MIT Talks Plasma Details
Twelve neutrons in 4 experiments reduces the error bars some.hanelyp wrote:The error bars from the few neutrons counted in the WB6 experiment are far larger than any good scientist or engineer could like. WB7 should resolve that problem with much higher quality and quantity of data. I want the polywell to work. Until we get the data we can't really be sure.
More experiments are on the way. Yaaaaaaaaaaaa!
Engineering is the art of making what you want from what you can get at a profit.
For reference, a 2003 study in Zacatecas, Mexico found background neutron radiation of 65 +/- 3 neutrons/hour at 2420 m above sea level.MSimon wrote:Twelve neutrons in 4 experiments reduces the error bars some.hanelyp wrote:The error bars from the few neutrons counted in the WB6 experiment are far larger than any good scientist or engineer could like. WB7 should resolve that problem with much higher quality and quantity of data. I want the polywell to work. Until we get the data we can't really be sure.
More experiments are on the way. Yaaaaaaaaaaaa!
http://tinyurl.com/3dl5n2
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jlumartinez
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Remember that WB-6 tests took only 0.25 milliseconds. The study you are referring founded 65 neutrons/ hour, converting this to the time lasted by a WB-6 experiment you will only see 0.00000451 neutrons/0.25milisecs as average.
If you are able to detect 4 neutrons in 0.25 milliseconds in just an a small part of the whole surrounding surface is because a high rate of fusion reactions are taking place. Anyway I also agree with hanelyp that it is better to have more detectors to avoid criticisms about the measurement.
If you are able to detect 4 neutrons in 0.25 milliseconds in just an a small part of the whole surrounding surface is because a high rate of fusion reactions are taking place. Anyway I also agree with hanelyp that it is better to have more detectors to avoid criticisms about the measurement.
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TheRadicalModerate
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Since we're circling back to the Rider paper yet again, it seems as if that paper makes three fundamental arguments against IEC:
1) That electron losses eat up too much power. Bussard clearly thought that successful electron recirculation solved that problem.
2) The chances of ions in the population gaining enough energy through elastic collisions to be lost out of the well were high enough to prevent net power from taking place.
3) Once enough elastic collisions had effectively thermalized the ion population, losses from bremmstrahlung would also prevent net power from being achieved.
Leaving aside objection #1 (for which there appears to be an answer that I actually understand), I still don't understand why Rider's case for thermalization doesn't hold water. Given enough elastic collisions between ions, there's going to be momentum transfer between them. If that momentum transfer is more-or-less random, why doesn't the plasma thermalize? And, once thermalized, why doesn't Rider's claim that the high energy tail will leak out of the well hold?
I'm sure this has all been discussed before--apologies for not quite getting it yet. Can somebody explain to my why the ions don't thermalize?
BTW, Simon, somebody's already yanked your paragraph from Wikipedia.
1) That electron losses eat up too much power. Bussard clearly thought that successful electron recirculation solved that problem.
2) The chances of ions in the population gaining enough energy through elastic collisions to be lost out of the well were high enough to prevent net power from taking place.
3) Once enough elastic collisions had effectively thermalized the ion population, losses from bremmstrahlung would also prevent net power from being achieved.
Leaving aside objection #1 (for which there appears to be an answer that I actually understand), I still don't understand why Rider's case for thermalization doesn't hold water. Given enough elastic collisions between ions, there's going to be momentum transfer between them. If that momentum transfer is more-or-less random, why doesn't the plasma thermalize? And, once thermalized, why doesn't Rider's claim that the high energy tail will leak out of the well hold?
I'm sure this has all been discussed before--apologies for not quite getting it yet. Can somebody explain to my why the ions don't thermalize?
BTW, Simon, somebody's already yanked your paragraph from Wikipedia.
As to the wiki folks - screw them. The real work is going on here and elsewhere.
What happens is that the ions do thermalize at the edge of the machine where their energy is low. This renormalizes the energies. This is true because the Maxwellian peak is narrower at lower energies.
Electrons of course thermalize in the center - same result.
Thus the machine tends to re-normalize the ion and electron energies.
Hope that helps.
What happens is that the ions do thermalize at the edge of the machine where their energy is low. This renormalizes the energies. This is true because the Maxwellian peak is narrower at lower energies.
Electrons of course thermalize in the center - same result.
Thus the machine tends to re-normalize the ion and electron energies.
Hope that helps.
Engineering is the art of making what you want from what you can get at a profit.
If the density is high enough for Brem to have an effect, he may be right. But if the density is just right you should be able to ballance the power out from brem loss and have a net gain.
There are a lot of assumptions in all these back of the envelope calculations, and each persons view of which assumptions are important will determine their view of "what works".
Me included. That is why doing the experiment tells you something - it points the way for which set of assumptions is more valid.
Bussard's assumptions are different than Ridder's. Bussard had a lot more experience with real world nuclear reactors than Ridder. We'll see if that makes a difference.
There are a lot of assumptions in all these back of the envelope calculations, and each persons view of which assumptions are important will determine their view of "what works".
Me included. That is why doing the experiment tells you something - it points the way for which set of assumptions is more valid.
Bussard's assumptions are different than Ridder's. Bussard had a lot more experience with real world nuclear reactors than Ridder. We'll see if that makes a difference.
<snip>TheRadicalModerate wrote:Since we're circling back to the Rider paper yet again, it seems as if that paper makes three fundamental arguments against IEC:
At least.
In 4.1.3, he also mentions that a magnetic field designed to decrease the rate of energy transfer (as in Polywell) between electrons and ions due to brehmsstrahlung radiation will induce synchrotron radiation losses as the ions travel through it, though he did concede that having the field at the edge of the plasma could be acceptable by using "multipolar" magnetic fields -- i.e., what a Polywell would look like (I *think*).
To me perhaps the biggest problem with Bussard's claims are those for net energy production based on the larger size reactor (fusion power increasing by the fifth power of size, and net energy production increasing by the seventh power of size). There seems to be no basis for them whatsoever.
Dr. Mike,
Detectors are not real expensive. Maybe $10K per. Maybe $20K. Off the shelf.
As I understand it the Navy put up $1.8 million for 5 people and eqpt. If they got the eqpt from Dr. B's previous experiments - plus a new reactor vessel, I think a detector or two ought to be in the budget.
Detectors are not real expensive. Maybe $10K per. Maybe $20K. Off the shelf.
As I understand it the Navy put up $1.8 million for 5 people and eqpt. If they got the eqpt from Dr. B's previous experiments - plus a new reactor vessel, I think a detector or two ought to be in the budget.
Engineering is the art of making what you want from what you can get at a profit.
Scareduck,
I have checked the scaling laws and they do match physical conditions and the fusions per second law. It is not something magical. It is straight forward from the physics.
First off - power out goes up with volume. Obvious.
Second off particle velocity goes up with B field. That means particle energy goes up with the square of the B field. Since particles are colliding with each other reaction rate goes up as the fourth power of B field.
I have checked the scaling laws and they do match physical conditions and the fusions per second law. It is not something magical. It is straight forward from the physics.
First off - power out goes up with volume. Obvious.
Second off particle velocity goes up with B field. That means particle energy goes up with the square of the B field. Since particles are colliding with each other reaction rate goes up as the fourth power of B field.
Engineering is the art of making what you want from what you can get at a profit.
@ Simon: Yeah, they got the budget for some detectors! For a basement operation like mine it's a different story 
@ scareduck: Bussard left a few notes, but they are cryptic and hard to fully understand. I found one today called "Ion and Electron Flow and Some Critical Radii in Polywell Systems" on the DTIC web site. Within that are references to Krall's work which give several power laws for density distributions within the Polywell. Bussard had good reason to state his power law reference, it's just not clear how he came by it.
I feel like I'm re-inventing the wheel attempting to come up with a physics model that helps me understand the polywell. It is both good and bad - it's good because it acts as a check and I gain insight, it's bad because I'm bush whacking right next to a highway that is already paved.
http://stinet.dtic.mil/oai/oai?verb=get ... =ADA257687
http://stinet.dtic.mil/oai/oai?verb=get ... =ADA257944
maybe these will give you some hints on where the power laws come from.
@ scareduck: Bussard left a few notes, but they are cryptic and hard to fully understand. I found one today called "Ion and Electron Flow and Some Critical Radii in Polywell Systems" on the DTIC web site. Within that are references to Krall's work which give several power laws for density distributions within the Polywell. Bussard had good reason to state his power law reference, it's just not clear how he came by it.
I feel like I'm re-inventing the wheel attempting to come up with a physics model that helps me understand the polywell. It is both good and bad - it's good because it acts as a check and I gain insight, it's bad because I'm bush whacking right next to a highway that is already paved.
http://stinet.dtic.mil/oai/oai?verb=get ... =ADA257687
http://stinet.dtic.mil/oai/oai?verb=get ... =ADA257944
maybe these will give you some hints on where the power laws come from.
One other thing -- Bussard in the Google video suggested that a polywell design for a D-D/D-T machine would have a 1.5-2m radius and a p-B11 machine would have a 2-2.5m radius (starting at about 1:07:00). I seem to remember 10-20m mooted here -- any reason why your numbers were so much larger, M. Simon?