Why single out one specific 'religion'?... Watch Jesus Camp if you haven't already
Scientology:Following beliefs and teachings as laid out by Ron Hubbard. Christianity:Following beliefs and teachings as laid out by Jesus Christ.
From those definitions, Scientology comes out looking really ugly. On one side we have love thy neighbour
and the other
ENEMY SP Order. Fair game. May be deprived of property or injured by any means by any Scientologist without any discipline of the Scientologist. May be tricked, sued or lied to or destroyed.
The wackos in Jesus Camp are no more representative of Christianity than suicide bombers are representative of Islam. Scientology as taught by Hubbard though, espouses very bad behaviour and should be singled out and shown for what it is. With Scientology, it's not just isolated nuts that are the problem. The core teachings of Hubbard himself encouraged destroying critics any way possible and that the entire field of psychiatry is an evil conspiracy.
Scientiology is bad, but do you trully believe that the Christian Church of Rome is any better?
That borders on defending a newspeak using cult with newspeak... Let's start by defining our words; Scientology:Following beliefs and teachings as laid out by Ron Hubbard. Christianity:Following beliefs and teachings as laid out by Jesus Christ.
From those definitions, Scientology comes out looking really ugly. On one side we have love thy neighbour and the other ENEMY SP Order. Fair game. May be deprived of property or injured by any means by any Scientologist without any discipline of the Scientologist. May be tricked, sued or lied to or destroyed.
Calling Christianity and scientology the same things is intellectually offensive unless you are somehow defining them differently than above.
If you can put any new information on the table and put it into perspective, especially with regard to coal-fired stations, I would be very interested in seeing your results.
Look at mercury emissions contributed to coal plants. Good article is here. A good place to start in it: EPA estimated for the 1990 to 1994 timeframe, these sources emitted 158 tons per year. The Agency has recently released an updated national mercury inventory with a 1999 estimate of 117.3 tons per year. As shown in Table 2.1, coal fired power plants remain the largest source type in the inventory. They were estimated in 1999 to emit about 48 tons per year, or over 40% of the US inventory from anthropogenic sources.
That 48 tons of mercury per year isn't from accidents, it's just normal operational pollution. The article you reference discusses tritium pollution. I'm not sure about others, but pretty happily trade mercury emissions for tritium ones any day.
Corruption affects the problems with all power generation equally. It's the hippies running around trying to convince everyone that corruption at a nuke plant is more dangerous than at a coal plant that parent is complaining about.
You ignored the following challenge in your reply: If you want me to care about a specific instance of mis-management, I'm going to have to see some numbers first. I wouldn't be at all surprised if the total radioactive "contamination" was still less than that of a typical coal burning plant.
You said that you lived 2 hrs from a nuke plant that had a disaster. Care to give us the name of the plant and the year of the disaster so we can compare more severe accidents at coal plants. Unless the media has covered up a lot, nuclear power generation hasn't killed near as many people as coal(both directly and indirectly).
I have however, lived two hours away from a Canadian reactor which was mis-managed and unmaintained to the point where the thing was leaking radioactive water into the landscape. This was discovered in a big-scandal-stink, and the power company shortly after held a big public press-conference apologizing for their mistakes and promised transparency and honest ties to the community. Then a week later they were caught hiding another giant fault. The offending reactor went off-line shortly after.
The error in Bussard's claim was the assumption that the ions, after having been scattered in the central region, all reach virtually the same potential height. This is clearly not possible as it would imply you didn't have collisions in the central region, which in turns mean you don't have any fusion.
He assumed that they would return to different potential heights, but that thermalization would return them to a maxwellian potential energy distribution.
In reality, fusion can only occur through high energy ion-ion collisions, and those are the very same collisions that will screw up your non-maxwellian velocity distribution. This would inevitably result in ions reaching dramatically different potential energies in the potential well, in contrast to Bussard's claim that they will thermalise to the same low energy. Thermalisation alone can NEVER take you from a maxwellian to a non-maxwellian energy distribution. Am I missing something fundamental, or are velocity and energy distributions interchangeable? Doesn't having the ions all at the same potential height mean they are all at the same energy? Doesn't a maxwellian energy distribution = uniform potential height? I am honestly asking, many people state this, as yourself, is self evident but I'm just not seeing what I'm missing here.
You can't change the laws of physics. Its the 2nd law of thermodynamics. Anything not in equilibrium (in this case Maxwellian velocity distribution) then is relaxes to this state.... You clearly have no idea what you are talking about. What is your academic background?
I'm just a comp sci grad with a physics minor. If it's as fundamental as the 2nd law of thermodynamics then help me by pointing out what I'm missing. Take 1 ion and introduce it at a given electric potential, it just orbits in and out between ~100% kinetic and ~100% potential energy levels. Continually returning to the same potential level, barring losses to other mechanisms. Take 1k ions introduced at the same potential. They likewise orbit back and forth reaching the same initial potential level, barring losses to some other mechanism. Now let's say on a pass 2 of the ions collide in the centre. Now 1 ion is orbiting to a higher potential, 1 at a lower potential and the rest at the original potential. Isn't this a less uniform energy distribution? Shouldn't the ions be tending towards a Maxwellian energy, rather than velocity, distribution? What am I missing?(Barring losses like Bremms which should bring ions(~uniformly) down to lower potential over time).
A single of-centre collision in the core is enough to give the ions involved dramatically different energies ( and keep in mind, you will have D-D and T-T side collisions as well , or B-B and p-p in the case of p-B fusion ), and they will thus obviously end up at different potential heights. Are you suggesting they would then "thermalize" so that they all end up on the same potential height?
No, they won't all end up at the same potential height. Just enough to overcome the collision/fusion cross section ratio. Higher energy ions are going to be passing through the lower energy ions at the edge every orbit, and yes, thermalizing while doing it. That won't entirely restore the original distribution, but when 999/1000 of the ion lifetime is at the edge mean time to fusion should mean time to maxwellianization.
So, are you stupid, or merely dishonest? The article mentions several kinds of neutron sources. Spontaneous fission sources are one kind. Accelerator (DD or DT fusion) sources are another...
The fact of the matter is, while Bussard touted orders of magnitude higher neutron output than other IEC devices, the absolute neutron production rate wasn't very high compared to other, existing fusion sources.
I'm just a stickler for details like "comparable drive energies". It is dishonest to claim results at 13kV drive are insignificant because a different device can manage similar fusion rates at 120kV. Show me somebody selling fusion devices with 1E9 n/s at less than 20kV drive energies.
Commercial fusor devices can generate on the order of 109 neutrons per second... whos not reading the links?
And Bussard's claim: These four definitive tests showed true Polywell potential well trapping of ions at ca. 10 kV well depth (with a 12.5 kV drive), with total DD fusion neutron output of ca. 2E5 nts over a period of about 0.4 msec; giving an average fusion rate of about 1E9 fus/sec - over 100,000 times higher than the results achieved by Farnsworth/Hirsch for DD at such low energies, and 100x higher than their best with DD even at 150 kV (Ref. 3)
If you can buy a commercial fusor with 1E9 neutrons/sec driven at 12,5kV then please provide a link to it. Otherwise it's irrelevant as we are talking about "at comparable drive conditions".
Where is the math? The charge density in the core can't be significantly far from equilibrium.
That does not mean one can assume that the charge distribution is uniform. If his math is correct we would get much larger yields from the pure fusor devices.
Have you been following research on multiple potential well formation then? Yoshikawa has some very interesting simulation and experimental results. He goes as far as noting: The results strongly suggest that the high neutron production rate should be attributed to not only the well depth but also the unstable behaviour of the potential, i.e. the intermittent peaking of the density in the centre region. A numerical simulation reveals that IEC possesses a favourable dependence of fusion reactions on the injected ion current for the application to a neutron source or a fusion reactor.
He's not alone in looking at the effects of multiple potential well formation on fusor efficiency either. People at Illinois University, University of Wisconsin, and LANL are all quite interested.
The biggest loss in high energy plasmas is from Bremmstrahlung radiation from electrons, the ions thermalize via ion-electron collisions. Even Bussard claim that. Non equilibrium systems make it worse by having low energy electrons, and this pushes the probability of colliding with one up... Oh I don't have my calculations handy, but i could dig them out. They are not publishable because its been published more than once or twice.
And what ion and electron density and velocity distributions would you have used? Calculating Bremms for a plasma with oscillating density distributions is quite device specific. All the harder when virtual cathode and anodes come into play. You can't just average it out and then say good enough. You most certainly can't go dismissing experimental results on such a basis. Even if the experimental results are just for a 0.4msec pulse, that's interesting enough results to maybe see how the confirmation test goes. Thankfully it's been funded so we should get some experimental data to work out what the density and velocity distributions might look like in a year or so.
First of all I am not a layman. I am a physicist, and electrostatic fusion has been a hobby of mine for some time.
I think your lying, here's why: yet normal commercial neutron source fusors get 1e9 events per second wikipedia and 1e8 are achieved at lower voltages and don't need high B fields And then you link to a wiki article on FISSION neutron sources. Sure they don't require any voltages be input, but they aren't DD fusion based either now are they? Bussard was extremely familiar with fusion research and wasn't senile or fool enough to assume people didn't know about existing fusor technologies.
The ions collide with electrons far more often than they fuse This is from your prior post, as I pointed out before the problem with IEC isn't ion-electron collisions. If you really where familiar with physics or even IEC as a hobby you'd not be making that mistake. Ion-ion collisions are, of course, the only thing you're worrying about. First year undergrad's know that for pity sake.
or he thought everyones data on fusion reaction cross sections is completely wrong Then you either didn't read his paper as you claimed or you don't know the cross sections yourself. Bussard does not say that fusion to collision ratios favor fusion. My post included the full quote and you either didn't read it or didn't understand it. Bussard's claim is that the ration of fusion to collision is less than 1-1000. He then states that since electrons are thermalizing in the outer edges for >999/1000 of the time, they will fuse before core collisions maxwellianize them.
Both require non equilibrium plasmas to work as advertised and that just does not work (The ions collide with electrons far more often than they fuse)...Pretending that this is a non issue without backing up with some calculations/data is bad science.
Mod parent down. Ions do not collide with electrons, they collide with each other! This is worse than the article calling KeV(Kilo electron Volts) degrees Kelvin. When spouting off about bad science and such, don't mod up posts getting particle physics 101 stuff wrong.
Both require non equilibrium plasmas to work as advertised and that just does not work (The ions collide with electrons far more often than they fuse). In fact unless they can find a massive flaw in our current understanding of plasma physic thermodynamics neither can break even. Well the Bussard one defiantly, since its constant state.
And Bussard had responded directly to that issue:
Ions spend less than 1/1000 of their lifetime in the dense, high energy but low cross-section core region, and the ratio of Coulomb energy exchange cross-section to fusion cross-section is much less than this, thus thermalization (Maxwellianization) can not occur during a single pass of ions through the core. While some up- and down- scattering does occur in such a single pass, this is so small that edge region collisionality (where the ions are dense and "cold") anneals this out at each pass through the system, thus avoiding buildup of energy spreading in the ion population (Ref. 14).
In layman's terms, the Polywell design fuses ions faster than they maxwellianize, thanks to the ratio of time in core to time in edge. The full high level paper from Bussard can be found here [askmar.com].
You only need to maintain the non-maxwellian distribution long enough for the ions to fuse before they maxwellianize. Thermalization in the outer edge dominates the coulomb interactions from the core more than the collisions dominate the fusion rates. Those are the conditions that allow fusion to occur faster than maxwellianization. No magic, no violation of physics, just a beneficial design that Rider and Nevins both overlooked in their assumptions.
This view is the general consensus of held by physicist, not just my view. And it's a very good thing that science isn't a democracy. There are many researchers who do not agree with the consensus. Some from MIT and University of Wisconsin-Madison.
For a non-maxwellian velocity distribution your problem is that even at optimal energies a collision is much more likely to scatter the ions than it is to cause fusion, and restoring the non-maxwellian velocity distribution will require energy (no, you don't get to violate the second law of thermodynamics I'm afraid ). For capturing X-rays your problem is to achieve a good enough conversion efficiency to make up for the dramatically increased X-ray losses.
With the exception of a few unconfirmed claims, nobody has been able to resolve the above problems (thou Bussard was quite vocal about his polywell device )
Bussard was more than vocal, his last experiments that the navy is now repeating where successful. Here's what Bussard himself had to say about the problem you mention: Ions spend less than 1/1000 of their lifetime in the dense, high energy but low cross-section core region, and the ratio of Coulomb energy exchange cross-section to fusion cross-section is much less than this, thus thermalization (Maxwellianization) can not occur during a single pass of ions through the core. While some up- and down- scattering does occur in such a single pass, this is so small that edge region collisionality (where the ions are dense and "cold") anneals this out at each pass through the system, thus avoiding buildup of energy spreading in the ion population (Ref. 14).
In layman's terms, the Polywell design fuses ions faster than they maxwellianize, thanks to the ratio of time in core to time in edge. The full high level paper from Bussard can be found here.
Your comment that restoring the non-maxwellian velocity distribution will require energy is oversimplified. You only need to maintain the non-maxwellian distribution long enough for the ions to fuse before they maxwellianize. Thermalization in the outer edge dominates the coulomb interactions from the core more than the collisions dominate the fusion rates. Those are the conditions that allow fusion to occur faster than maxwellianization. No magic, no violation of physics, just a beneficial design that Rider and Nevins both overlooked in their assumptions.
He seems to argue that there is a spontaneous process in the system which restores the non-maxwellian distribution because the ions thermalise at low energies at the perimeter of the device. However:
a)Restoring a particle distribution to a non-maxwellian energy distribution requires work. It doesn't matter how you do it...
And your missing the same thing Rider did. Thermalizing a distribution is just nature. Because of the inherent design of all IEC devices, ions spend >90% of their lifetime in the outer edge of the plasma. That means thermalization is working for maintaining a mono-energetic distribution 90% of the time. Energy isn't being lost, no work is being performed. Energy is just naturally being exchanged between low and high energy ions. Basic high school physics still underly plasma behaviours.
work is required to account for the change in entropy. Only if your already assuming conditions... Ions staying in the system naturally thermalize, on average higher energy ions slowing down and lower energy ions speeding up. NO WORK! Ions gaining enough energy from a collision in one pass(or close consecutive passes) to leave the system will be an energy loss. Thermalization works FOR the mono-energetic distribution because of the basic design. Ions spend most of their lives at low kinetic energy thermalizing. A thermalized, maxwellian distribution of ions in the outer edges gives a natural mono-energetic distribution in the core.
Dr. Bussard was so dismissive of Rider's thesis for the same reasons you are putting forward. IEC devices have not previously had a problem maintaining non-maxwellian distributions.
His original intent was to prove the scaling with WB-6. WB-7 and WB-8 were the two alternate designs for full-scale. When WB-6 failed before proving his scaling theories (at least to peer review and potential sponsors), WB7 and WB8 were dropped back to small scale designs.
Sorry, you've got your timeline messed up but good. WB-6 was built in a rush when the team's navy funding had already been terminated(as a smaller part of a R&D line item cut). The hope was that it would reduce electron losses as they predicted. From the results they managed to get, that looked to be the case. Because they were shutting the lab down anyways, they decided to push the equipment harder than they knew it could likely handle. A short in the electromagnet coils burned the machine out as a result. When WB-6 was being built, private funding wasn't even a consideration. Proving scaling theories was performed with many previous designs running with high electron losses to see how fusion power increased as well size grew. WB-7 and WB-8 were only drawn up after Navy funding was gone and Bussard was looking for new money to finish the testing. He stated clearly that he was confident enough he'd prefer to go straight to full scale testing. He repeatedly stated little more information could be gained from more small scale testing. He DID NOT suggest that he was asking for private funding to by pass WB-7 and WB-8. Whether he thought them necessary for the physics or not, he did consider them necessary to mitigate risk for investors. Luckily for him the Navy re-released his funds to build WB-7. Unluckily, it came to late for him. This of course should be a moot argument in a year when results from WB-7 are available.
From Maxwell's equations div B = 0, so magnetic field lines cannot suddenly stop, and thus magnetic fields alone cannot confine charged particles in a plasma which has the same topology as a sphere ( a charged particle that travels along a magnetic field line will escape the confinement ). Then you've plainly not looked at Bussard's design on even a classical physics level, as he agreed with you. The magnets are held at a high positive potential and electrons are allowed to exit through the cusps and be drawn back in by the positive charge. It's an open re-circulating design and reduces electron losses farther than any mirrored design ever could.
Bussard claimed he could avoid thermalisation of the ions, but this is simply not possible in the polywell design since it would require a spontaneous process to transfer energy between the ions in such a way that their overall entropy decreases.
You mean a spontaneous process to transfer energy from high energy ions to low energy ions? Thermalization will do that for you. The key problem was Nevins suggested losses to a high energy tail that would form. Bussard modelled the thermalization at the edges(where ions spent the vast majority of their time) and found it slowed the maxwellianization long enough. Long enough just means longer than the average ion time to fusion.
Without solid data or independent verification of the results, Bussard is still claiming they can skip the intermediate scale testing and go straight to full-scale.
Bussard never claimed smaller scale tests should be skipped all together. In the google talk he comes off as an academic intent on his field, not a nut. His proposed plan always was the construction of WB-7 and WB-8 devices in ~1 year, but that a committement to the full size device should be made in order to higher good people, since good people don't like 1 year contracts so much. Main thing is his plan always was 2 small scale devices be done first. The push for a full scale device was the scaling rules, which the two smaller devices could prove. With scaling of R^5, the benefit of going full scale were compelling to someone who's been dreaming of this for ages and is near the end of their life.
I've read Rider's papers and thesis. He basically goes through the various ways of creating a non-Maxwellian electron/ion distribution, and shows that there are significant problems with those concepts.
I've been through Rider's paper too. He essientially claims that ALL IEC devices of any sort can not maintain a non-maxwellian distribution. However, there is no basis for using the math models of particle distributions that he uses other than that they make the math easier. Read Rostoker.et al for better detail than I can provide. The short quote from the abstract follows: A distribution function like f(v) does not apply to the CBFR, nor to any reactor concept that we are aware of. Basically calling Rider's model flat wrong, just like Bussard.
If you look closer at Yoshikawa's papers after measuring the double well look close and you will notice he makes mentions of "potential for power generation" in the conclusions of the effects the well has on fusion output.
And as I mention in my prior post, MIT has a very recent paper that also supports Bussard's assertion that non-maxwellian distributions can be naturally maintained. Go here for more. Key quote from it is: Further, this synchronization appears to modify the particle distribution so as to maintain the non-maxwellian, beam-like energy profile within a bunch.
There has been a resurgence of interest in IEC lately and it's not just Bussard who thought Rider's model and sweeping assertions where just wrong. Considering his stage in life his "fastest" proof was to just build the thing. Unfortunately for him, he didn't even have that much time. If Rider's paper is as bullet proof as many critics claim, why are so many fusion physicists investigating power generation with IEC? Clearly they aught to know better and be familiar with Rider's work. Rider even includes Bussard in his paper's credits because he consulted him for help in getting a model of polywell function. Bussard would have to have been quite nutty/senile to continue his research after Rider "proved" him wrong. Unless of course Bussard understood IEC better than a grad student new to the subject and was right to call Rider's model wrong.
As for the Polywell design: I simply don't see how cusp losses can be overcome, nor the collisional dumping of energy from the ions to the electrons. The loses are overcome by using an open, recirculating design. Electrons get out the cusps, and are drawn back in by holding the magnetic coils at a high positive potential. The cusps just need to make the electron density sufficiently higher inside than outside. The outside electrons need a low enough density that they don't arc out. The internal electrons need a high enough density to accelerate ions to fusion speeds. A simple enough design, but Bussard's team wasted a long time trying to design a closed mirroring version which they later demonstrated could never achieve low enough loses. A big reason for testing with non-recirculating designs was the easier engineering since they're budget was so small.
Plus, the design team originally modeled all the coils with as a zero thickness circle and couldn't understand that when they built the thing that the coil circle centers had to be spaced apart which caused field losses. After seeing stupid design errors like that, I don't have much faith in the research team, but still the concept is worth investigation.
Actually, they initially designed it with permanent magnets and drove the electrons right into the magnets themselves. But the point was to prove electron densities in the center could get high enough for fusion. Regardless of the mistakes made along the way, the got the concept to work for their final tests and expect some big results from the new WB-7 some time next year.
The catch to these devises appears to be that if you have a strong enough electrostatic field to contain the ions then you will also lose A LOT of high energy electrons (Rider 1995)
And Bussard insisted that Rider's math model was flat out wrong. Recent experiments by Yoshikawa and MIT have both demonstrated that Rider's model is, in fact, wrong. The Polywell design has tremendous merit to it and the experiments that Bussard managed at the end of his life were successful in measuring fusion scaling factors and electron loss factors. From those experimental results Bussard's team rushed together what was expected to be their last device in WB-6. On analyzing the data it generated, it achieved record breaking fusion rates. Now that the navy has re-funded his team to finish WB-7, expect to see some big announcements in a year or so.
For more on Polywell theory and background go here.
Seriously though, weren't there likely alternatives at the time? DDT was possibly a cheaper and/or better marketed solution,
One of the biggest deployments was by the allies at the end of WW2. Dis-infecting prison camp survivors with a DDT dusting was part of the process at medical tents. When you talk big scale deployment cheaper saves lives, it was not about maximizing profit. Similarly DDT usage to hold back malaria in Africa through the 50's and 60's saved lives. Even counting the lives lost to the unforeseen poisoning of the environment, the DDT program saved lots of lives. A solution needn't be perfect, just better than the alternatives. Thankfully we've got better chemicals for much of this now. Similarly, GM crops may eventually reduce chemical use in agriculture. If it could accomplish that, it might be step up from current methods environmentally speaking.
Slashdot Mirror
Why single out one specific 'religion'?
Watch Jesus Camp if you haven't already
Scientology:Following beliefs and teachings as laid out by Ron Hubbard.
Christianity:Following beliefs and teachings as laid out by Jesus Christ.
From those definitions, Scientology comes out looking really ugly. On one side we have
love thy neighbour
and the other
ENEMY SP Order. Fair game. May be deprived of property or injured by any means by any Scientologist without any discipline of the Scientologist. May be tricked, sued or lied to or destroyed.
The wackos in Jesus Camp are no more representative of Christianity than suicide bombers are representative of Islam. Scientology as taught by Hubbard though, espouses very bad behaviour and should be singled out and shown for what it is. With Scientology, it's not just isolated nuts that are the problem. The core teachings of Hubbard himself encouraged destroying critics any way possible and that the entire field of psychiatry is an evil conspiracy.
Scientiology is bad, but do you trully believe that the Christian Church of Rome is any better?
That borders on defending a newspeak using cult with newspeak...
Let's start by defining our words;
Scientology:Following beliefs and teachings as laid out by Ron Hubbard.
Christianity:Following beliefs and teachings as laid out by Jesus Christ.
From those definitions, Scientology comes out looking really ugly. On one side we have
love thy neighbour
and the other
ENEMY SP Order. Fair game. May be deprived of property or injured by any means by any Scientologist without any discipline of the Scientologist. May be tricked, sued or lied to or destroyed.
Calling Christianity and scientology the same things is intellectually offensive unless you are somehow defining them differently than above.
Who are these anti-nuclear hippies, anyway? I've never met one.
followed by:
They're right here.
Mod parent up!
If you can put any new information on the table and put it into perspective, especially with regard to coal-fired stations, I would be very interested in seeing your results.
Look at mercury emissions contributed to coal plants. Good article is here. A good place to start in it:
EPA estimated for the 1990 to 1994 timeframe, these sources emitted 158 tons per year. The Agency has recently released an updated national mercury inventory with a 1999 estimate of 117.3 tons per year. As shown in Table 2.1, coal fired power plants remain the largest source type in the inventory. They were estimated in 1999 to emit about 48 tons per year, or over 40% of the US inventory from anthropogenic sources.
That 48 tons of mercury per year isn't from accidents, it's just normal operational pollution. The article you reference discusses tritium pollution. I'm not sure about others, but pretty happily trade mercury emissions for tritium ones any day.
Corruption is the key problem; not the hippies.
Corruption affects the problems with all power generation equally. It's the hippies running around trying to convince everyone that corruption at a nuke plant is more dangerous than at a coal plant that parent is complaining about.
You ignored the following challenge in your reply:
If you want me to care about a specific instance of mis-management, I'm going to have to see some numbers first. I wouldn't be at all surprised if the total radioactive "contamination" was still less than that of a typical coal burning plant.
You said that you lived 2 hrs from a nuke plant that had a disaster. Care to give us the name of the plant and the year of the disaster so we can compare more severe accidents at coal plants. Unless the media has covered up a lot, nuclear power generation hasn't killed near as many people as coal(both directly and indirectly).
I have however, lived two hours away from a Canadian reactor which was mis-managed and unmaintained to the point where the thing was leaking radioactive water into the landscape. This was discovered in a big-scandal-stink, and the power company shortly after held a big public press-conference apologizing for their mistakes and promised transparency and honest ties to the community. Then a week later they were caught hiding another giant fault. The offending reactor went off-line shortly after.
References please, or is this just an anecdote?
Stephan Wolfram is going "I told ya so."
Wouldn't that be more like "WE told ya so".
The error in Bussard's claim was the assumption that the ions, after having been scattered in the central region, all reach virtually the same potential height. This is clearly not possible as it would imply you didn't have collisions in the central region, which in turns mean you don't have any fusion.
He assumed that they would return to different potential heights, but that thermalization would return them to a maxwellian potential energy distribution.
In reality, fusion can only occur through high energy ion-ion collisions, and those are the very same collisions that will screw up your non-maxwellian velocity distribution. This would inevitably result in ions reaching dramatically different potential energies in the potential well, in contrast to Bussard's claim that they will thermalise to the same low energy. Thermalisation alone can NEVER take you from a maxwellian to a non-maxwellian energy distribution.
Am I missing something fundamental, or are velocity and energy distributions interchangeable? Doesn't having the ions all at the same potential height mean they are all at the same energy? Doesn't a maxwellian energy distribution = uniform potential height? I am honestly asking, many people state this, as yourself, is self evident but I'm just not seeing what I'm missing here.
You can't change the laws of physics. Its the 2nd law of thermodynamics. Anything not in equilibrium (in this case Maxwellian velocity distribution) then is relaxes to this state.
You clearly have no idea what you are talking about. What is your academic background?
I'm just a comp sci grad with a physics minor. If it's as fundamental as the 2nd law of thermodynamics then help me by pointing out what I'm missing.
Take 1 ion and introduce it at a given electric potential, it just orbits in and out between ~100% kinetic and ~100% potential energy levels. Continually returning to the same potential level, barring losses to other mechanisms.
Take 1k ions introduced at the same potential. They likewise orbit back and forth reaching the same initial potential level, barring losses to some other mechanism. Now let's say on a pass 2 of the ions collide in the centre. Now 1 ion is orbiting to a higher potential, 1 at a lower potential and the rest at the original potential. Isn't this a less uniform energy distribution? Shouldn't the ions be tending towards a Maxwellian energy, rather than velocity, distribution? What am I missing?(Barring losses like Bremms which should bring ions(~uniformly) down to lower potential over time).
A single of-centre collision in the core is enough to give the ions involved dramatically different energies ( and keep in mind, you will have D-D and T-T side collisions as well , or B-B and p-p in the case of p-B fusion ), and they will thus obviously end up at different potential heights. Are you suggesting they would then "thermalize" so that they all end up on the same potential height?
No, they won't all end up at the same potential height. Just enough to overcome the collision/fusion cross section ratio. Higher energy ions are going to be passing through the lower energy ions at the edge every orbit, and yes, thermalizing while doing it. That won't entirely restore the original distribution, but when 999/1000 of the ion lifetime is at the edge mean time to fusion should mean time to maxwellianization.
So, are you stupid, or merely dishonest? The article mentions several kinds of neutron sources. Spontaneous fission sources are one kind. Accelerator (DD or DT fusion) sources are another...
The fact of the matter is, while Bussard touted orders of magnitude higher neutron output than other IEC devices, the absolute neutron production rate wasn't very high compared to other, existing fusion sources.
I'm just a stickler for details like "comparable drive energies". It is dishonest to claim results at 13kV drive are insignificant because a different device can manage similar fusion rates at 120kV. Show me somebody selling fusion devices with 1E9 n/s at less than 20kV drive energies.
Commercial fusor devices can generate on the order of 109 neutrons per second ...
whos not reading the links?
And Bussard's claim:
These four definitive tests showed true Polywell potential well trapping of ions at ca. 10 kV well depth (with a 12.5 kV drive), with total DD fusion neutron output of ca. 2E5 nts over a period of about 0.4 msec; giving an average fusion rate of about 1E9 fus/sec - over 100,000 times higher than the results achieved by Farnsworth/Hirsch for DD at such low energies, and 100x higher than their best with DD even at 150 kV (Ref. 3)
If you can buy a commercial fusor with 1E9 neutrons/sec driven at 12,5kV then please provide a link to it. Otherwise it's irrelevant as we are talking about "at comparable drive conditions".
Where is the math? The charge density in the core can't be significantly far from equilibrium.
That does not mean one can assume that the charge distribution is uniform.
If his math is correct we would get much larger yields from the pure fusor devices.
Have you been following research on multiple potential well formation then? Yoshikawa has some very interesting simulation and experimental results. He goes as far as noting:
The results strongly suggest that the high neutron production rate should be attributed to not only the well depth but also the unstable behaviour of the potential, i.e. the intermittent peaking of the density in the centre region. A numerical simulation reveals that IEC possesses a favourable dependence of fusion reactions on the injected ion current for the application to a neutron source or a fusion reactor.
He's not alone in looking at the effects of multiple potential well formation on fusor efficiency either. People at Illinois University, University of Wisconsin, and LANL are all quite interested.
The biggest loss in high energy plasmas is from Bremmstrahlung radiation from electrons, the ions thermalize via ion-electron collisions. Even Bussard claim that. Non equilibrium systems make it worse by having low energy electrons, and this pushes the probability of colliding with one up...
Oh I don't have my calculations handy, but i could dig them out. They are not publishable because its been published more than once or twice.
And what ion and electron density and velocity distributions would you have used? Calculating Bremms for a plasma with oscillating density distributions is quite device specific. All the harder when virtual cathode and anodes come into play. You can't just average it out and then say good enough. You most certainly can't go dismissing experimental results on such a basis. Even if the experimental results are just for a 0.4msec pulse, that's interesting enough results to maybe see how the confirmation test goes. Thankfully it's been funded so we should get some experimental data to work out what the density and velocity distributions might look like in a year or so.
First of all I am not a layman. I am a physicist, and electrostatic fusion has been a hobby of mine for some time.
I think your lying, here's why:
yet normal commercial neutron source fusors get 1e9 events per second wikipedia and 1e8 are achieved at lower voltages and don't need high B fields
And then you link to a wiki article on FISSION neutron sources. Sure they don't require any voltages be input, but they aren't DD fusion based either now are they? Bussard was extremely familiar with fusion research and wasn't senile or fool enough to assume people didn't know about existing fusor technologies.
The ions collide with electrons far more often than they fuse
This is from your prior post, as I pointed out before the problem with IEC isn't ion-electron collisions. If you really where familiar with physics or even IEC as a hobby you'd not be making that mistake. Ion-ion collisions are, of course, the only thing you're worrying about. First year undergrad's know that for pity sake.
or he thought everyones data on fusion reaction cross sections is completely wrong
Then you either didn't read his paper as you claimed or you don't know the cross sections yourself. Bussard does not say that fusion to collision ratios favor fusion. My post included the full quote and you either didn't read it or didn't understand it. Bussard's claim is that the ration of fusion to collision is less than 1-1000. He then states that since electrons are thermalizing in the outer edges for >999/1000 of the time, they will fuse before core collisions maxwellianize them.
Both require non equilibrium plasmas to work as advertised and that just does not work (The ions collide with electrons far more often than they fuse)...Pretending that this is a non issue without backing up with some calculations/data is bad science.
Mod parent down. Ions do not collide with electrons, they collide with each other! This is worse than the article calling KeV(Kilo electron Volts) degrees Kelvin. When spouting off about bad science and such, don't mod up posts getting particle physics 101 stuff wrong.
Both require non equilibrium plasmas to work as advertised and that just does not work (The ions collide with electrons far more often than they fuse). In fact unless they can find a massive flaw in our current understanding of plasma physic thermodynamics neither can break even. Well the Bussard one defiantly, since its constant state.
And Bussard had responded directly to that issue:
Ions spend less than 1/1000 of their lifetime in the dense, high energy but low cross-section core region, and the ratio of Coulomb energy exchange cross-section to fusion cross-section is much less than this, thus thermalization (Maxwellianization) can not occur during a single pass of ions through the core. While some up- and down- scattering does occur in such a single pass, this is so small that edge region collisionality (where the ions are dense and "cold") anneals this out at each pass through the system, thus avoiding buildup of energy spreading in the ion population (Ref. 14).
In layman's terms, the Polywell design fuses ions faster than they maxwellianize, thanks to the ratio of time in core to time in edge. The full high level paper from Bussard can be found here [askmar.com].
You only need to maintain the non-maxwellian distribution long enough for the ions to fuse before they maxwellianize. Thermalization in the outer edge dominates the coulomb interactions from the core more than the collisions dominate the fusion rates. Those are the conditions that allow fusion to occur faster than maxwellianization. No magic, no violation of physics, just a beneficial design that Rider and Nevins both overlooked in their assumptions.
This view is the general consensus of held by physicist, not just my view.
And it's a very good thing that science isn't a democracy. There are many researchers who do not agree with the consensus. Some from MIT and University of Wisconsin-Madison.
Parent was referring to the viability of small scale fusion reactors. ITER isn't precisely small scale.
For a non-maxwellian velocity distribution your problem is that even at optimal energies a collision is much more likely to scatter the ions than it is to cause fusion, and restoring the non-maxwellian velocity distribution will require energy (no, you don't get to violate the second law of thermodynamics I'm afraid ). For capturing X-rays your problem is to achieve a good enough conversion efficiency to make up for the dramatically increased X-ray losses.
With the exception of a few unconfirmed claims, nobody has been able to resolve the above problems (thou Bussard was quite vocal about his polywell device )
Bussard was more than vocal, his last experiments that the navy is now repeating where successful. Here's what Bussard himself had to say about the problem you mention:
Ions spend less than 1/1000 of their lifetime in the dense, high energy but low cross-section core region, and the ratio of Coulomb energy exchange cross-section to fusion cross-section is much less than this, thus thermalization (Maxwellianization) can not occur during a single pass of ions through the core. While some up- and down- scattering does occur in such a single pass, this is so small that edge region collisionality (where the ions are dense and "cold") anneals this out at each pass through the system, thus avoiding buildup of energy spreading in the ion population (Ref. 14).
In layman's terms, the Polywell design fuses ions faster than they maxwellianize, thanks to the ratio of time in core to time in edge. The full high level paper from Bussard can be found here.
Your comment that restoring the non-maxwellian velocity distribution will require energy is oversimplified. You only need to maintain the non-maxwellian distribution long enough for the ions to fuse before they maxwellianize. Thermalization in the outer edge dominates the coulomb interactions from the core more than the collisions dominate the fusion rates. Those are the conditions that allow fusion to occur faster than maxwellianization. No magic, no violation of physics, just a beneficial design that Rider and Nevins both overlooked in their assumptions.
He seems to argue that there is a spontaneous process in the system which restores the non-maxwellian distribution because the ions thermalise at low energies at the perimeter of the device. However:
a)Restoring a particle distribution to a non-maxwellian energy distribution requires work. It doesn't matter how you do it...
And your missing the same thing Rider did. Thermalizing a distribution is just nature. Because of the inherent design of all IEC devices, ions spend >90% of their lifetime in the outer edge of the plasma. That means thermalization is working for maintaining a mono-energetic distribution 90% of the time. Energy isn't being lost, no work is being performed. Energy is just naturally being exchanged between low and high energy ions. Basic high school physics still underly plasma behaviours.
work is required to account for the change in entropy.
Only if your already assuming conditions...
Ions staying in the system naturally thermalize, on average higher energy ions slowing down and lower energy ions speeding up. NO WORK! Ions gaining enough energy from a collision in one pass(or close consecutive passes) to leave the system will be an energy loss. Thermalization works FOR the mono-energetic distribution because of the basic design. Ions spend most of their lives at low kinetic energy thermalizing. A thermalized, maxwellian distribution of ions in the outer edges gives a natural mono-energetic distribution in the core.
Dr. Bussard was so dismissive of Rider's thesis for the same reasons you are putting forward. IEC devices have not previously had a problem maintaining non-maxwellian distributions.
His original intent was to prove the scaling with WB-6. WB-7 and WB-8 were the two alternate designs for full-scale. When WB-6 failed before proving his scaling theories (at least to peer review and potential sponsors), WB7 and WB8 were dropped back to small scale designs.
Sorry, you've got your timeline messed up but good. WB-6 was built in a rush when the team's navy funding had already been terminated(as a smaller part of a R&D line item cut). The hope was that it would reduce electron losses as they predicted. From the results they managed to get, that looked to be the case. Because they were shutting the lab down anyways, they decided to push the equipment harder than they knew it could likely handle. A short in the electromagnet coils burned the machine out as a result.
When WB-6 was being built, private funding wasn't even a consideration. Proving scaling theories was performed with many previous designs running with high electron losses to see how fusion power increased as well size grew. WB-7 and WB-8 were only drawn up after Navy funding was gone and Bussard was looking for new money to finish the testing. He stated clearly that he was confident enough he'd prefer to go straight to full scale testing. He repeatedly stated little more information could be gained from more small scale testing. He DID NOT suggest that he was asking for private funding to by pass WB-7 and WB-8. Whether he thought them necessary for the physics or not, he did consider them necessary to mitigate risk for investors.
Luckily for him the Navy re-released his funds to build WB-7. Unluckily, it came to late for him. This of course should be a moot argument in a year when results from WB-7 are available.
From Maxwell's equations div B = 0, so magnetic field lines cannot suddenly stop, and thus magnetic fields alone cannot confine charged particles in a plasma which has the same topology as a sphere ( a charged particle that travels along a magnetic field line will escape the confinement ).
Then you've plainly not looked at Bussard's design on even a classical physics level, as he agreed with you. The magnets are held at a high positive potential and electrons are allowed to exit through the cusps and be drawn back in by the positive charge. It's an open re-circulating design and reduces electron losses farther than any mirrored design ever could.
Bussard claimed he could avoid thermalisation of the ions, but this is simply not possible in the polywell design since it would require a spontaneous process to transfer energy between the ions in such a way that their overall entropy decreases.
You mean a spontaneous process to transfer energy from high energy ions to low energy ions? Thermalization will do that for you. The key problem was Nevins suggested losses to a high energy tail that would form. Bussard modelled the thermalization at the edges(where ions spent the vast majority of their time) and found it slowed the maxwellianization long enough. Long enough just means longer than the average ion time to fusion.
Without solid data or independent verification of the results, Bussard is still claiming they can skip the intermediate scale testing and go straight to full-scale.
Bussard never claimed smaller scale tests should be skipped all together. In the google talk he comes off as an academic intent on his field, not a nut. His proposed plan always was the construction of WB-7 and WB-8 devices in ~1 year, but that a committement to the full size device should be made in order to higher good people, since good people don't like 1 year contracts so much. Main thing is his plan always was 2 small scale devices be done first. The push for a full scale device was the scaling rules, which the two smaller devices could prove. With scaling of R^5, the benefit of going full scale were compelling to someone who's been dreaming of this for ages and is near the end of their life.
I've read Rider's papers and thesis. He basically goes through the various ways of creating a non-Maxwellian electron/ion distribution, and shows that there are significant problems with those concepts.
.et al for better detail than I can provide. The short quote from the abstract follows:
I've been through Rider's paper too. He essientially claims that ALL IEC devices of any sort can not maintain a non-maxwellian distribution. However, there is no basis for using the math models of particle distributions that he uses other than that they make the math easier. Read Rostoker
A distribution function like f(v) does not apply to the CBFR, nor to any reactor concept that we are aware of.
Basically calling Rider's model flat wrong, just like Bussard.
If you look closer at Yoshikawa's papers after measuring the double well look close and you will notice he makes mentions of "potential for power generation" in the conclusions of the effects the well has on fusion output.
And as I mention in my prior post, MIT has a very recent paper that also supports Bussard's assertion that non-maxwellian distributions can be naturally maintained. Go here for more. Key quote from it is:
Further, this synchronization appears to modify the particle distribution so as to maintain the non-maxwellian, beam-like energy profile within a bunch.
There has been a resurgence of interest in IEC lately and it's not just Bussard who thought Rider's model and sweeping assertions where just wrong. Considering his stage in life his "fastest" proof was to just build the thing. Unfortunately for him, he didn't even have that much time. If Rider's paper is as bullet proof as many critics claim, why are so many fusion physicists investigating power generation with IEC? Clearly they aught to know better and be familiar with Rider's work. Rider even includes Bussard in his paper's credits because he consulted him for help in getting a model of polywell function. Bussard would have to have been quite nutty/senile to continue his research after Rider "proved" him wrong. Unless of course Bussard understood IEC better than a grad student new to the subject and was right to call Rider's model wrong.
As for the Polywell design:
I simply don't see how cusp losses can be overcome, nor the collisional dumping of energy from the ions to the electrons.
The loses are overcome by using an open, recirculating design. Electrons get out the cusps, and are drawn back in by holding the magnetic coils at a high positive potential. The cusps just need to make the electron density sufficiently higher inside than outside. The outside electrons need a low enough density that they don't arc out. The internal electrons need a high enough density to accelerate ions to fusion speeds. A simple enough design, but Bussard's team wasted a long time trying to design a closed mirroring version which they later demonstrated could never achieve low enough loses. A big reason for testing with non-recirculating designs was the easier engineering since they're budget was so small.
Plus, the design team originally modeled all the coils with as a zero thickness circle and couldn't understand that when they built the thing that the coil circle centers had to be spaced apart which caused field losses. After seeing stupid design errors like that, I don't have much faith in the research team, but still the concept is worth investigation.
Actually, they initially designed it with permanent magnets and drove the electrons right into the magnets themselves. But the point was to prove electron densities in the center could get high enough for fusion. Regardless of the mistakes made along the way, the got the concept to work for their final tests and expect some big results from the new WB-7 some time next year.
The catch to these devises appears to be that if you have a strong enough electrostatic field to contain the ions then you will also lose A LOT of high energy electrons (Rider 1995)
And Bussard insisted that Rider's math model was flat out wrong. Recent experiments by Yoshikawa and MIT have both demonstrated that Rider's model is, in fact, wrong.
The Polywell design has tremendous merit to it and the experiments that Bussard managed at the end of his life were successful in measuring fusion scaling factors and electron loss factors. From those experimental results Bussard's team rushed together what was expected to be their last device in WB-6. On analyzing the data it generated, it achieved record breaking fusion rates. Now that the navy has re-funded his team to finish WB-7, expect to see some big announcements in a year or so.
For more on Polywell theory and background go here.
Seriously though, weren't there likely alternatives at the time? DDT was possibly a cheaper and/or better marketed solution,
One of the biggest deployments was by the allies at the end of WW2. Dis-infecting prison camp survivors with a DDT dusting was part of the process at medical tents. When you talk big scale deployment cheaper saves lives, it was not about maximizing profit. Similarly DDT usage to hold back malaria in Africa through the 50's and 60's saved lives. Even counting the lives lost to the unforeseen poisoning of the environment, the DDT program saved lots of lives.
A solution needn't be perfect, just better than the alternatives. Thankfully we've got better chemicals for much of this now. Similarly, GM crops may eventually reduce chemical use in agriculture. If it could accomplish that, it might be step up from current methods environmentally speaking.