for fusion, if it works.

I can't see why so little funding except that everyone is convinced it will not work. Probably not, but I can't see chances much different from Polywell? And although aneutronic fusion is more glamorous, that does not mean as engineering solution it is necessarily better, as much-needed replacement for fission reactors.

[Emmet]

There is some other really interesting stuff in this list even if it poses more questions than it answers - at least to me:

- "Transformative Reconfiguration"? Planetary rovers which change to being flying/climbing vehicles when needed? How?

- "Regolith Derived Heat Shield" Isn't the heat shield needed for the entry and isn't the regolith coming from the planet's surface which is accesible only after entry?

- "Atmospheric Breathing Electric Thruster for Planetary Exploration" - which planet do they mean? I could think logically only about Venus, Mars and Titan all without oxygen for breathing.

- What is the point with metallic hydrogen as rocket fuel? Is this a (proposed) chemical propulsion or something more exotic?

- "Ghost imaging on space objects", ok why not, maybe sometimes they become visible

[Betruger]

I don't remember anything re: metallic H except that it came up on the news and discussions radar last year (IIRC). Dunno if this is part of the same development:
http://iopscience.iop.org/1742-6596/215/1/012194

edit- Actually I think I'm confusing with lunar Aluminum.