I mean, what do we really know about WB-100? R = 1.5 m, Target Power = +100 MW, ??? What else? And by what else, I include the question of what alternatives will be built into the experimental capabilities? I am concerned that like so many efforts in so many fields, we may see a high fraction of success (break even), but not reach break even. I know WB-100 can't include all things for all people, but some things can be considered.
But first, what is :
Target Q
Fuel: pB11, DD, DT? all three?
Magnets: Copper, Water cooled, N-cooled, Upgradeable design?
Vacuum chamber size?
Unspent fuel recovery system Vital if DT is used.
Waste heat measurement and removal system.
But I'm really most concerned about the question of radius. How sure are we that 1.5 m is right, and how much more does another quarter meter cost. That is to say, "If 1.5 m doesn't achieve net power, what is the chance that 1.75 meter would have?" "1.65 m?" "Can we overdrive the coils?" "Upgrade them?" Because it seems to me that if WB-100 is close but fails to reach goals, another machine will be built and it will be bigger. It would be nice to avoid the Tokamak cycle, I doubt the public would have much patience for it.
What do we know about WB-100?
Correct me if this has already been hashed out, but if WB-6 had .15 M coils, 1.5M would be 10x radius, so 10^7 X WB-6's output.
D-D fusion avg is 3.6MeV per fusion, X 10^9 claimed fusions/second for WB-6.
Converting 3.6MeV to Joules is 5.76E-13J.
That x 10^9 fusions/sec = .00058 watts of fusion for WB-6.
.00058 watts x 10^7 = 5760W for a 1.5M machine at the same 12KV drive voltage. Am I missing anything? Driving it to higher voltages will give you more output, but I'm still way shy of 100MW.
D-D fusion avg is 3.6MeV per fusion, X 10^9 claimed fusions/second for WB-6.
Converting 3.6MeV to Joules is 5.76E-13J.
That x 10^9 fusions/sec = .00058 watts of fusion for WB-6.
.00058 watts x 10^7 = 5760W for a 1.5M machine at the same 12KV drive voltage. Am I missing anything? Driving it to higher voltages will give you more output, but I'm still way shy of 100MW.
Its tricky. But fortunately is has been hashed out. Check this thread:
viewtopic.php?t=366&highlight=wb6+resul ... plant+rx10
If you need more you can use the "Search" option on this forum. Be warned though, finding the right key words is a challenge.
Oh, and the 100 Mw is for pB11 fusion instead of DD fusion.
viewtopic.php?t=366&highlight=wb6+resul ... plant+rx10
If you need more you can use the "Search" option on this forum. Be warned though, finding the right key words is a challenge.
Oh, and the 100 Mw is for pB11 fusion instead of DD fusion.
Aero
30.17cm OD. No ?JohnP wrote:WB-6 had .15 M coils,
Ahh, ? I thought..Aero wrote: Oh, and the 100 Mw is for pB11 fusion instead of DD fusion.
DD break even is 1.5 m, 100MW 2m,
Pb-11 break even is 2m and 100MW is 2.5m.
Looks like the 1000MW PB-11 reactor = 3m coils
DD net power starts at something like 160cm.
http://www.freepatentsonline.com/y2008/0187086.html
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.
I stand Corrected - This is a Quote from the above linked patent.
The smallest size of practical interest is that at which the device will yield net power from the fuel combinations chosen for use. It has been found that the power output of these devices scales approximately as the 7 th power of the device interior radius, R; thus Pf=C1(R̂7), for given conditions of drive energy (set by choice of fuel). Further, that the power gain (ratio of power generated to power required to drive the system) scales as the 5 th power of the size, Gf=C2(R̂5). Normalization of these scaling laws has been done to a variety of experiments and it has been found that the minimum practical size for DD systems is about R=1.5-2 m, and for pB11 systems is about R=2-2.5 m. Both for a plant output of about 100 MWe. Since the scaling is so rapid with size, a small increase from the 100 MWe size suffices to yield 1000 MWe. Conversely, it is clear that there is little interest in building systems at (e.g.) half of this size, as their output will be quite small for large scale applications.
The smallest size of practical interest is that at which the device will yield net power from the fuel combinations chosen for use. It has been found that the power output of these devices scales approximately as the 7 th power of the device interior radius, R; thus Pf=C1(R̂7), for given conditions of drive energy (set by choice of fuel). Further, that the power gain (ratio of power generated to power required to drive the system) scales as the 5 th power of the size, Gf=C2(R̂5). Normalization of these scaling laws has been done to a variety of experiments and it has been found that the minimum practical size for DD systems is about R=1.5-2 m, and for pB11 systems is about R=2-2.5 m. Both for a plant output of about 100 MWe. Since the scaling is so rapid with size, a small increase from the 100 MWe size suffices to yield 1000 MWe. Conversely, it is clear that there is little interest in building systems at (e.g.) half of this size, as their output will be quite small for large scale applications.
Aero
Re: What do we know about WB-100?
Roger, Thanks for the link, the information re-enforces my concern, which, as I wrote initially is:
It looks like ~3 m radius would give a test bed that would be useful for years while specialized machines were built in the drive toward commercialization. There may be a chance of leap-frogging over the operable range of radii for the BFR, but if such risk exists, it is not so great as the risk of falling short and being painted with the tokamak brush. Right now there will be money for fusion, in five years, other avenues will be established and the money will be going to fission plants and alternatives. New money will be much harder to find. Strike while the iron is hot.
Its beginning to look more and more like 1.5 m is significantly to small. Its like we're building an engine for an airplane and giving it just enough power to get off the ground, but not enough that the pilot dares to go wheels up. Remember, the engine is not what the airplane is about, and neither is break-even what this research is about. The WB-100 should be a test bed allowing multiple avenues of research in my opinion. Make it big enough so that the concern is for fuel throttling and heat dissipation, not for tweaking it to get 10% closer to break-even.But I'm really most concerned about the question of radius. How sure are we that 1.5 m is right, and how much more does another quarter meter cost. That is to say, "If 1.5 m doesn't achieve net power, what is the chance that 1.75 meter would have?" "1.65 m?" "Can we overdrive the coils?" "Upgrade them?" Because it seems to me that if WB-100 is close but fails to reach goals, another machine will be built and it will be bigger. It would be nice to avoid the Tokamak cycle, I doubt the public would have much patience for it.
It looks like ~3 m radius would give a test bed that would be useful for years while specialized machines were built in the drive toward commercialization. There may be a chance of leap-frogging over the operable range of radii for the BFR, but if such risk exists, it is not so great as the risk of falling short and being painted with the tokamak brush. Right now there will be money for fusion, in five years, other avenues will be established and the money will be going to fission plants and alternatives. New money will be much harder to find. Strike while the iron is hot.
Aero
Re: What do we know about WB-100?
Guys, building a little bit larger machine will cost a lot more money, with little gain. There will be more material involved (some are expensive), more stresses and so on, and a larger machine means larger building and infrastructure. I think you could estimate the manufacture increase cost at a scaling of R^3, This means a 3 meter machine would cost 8 time as much as a 1.5 meter. The main reason to build the 1.5 meter experimental device is to get to a net power machine at first, that will lead the way for a economically viable commercial design.Aero wrote: It looks like ~3 m radius would give a test bed that would be useful for years while specialized machines were built in the drive toward commercialization. There may be a chance of leap-frogging over the operable range of radii for the BFR, but if such risk exists, it is not so great as the risk of falling short and being painted with the tokamak brush. Right now there will be money for fusion, in five years, other avenues will be established and the money will be going to fission plants and alternatives. New money will be much harder to find. Strike while the iron is hot.
I still think the 1.5M in size should be close enough to the final radius to experiment with the various modes and factors of operation, and produce a good set of design requirements for the commercial versions. Consider this, net power should be attainable with a 0.5 meter device!
What makes you think net power is attainable at 0.5 meter radius? Dr. Bussard's patent as quoted above says,
"the minimum practical size for DD systems is about R=1.5-2 m,..."
What have you learned that Dr. Bussard did not know when he patented his device? And if you mean DT fusion, please don't go there, DT should be tested only as a last resort. My concern is that at 1.5 m, we are building a machine that requires DT fusion for net power.
"the minimum practical size for DD systems is about R=1.5-2 m,..."
What have you learned that Dr. Bussard did not know when he patented his device? And if you mean DT fusion, please don't go there, DT should be tested only as a last resort. My concern is that at 1.5 m, we are building a machine that requires DT fusion for net power.
Aero
The key word is “Practical”. Although a 0.5 meter can get you net power, the initial power plant investment costs plus the operation cost of the power plant are not much less than what would be for a 1.5 meter machine. You can not recover your investment fast enough with a small machine.Aero wrote:What makes you think net power is attainable at 0.5 meter radius? Dr. Bussard's patent as quoted above says,
"the minimum practical size for DD systems is about R=1.5-2 m,..."
What have you learned that Dr. Bussard did not know when he patented his device? And if you mean DT fusion, please don't go there, DT should be tested only as a last resort. My concern is that at 1.5 m, we are building a machine that requires DT fusion for net power.
(and by the way, you will need to sign an NDA to know the answer to the last question
OK, if power losses do scale as B^(1/4)R^2 it does make sense to keep R small and drive the magnets to high power. But iirc, 0.5 m radius is to small to allow cooling for superconducting magnets and even if not, a small reactor with magnets driven to the limit is nothing but an intellectual curiosity. It can't be scaled, can't be standardize it for commercial development, basically it would be just a side trip along the road to fusion power generation.
WB-100 will be a major step toward our understanding of Polywell Fusion and a major step toward the development of fusion power. But it can be a major step toward commercialization itself, if we choose to take the shortest path to commercial fusion power. The first step along that path is to choose the right size machine. I'm not convinced that 1.5 meters is that right size.
WB-100 will be a major step toward our understanding of Polywell Fusion and a major step toward the development of fusion power. But it can be a major step toward commercialization itself, if we choose to take the shortest path to commercial fusion power. The first step along that path is to choose the right size machine. I'm not convinced that 1.5 meters is that right size.
Aero
John-
I didn't make the claim, but one trail of logic would go like this. BFR scaling is really B^4*R^3 as apposed to R^7 which is most often used for convenience as it is thought that B can be scaled as R. Since the scaling depends on both B and R, and since R^7 ~ 17.1 for R=1.5, then B is also proportional to 1.5. So if we set R=0.5, and require B^4*R^3 = 17.1 then we find that B ~2.27 times larger than previously. That may well be doable but we are getting close to 30 Gauss field strength based on a straight scale up of WB-6 field strength.
I didn't make the claim, but one trail of logic would go like this. BFR scaling is really B^4*R^3 as apposed to R^7 which is most often used for convenience as it is thought that B can be scaled as R. Since the scaling depends on both B and R, and since R^7 ~ 17.1 for R=1.5, then B is also proportional to 1.5. So if we set R=0.5, and require B^4*R^3 = 17.1 then we find that B ~2.27 times larger than previously. That may well be doable but we are getting close to 30 Gauss field strength based on a straight scale up of WB-6 field strength.
Aero
Aero, You are correct, a strong B field is the trick. The R^7 factor is really B^4R^3. Now, Dr. Bussard suggested that B~R, this is where the R^7 scaling factor come from. But the field scaling really depend on (cooling scaling)/R and material properties.
For small devices, coils cooling is problematic at best, regardless if this is Copper or SC but it is possible to cool them enough for a short operation cycle time. Also current SC are limited to 5 to 10 Tesla (however, there are some new unobtainium SC in development).
But copper coils are not limited in that way. Using Neon cooled Copper coils would allow you to get to the field you need, and operate for a few seconds, maybe minutes. This would not be fully continuous operation, but it can produce more power then it uses even when considering cooling, if the field is large enough.
For small devices, coils cooling is problematic at best, regardless if this is Copper or SC but it is possible to cool them enough for a short operation cycle time. Also current SC are limited to 5 to 10 Tesla (however, there are some new unobtainium SC in development).
But copper coils are not limited in that way. Using Neon cooled Copper coils would allow you to get to the field you need, and operate for a few seconds, maybe minutes. This would not be fully continuous operation, but it can produce more power then it uses even when considering cooling, if the field is large enough.