[Ivy Matt]

Not being one to miss out on an opportunity for bikeshedding, I voted “no”. Here’s why:

I tend to interpret “Focus Fusion-1” as equivalent to “Focus Fusion Mark I”. Seen this way, fractional marks don’t really make sense to me.

If we’re going to use software development as an analogy (like EMC2 does), on the other hand, I would favor “1.1” over “1.5”. To me, “1.5” means “version 1, release 5”. I would have to be shown how the upcoming redesign is somehow the fifth modification to the current design before I changed my mind on that point. I realize software designers have been playing fast and loose with version numbers for years now, but I see no reason to go along with that.

I suppose another way to look at “1.5” is as a fraction. In other words, “Focus Fusion-1.5” is halfway between “Focus Fusion-1” and “Focus Fusion-2”. (In all fairness, some software designers treat version numbers as fractional, using numbers such as “1.91” while avoiding numbers such as “1.10” for the tenth release of version 1.) I’m not sure I buy the idea that we know how close we are to a hypothetical “Focus Fusion-2”, though.

I wonder, do LPP employees get to vote more than once in this poll? 😉

[Ivy Matt]

Now, why would I want a site I visit regularly to get hit with a DDOS attack? 😉

[Ivy Matt]

The page on aneutronic fusion also mentions the low cross section of p+Li7 but, even though I check it from time to time for the list of fusion reactions, it’s been a while since I read it all the way through. Okay, boron it is, then.

However, I did look up lithium and its compounds. If lithium-7 were to be introduced into a DPF device the way LPP intends to introduce decaborane, lithium hydride (LiH) would be the obvious choice. However, it has a very high melting point and it reacts explosively with water. Sounds like decaborane is a better choice. And, if you don’t mind mixing reactions, there’s also lithium borohydride. Of course, if p+B11 has a better cross section, there’s no point in doing that.

[Ivy Matt]

After reading the article I’m not certain if they meant Li6/Li7+Be9, or if they meant p+Li6/Li7 and p+Be9. I kind of think it’s the latter. I’m not familiar with any fusion reaction involving Be9 as an input, but I am somewhat familiar with the p+Li6 and p+Li7 reactions. The former produces a He4 ion at 1.7 MeV and a He3 ion at 2.3 MeV, for a total of 4 MeV. The latter produces two He4 ions at a total of 17.2 MeV. Lately I’ve been wondering why p+B11 is seen as the “Holy Grail” of aneutronic fusion, and p+Li7 isn’t. There aren’t any downsides to p+Li7 as far as I can tell, and it should be easier for most confinement concepts to achieve.

[Ivy Matt]

Ivy Matt wrote: Regarding the fuel for Focus Fusion, LPP is considering decaborane (B10H14), which is a solid at room temperature. I’m not sure where they get the B11 from…by enriching decaborane, maybe?

Oy, clearly I’m not a chemist. That’s B(sub10)H(sub14), or ten borons, fourteen hydrogens. And obviously there’s no hydrogen-14. :red: Boron-11 is actually more common in nature, but B-10 and B-11 generally occur together.

NoSmoke wrote: I have read Lerner’s (is that the polite way to refer to him here?)

To be honest, I don’t know. Referring to people by their last name alone in written communication is a habit I picked up in the university. However, it does happen to coincide with his forum name.

NoSmoke wrote: comments that p+B11 goes easier at or around the ideal temperature for that reaction but, does it necessarily follow that D+D (for example) would not be as favourable (as p+B11) at the ideal D+D fusion temperature (i.e. a much lower and presumably easier to reach temperature)? Perhaps it has to do with the greater magnetic field that accompanies the p+B11 fusion conditions (?). Anyhow, that’s why I was wondering earlier if D+D could be a possible fall-back route to take.

D+D fusion is certainly easier to achieve (in terms of kilovolts and stress to the spark plug insulators), but I’m not sure about net power from D+D fusion. The reaction produces neutrons and three types of positive ions: protons, tritium*, and helium-3. I imagine the ions could generate electricity directly, and the neutrons could generate electricity the old fashioned way, but I don’t know enough to say how feasible either or both methods of electrical generation are. And there would still be a nuclear waste problem.

However, when I said that heavier gases achieve fusion more easily, I was referring to this:

To see what the consequences of the magnetic field effect are for DPF functioning, we
first use a theoretical model of DPF functioning that can predict conditions in the plasmoid,
given initial conditions of the device. As described by Lerner [12], and Lerner and Peratt
[13], the DPF process can be described quantitatively using only a few basic assumptions.
Using the formulae derived there, Lerner [1] showed that the particle density increases with μ
and z as well as with I, and decreases with increasing r. Physically this is a direct result of the
greater compression ratio that occurs with heavier gases, as is clear from the above relations.
Thus the crucial plasma parameter nτ improves with heavier gases.

See section 3: “Conditions In DPF Plasmoids”. I’m not a physicist, so I have little idea how well my ideas match reality (or physics models, at any rate), but I picture the magnetic field “squishing” the plasmoid, and it makes sense to me that the heavier the element(s), the denser the plasmoid would be. Thus, the Focus Fusion device not only uses plasma’s instability against itself, but it also uses boron’s relatively high (compared to hydrogen) atomic number against itself.

*Speaking of tritium, I recall that this question came up in the Talk Polywell forums: What happens to the tritium that is produced in the current D+D fusion tests? Is there very much of it? I suppose this question would come up with regard to any research program involving D+D fusion, but I didn’t have a satisfactory answer with regard to the LPPX.

[Ivy Matt]

I suppose I wasn’t clear, but it makes sense to me. I hope this makes the sequence of events clearer:

Sept. 11, 2009: Announcement of contract awarded to EMC2
Apr. 30, 2010: Deadline for completion of WB-8 device build
Nov. 1, 2010: First plasma in WB-8
*six months*
Apr. 30, 2011: Deadline for completion of WB-8 testing and delivery of data
Oct. 31, 2011: Deadline for completion of optional WB-8.1 (p+B11) device build
Oct. 31, 2012: Deadline for completion of optional WB-8.1 testing and delivery of data

[Ivy Matt]

Aren’t they all theoretical designs at this point? Of course, some are more theoretical than others. I don’t know what the criteria are for a “contender”, but if there are any aneutronic contenders, I can’t imagine omitting either Tri Alpha or EMC2. Of course, we have a lot less data on either of those alternatives than we do on LPP’s work.

Here, briefly, is the case for EMC2:

In 2005, after experiencing disappointing results (too many electron losses) with the WB-5 device, Dr. Bussard realized that he needed a redesign and hastily constructed the WB-6, in which the magnets had a circular (rather than square) cross-section, and were separated from each other, only joined by small “nubs”. This device was tested in November of 2005, achieving a rate of a billion fusions per second in four tests. During a fifth attempt a short in the magnetic coil damaged the machine and, as funding was running out anyway, the machine was not repaired or rebuilt. This is according to the testimony of Dr. Bussard.

Bussard spent much of 2006 and 2007 attempting to gain funding for his research. That was when he gave his famous Google Tech Talk. In the fall of 2007, shortly before Dr. Bussard’s death, the Navy began to fund EMC2 again. Between 2007 and 2009 EMC2, now led by Dr. Nebel and Dr. Park, physicists on leave from Los Alamos, tested the WB-7 device which, according to them, validated the results obtained from the WB-6 device. They also tested the WB-7.1, a modification to the WB-7.

In the fall of 2009 EMC2 was granted a contract to construct and test the WB-8 device to determine if it will scale as well as Dr. Bussard said it would. This is where EMC2 now stands.

So, to summarize:

Dr. Bussard reported a billion fusions per second in the WB-6.
The Navy resumed funding of EMC2.
EMC2 reported that the WB-7 confirmed the WB-6 results with improved diagnostics.
The Navy granted EMC2 a contract to build the WB-8, with an option to build the WB-8.1 (p+B11).

It’s not much data, and EMC2 could be headed up a dead end, but I’d say they’re well into the testing stage, which puts them past the purely theoretical stage. But, as with any net power fusion reactor design, it still remains at least partly in the realm of theory.

[Ivy Matt]

I’d think neutrons would be preferable to gamma rays. You’re probably thinking of a couple of threads on Talk Polywell, here and here. The reaction under consideration was the p+N15 reaction. The advantage of the reaction is that it uses nitrogen, which is plentiful and gaseous at room temperature. The output is a C12 and a He4 ion, with a total of 5.0 MeV, as compared with 8.7 MeV from p+B11. As nitrogen is plentiful in the atmosphere it seems like a good candidate for a SSTO vehicle. The disadvantages of the p+N15 reaction are that it is more difficult to achieve than p+B11 (but see the next paragraph) and produces somewhat less energy. However, if net power from p+B11 fusion is possible, net power from p+N15 may not be far behind. Another disadvantage of p+N15 fusion is sort of the mirror opposite of a disadvantage of p+B11 fusion (using decaborane, at least). Whereas the input of the p+B11 reaction (decaborane) is solid at room temperature, an output of the p+N15 reaction (C12) is a solid at room temperature and would tend to coat the walls of the vacuum chamber in an ordinary fusion device. In a plasma focus device I imagine most, if not all, of the carbon would end up in the tube containing the coils and possibly on the coils themselves. But that would be an engineering problem….

Regarding D+D fusion, my understanding is that, according to Lerner’s theory, fusion is actually easier with heavier gases in this particular device, so there’s no reason to go with lighter elements that produce more neutronic reactions.

A p+B11 reactor will still need neutron shielding, but the neutrons are short-lived and will decay soon after the reactor is shut down, making maintenance of the reactor relatively safe and obviating the need for long-term storage of spent reactor materials.

I’m with James. I would expect all positive ions within the plasmoid to be expelled in the beam, but the high-energy alpha particles are the most interesting for generating electricity.

I believe I read somewhere on these forums about an experiment in which two plasma focus devices being pointed at each other, but I don’t recall if there were any interesting results. I don’t think LPP is currently looking into it.

Regarding the fuel for Focus Fusion, LPP is considering decaborane (B10H14), which is a solid at room temperature. I’m not sure where they get the B11 from…by enriching decaborane, maybe? There are other boranes that are gases at room temperature but, as boranes are toxic, they would prefer to work with one that is a solid at room temperature, as solids don’t tend to sneak up on you the way gases do.

As to what separates FF-1 from other plasma focus devices, I would say the main difference is that Eric Lerner has a theory for how fusion could work in a plasma focus device and, on a physical level, FF-1 is a small, high-voltage plasma focus device. Other plasma focus devices are either large and high-voltage or small and low-voltage. According to Lerner’s theory the combination of small size and high voltage should produce the best environment for nuclear fusion.

[Ivy Matt]

To be honest, my sources are kind of old:

http://rspa.royalsocietypublishing.org/content/154/881/246.full.pdf

http://rspa.royalsocietypublishing.org/content/154/881/279.full.pdf

But I’m not aware of any newer work on the D+B10 reaction. I get the impression that many nuclear reactions haven’t been studied intensively since the 1950s, or even the 1930s, in some cases, but I could be wrong about that. As for the boron-10 shielding the neutrons in a DPF plasmoid, that’s an interesting idea, and, I presume, one that lies in the realm of the theoretical for now. Perhaps it could be studied after we find out how well the p+B11 reaction works in the FF-1 device.

[Ivy Matt]

Yes and no. The primary reaction produces three alpha particles with a total of 17.5 MeV of energy, twice as much energy as is produced in the p+B11 reaction. However, deuterium fuses easily with itself (relatively speaking), producing neutrons or tritium in two equally possible reactions. Nevertheless, Wikipedia lists the D+He3 reaction as aneutronic, so by Wikipedia’s standards D+B10 should also count as aneutronic. Of course, even p+B11 produces a small amount of neutrons in side reactions.

Also, if I understand correctly, the D+B10 reaction may occasionally produce C11 and a neutron.

[Ivy Matt]

I don’t know…the Force? :cheese:

[Ivy Matt]

Perhaps, with sufficient advances in capacitor and other technologies, a FF device could fit into a lightsaber handle in the not-too-distant future.

I recently had yet another idea, inspired by the Polywell. The handle creates an electron shaft, and the ions cluster around it. Of course, confining the electron shaft is still a problem without external magnets. Perhaps if the electrons could be expelled straight out, slow down, and then be pulled straight back, you could create a blade with a fixed length. However, it would still behave much like a plasma torch without some solid component extending from the handle.

Back to the power source, I found a set of videos in which Michio Kaku expands on his ideas. Incidentally, he covers a lot of the same ideas I went over, but differs in some ways. For instance, he proposes a titanium fan at the base of the handle to draw in the air that will become the plasma. For some reason I had pictured the plasma as coming from a source inside the lightsaber handle, but this idea is more practical, as you don’t have to worry about cramming a gas canister into your crowded handle and then worrying about how long it will last. One possible drawback to this idea: the lightsaber won’t work in a vacuum. But how often do you need to have a lightsaber battle in a vacuum? For the power source Michio Kaku proposes carbon nanotube batteries:

http://www.youtube.com/watch?v=xSNubaa7n9o

http://www.youtube.com/watch?v=wp_Hq1f8-0E

[Ivy Matt]

Color

The lightsaber blade was originally going to be white (not a very coherent color), but the decision to contrast the colors of Darth Vader’s and Obi-Wan’s lightsaber blades was made in post-production of Star Wars. In post-production of Return of the Jedi the blue skies of “Tatooine” required another contrasting color. The Prequels and other additions to Star Wars lore have introduced numerous colors beyond blue, red, and green.

According to Star Wars lore the color of the lightsaber blade is determined by the sort of crystals used in the handle. The lore is pretty consistent on that point. However, since the blades are supposed to be plasma in current lore, I like to think that the composition of the plasma is mostly what determines the color. Maybe Luke Skywalker’s lightsaber in Return of the Jedi had a boron plasma blade. :coolsmirk:

[Ivy Matt]

“Amazingly similar to the REAL thing”? Isn’t the real thing a movie special effect? Is the Real Thing possible?

If it does a good job of duplicating the look of the movie prop and special effect, presumably that would qualify as similar enough for marketing copy. There are other lightsabers out there that look closer to the “real thing”, and have more authentic sound effects as well. They are licensed by Lucasfilm, of course. The more expensive are only half the cost as well, but I don’t believe they have a real plasma “blade”.

The Real Thing

As for the Real Thing, there are somewhat conflicting ideas out there about how a lightsaber works. The Star Wars novelization doesn’t offer much except that it has switches on the handle, a metal disk above the handle that is polished to a mirror brightness, and that there are several small, jewellike components built into both the handle and disk, including a power cell with a surprisingly high energy rating. This is supposedly a description of the Skywalker lightsaber, but I wonder if Alan Dean Foster (Lucas’ ghost writer) was using that prop or the Obi-Wan lightsaber prop for reference.

Lasers

The Star Wars Technical Journal is cautiously terse as well, but gives a little more detail. The handle is “durasteel”, and it contains a power cell, faceted crystallite lenses, and a focusing core. The lightsaber blade is described as a “coherent beam” that bends back upon itself. This is consistent with the idea that the lightsaber blade is a laser beam, as are the frequent references to lightsaber crystals in Star Wars lore. (Also, the young Anakin refers to the lightsaber as a “laser sword”, but there’s no guarantee that the term used by a slave boy on Tatooine has any more scientific precision than the preferred, but more ambiguous term “lightsaber”.) The problem with lasers is that they go on for a lot more than a meter unless absorbed or reflected by a solid object. How a laser beam can be made to curve back on itself nearly 180° is a mystery to me. If I had to devise a concept, I’d say the lightsaber levitates a small mirror when activated, although I’m not sure how it would hold it in place.

“Energy”

I believe I’ve seen the lightsaber blade described as being composed of “pure energy”. According to my current understanding of physics, that is like saying something is composed of “pure movement”. Wookieepedia reaches a compromise by saying the lightsaber blade is composed of “pure plasma energy”.

Plasma

I think a meter-long plasma torch makes more sense than a laser beam, but it still has problems, as the torch will have trouble holding its shape in the lightest breeze, not to mention when it’s being swung about. Some sort of magnetic confinement may work, and Wookieepedia does mention that the lightsaber generates a “strong gyroscopic effect”. However, I have trouble seeing what magnetic geometry would allow the blade to be magnetically confined from the handle. Another possibility is that the lightsaber blade generates its own magnetic field like a Z-pinch device, but it’s still missing an electrode at the tip, and I think a vacuum tube would be necessary as well.

Wookieepedia’s compromise on the blade containment issue is that the plasma blade is confined by a “force containment field”, and that the field forces the blade to curve back on itself “to a negatively charged fissure ringing the emitter”. I’m not sure if that’s a Force containment field, but if it is it presumably doesn’t require operation by an able Force user, or Han Solo would have had a bit of trouble slicing that Tauntaun open.

Filaments?

Now, gradually getting back to reality, for some reason I’m starting to see some kind of a relationship between how the Star Wars lightsaber supposedly works and the plasma sheath produced in a plasma focus device. Of course, the curvature is not nearly as extreme as what you’d need for a lightsaber, but perhaps it’s a start.

More Realistic Schemes

Michio Kaku in Physics of the Impossible has his own idea for a lightsaber. His idea is that the lighsaber handle contains a narrow telescoping tube perforated with holes. When the lightsaber is activated the tube telescopes out and releases plasma through the holes.

Viewed from the present perspective, the lightsaber seems like an impractical weapon, as missile weapons have far outpaced advances in armor, and it doesn’t look like armor will ever get the advantage back. Should advances in armor increase the importance of melee weapons, however, there is a more practical design for a plasma sword, with the hilt and the flat of the blade being composed of solid material, and plasma forming only the cutting edge. The lightsaber has the advantage that its cutting edge is at all angles, although the plasma sword could perhaps be several blades intersecting along the axis to achieve the same advantage. The plasma sword, however, has the advantage that it pretty much already exists, albeit in a smaller form: the plasma scalpel.

[Ivy Matt]

Eric Lerner mentions atmospheric sprites during the Solstice Seminar (part 2 of 5) at about 10:15.

[Author]

Posts