Unfortunately they haven't yet matched the output of the PF1000 machine, and haven't moved beyond the known scaling laws or saturation limits.
http://www.mdpi.com/1996-1073/3/4/711/
I applaud their open approach, but it is hard to see where the required breakthrough is going to come from - the above paper outlines the problems they face in progressing any further.
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very interesting paper - thanks RobL - i haven't read it all yet - very detailed treatment.RobL wrote:Unfortunately they haven't yet matched the output of the PF1000 machine, and haven't moved beyond the known scaling laws or saturation limits.
http://www.mdpi.com/1996-1073/3/4/711/
I applaud their open approach, but it is hard to see where the required breakthrough is going to come from - the above paper outlines the problems they face in progressing any further.
Would be very interested in getting Eric Lerner's response to its findings. Maybe I'll post something on his site/forum.
PS. they seem to be in same ballpark - ie. > 10^11 neutrons per shot.
The paper is interesting indeed, it did not prove anything for lack of data, but it raised a series of interesting points.
I think this issue will cleared pretty quickly by Dr. Lerner and his team, they are in the same ballpark as rcain correctly pointed out.
Whatever the result will be this is good science and well spent money
I think this issue will cleared pretty quickly by Dr. Lerner and his team, they are in the same ballpark as rcain correctly pointed out.
Whatever the result will be this is good science and well spent money
hmm, here is how they describe their main conclusions:
so they are not totally pessimistic about the future of the DPF approach.http://www.mdpi.com/1996-1073/3/4/ wrote: ...
A global scaling law for neutron yield as a function of storage
energy was uncovered combining experimental and extensive numerical data, showing that scaling deterioration has been wrongly interpreted as neutron ‘saturation’. However in keeping with conventional terminology, the effect of scaling deterioration will continue to be referred to as neutron
‘saturation’. The cause of neutron ‘saturation’ as device storage energy is increased was found to be the axial phase ‘dynamic resistance’. With the fundamental cause discovered, it is suggested that beyond ‘present saturation’ regimes may be reached by going to higher voltages, and using plasma current enhancement techniques such as current-steps.
...
I think going to higher voltages is one of LLP's main goals. The density of the plasmoid and duration (?) is also possibly enhanced due to the addition of angular momentum.
Are any of LLP's results included in their modeling? The graph is hard to read with logarithmic scales. but with the x-and y scales appearing to be near matched. The graph shows a trend (even before 'neutron saturation' sets in (slope starts flattening))of neutron yields vs current. For a 1000 fold increase in current, there is a ~ 10,000 fold increase in neutrons. this would represent a scaling of well below the second power of the current. This is far different than the LLP claim of scaling at the 5th power, even at these lower energies.
That saturation sets in may be an accepted trend, as DPF devices are thought to be limited to a few million Joules. I don't know whether this is due to this saturation or if it is due to technical issues. The bone of contention may be the slope of the graph before saturation sets in. The note that the ~ 10^11 yields at a few hundred thousand Joules does match the graph though.
Dan Tibbets
Are any of LLP's results included in their modeling? The graph is hard to read with logarithmic scales. but with the x-and y scales appearing to be near matched. The graph shows a trend (even before 'neutron saturation' sets in (slope starts flattening))of neutron yields vs current. For a 1000 fold increase in current, there is a ~ 10,000 fold increase in neutrons. this would represent a scaling of well below the second power of the current. This is far different than the LLP claim of scaling at the 5th power, even at these lower energies.
That saturation sets in may be an accepted trend, as DPF devices are thought to be limited to a few million Joules. I don't know whether this is due to this saturation or if it is due to technical issues. The bone of contention may be the slope of the graph before saturation sets in. The note that the ~ 10^11 yields at a few hundred thousand Joules does match the graph though.
Dan Tibbets
To error is human... and I'm very human.
Eric Lerner is certainly aware of this work and the 'saturation' (/'dynamic resistance') phenomenon that deteriorates scaling law.
He made a short response on the FoFu forum last year ( http://focusfusion.org/index.php/forums ... ad/746/P15 - 22 November 2010) :
Dan - re power law - I think the I^4.6 relates to total energy out rather than simple neutron out count.
anyway' ive posted up a question on their news board.
He made a short response on the FoFu forum last year ( http://focusfusion.org/index.php/forums ... ad/746/P15 - 22 November 2010) :
consensus on that forum seems to be that a voltage of around 90kV should 'break the barrier' - which, since it is expensive to rig for, Lerner is only prepared to do once all other feasibility questions have been resolved (as per his response above).Lerner wrote: Right now, we think that we will get to a demonstration of feasibility at around 2.8 MA, which is below Lee’s limit. Going much beyond our planned 45 kV will involve significant changes to the facility—power supply, capacitors, insulation, etc. Of course, as a practical matter, if we got very close and were on a rising curve, we should be able to stop and make major changes to increase voltage. Hopefully, that won’t be needed.
Dan - re power law - I think the I^4.6 relates to total energy out rather than simple neutron out count.
anyway' ive posted up a question on their news board.
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Joseph Chikva
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Dan, you missed.D Tibbets wrote:For a 1000 fold increase in current, there is a ~ 10,000 fold increase in neutrons.
They are not going to increase the current 1000 fold for device right now producing megaamperes.
But they have a talk about following scaling: neutron yield proportional to I^4.6 (almost 5)
So, for a 10 fold increase in current, expected neutron yield would increase 100,000 times.
But what this will give?
10^11 of neutron yield per a single shot for D-T reaction (14.1MeV) makes 0.2256J
So, for a 10 fold increasing in current, they will earn 22.56kJ
As I have read from above quoted paper DF1000 device in Warsaw has 1MJ capacitor bank. I think that Lerner's team also operate with tens and may be hundreds kJ capacity of pulse energy storage.
Joseph Chikva, I did my estimate by extracting the numbers from the graph presented with the referenced article abstract, not Eric Learners quotes. From a current increase from ~ 500 to 500,00 thousand Joules, the Neutron output (or the total output which I assume would be neutron output + KE of the produced P, tritium, and He3, and bremsstrulung(?)) only slowly.. This gave a scaling of ~ 1.8, and I contrasted this with Learner's claimed (and demonstrated?) scaling of nearly the 5th power. Thus the issue of reaching breakeven before 'neutron saturation' is completely different, based on which scaling law is applied.
From subsequent comment, it seems that Learner is cautiously optimistic that this effect is not critical, and if it turns out to be critical he has a possible work around. Like some criticisms of Bussard's Polywell, Potential road blocks may not yet been cleared, but claiming that they have not at least been recognized is invalid.
Dan Tibbets
From subsequent comment, it seems that Learner is cautiously optimistic that this effect is not critical, and if it turns out to be critical he has a possible work around. Like some criticisms of Bussard's Polywell, Potential road blocks may not yet been cleared, but claiming that they have not at least been recognized is invalid.
Dan Tibbets
To error is human... and I'm very human.
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Joseph Chikva
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Dan, current's unit is Ampere and not Joule. Energy stored in capacitor = CU^2/2, where C-capacitance, U - voltageD Tibbets wrote:Joseph Chikva, I did my estimate by extracting the numbers from the graph presented with the referenced article abstract, not Eric Learners quotes. From a current increase from ~ 500 to 500,00 thousand Joules, the Neutron output (or the total output which I assume would be neutron output + KE of the produced P, tritium, and He3, and bremsstrulung(?)) only slowly.. This gave a scaling of ~ 1.8, and I contrasted this with Learner's claimed (and demonstrated?) scaling of nearly the 5th power. Thus the issue of reaching breakeven before 'neutron saturation' is completely different, based on which scaling law is applied.
From subsequent comment, it seems that Learner is cautiously optimistic that this effect is not critical, and if it turns out to be critical he has a possible work around. Like some criticisms of Bussard's Polywell, Potential road blocks may not yet been cleared, but claiming that they have not at least been recognized is invalid.
Dan Tibbets
If they have saturation of energy - yieald does not increase by increasing of energy, I assume geometric dimension would limit energy.
And if at the same time they have so attractive relation between yield and current, the scaling seems to me as following: to increase dimensions for increasing input energy limit and to increase discharge voltage.
As current is function (generally non-linear) of voltage.
Here again the problem of anode erosion would arise at higher voltage.
yes sounds to me like they are heading into a more difficult time, possibly. my guess is Eric Lerner has his fingers crossed and will 'tackle' the 'saturation' bridge when he comes to it:Joseph Chikva wrote:Dan, current's unit is Ampere and not Joule. Energy stored in capacitor = CU^2/2, where C-capacitance, U - voltageD Tibbets wrote:Joseph Chikva, I did my estimate by extracting the numbers from the graph presented with the referenced article abstract, not Eric Learners quotes. From a current increase from ~ 500 to 500,00 thousand Joules, the Neutron output (or the total output which I assume would be neutron output + KE of the produced P, tritium, and He3, and bremsstrulung(?)) only slowly.. This gave a scaling of ~ 1.8, and I contrasted this with Learner's claimed (and demonstrated?) scaling of nearly the 5th power. Thus the issue of reaching breakeven before 'neutron saturation' is completely different, based on which scaling law is applied.
From subsequent comment, it seems that Learner is cautiously optimistic that this effect is not critical, and if it turns out to be critical he has a possible work around. Like some criticisms of Bussard's Polywell, Potential road blocks may not yet been cleared, but claiming that they have not at least been recognized is invalid.
Dan Tibbets
If they have saturation of energy - yieald does not increase by increasing of energy, I assume geometric dimension would limit energy.
And if at the same time they have so attractive relation between yield and current, the scaling seems to me as following: to increase dimensions for increasing input energy limit and to increase discharge voltage.
As current is function (generally non-linear) of voltage.
Here again the problem of anode erosion would arise at higher voltage.
...see if he cant pull a factor of a few hundred out of he that somewhere, without everything vaporizing and putting California's lights out.
making it 'bigger' seems to be generally a 'less successful' strategy, if i read FoFu's recent blog entries on other collaborative/independent experiments correctly.
from what i remember of that paper, there's still a big factor of Imax to Ipinch conversion to be gained/recovered into-process, possibly. (but i think he's been exploiting that to date, ,already).
it will be interesting to see whether Lerner, ramps up his Hard-Xray commercial product spin off, any time soon.
i'm still trying to raise some response to the original question on their blog/forum.
There's a new story up: 2011 Year in Review. It has a link to the December newsletter, which is on Constant Contact, and which itself contains the link to the December report. Direct link is here.
The December report focuses primarily on the axial field coil (AFC) and its usefulness in producing X-rays. So things are looking promising for the X-Scan spin-off application, at least. Also, LPP has compiled a data archive of its first two years of experimentation on FF-1, which has allowed for easier comparison of data between various shots. Analysis of data from the near and far time-of-flight detectors in a series of over 30 shots between late September and early October of 2011 has revealed that FF-1 consistently produced electrons with an average energy of over 400 keV.
I think that's basically it, apart from a promise that the density of the gas will be increased in future experiments (no timetable given), which should lead to an increase in fusion yield, and to the effect of the axial field coil on the fusion yield.
The December report focuses primarily on the axial field coil (AFC) and its usefulness in producing X-rays. So things are looking promising for the X-Scan spin-off application, at least. Also, LPP has compiled a data archive of its first two years of experimentation on FF-1, which has allowed for easier comparison of data between various shots. Analysis of data from the near and far time-of-flight detectors in a series of over 30 shots between late September and early October of 2011 has revealed that FF-1 consistently produced electrons with an average energy of over 400 keV.
I think that's basically it, apart from a promise that the density of the gas will be increased in future experiments (no timetable given), which should lead to an increase in fusion yield, and to the effect of the axial field coil on the fusion yield.
Temperature, density, confinement time: pick any two.
There's a new update up, in two parts:
2011 achievements and goals for 2012
Understand the focus fusion energy flow
Not a whole lot of news, but the first update mentions "initial shots at 45 kV (full voltage)", although it doesn't say when that happened, exactly. It's probably worth quoting here LPP's goals for 2012:
2011 achievements and goals for 2012
Understand the focus fusion energy flow
Not a whole lot of news, but the first update mentions "initial shots at 45 kV (full voltage)", although it doesn't say when that happened, exactly. It's probably worth quoting here LPP's goals for 2012:
1. Demonstrating the theoretically predicted fusion yield with pure deuterium.
2. Showing higher fusion yield with heavier gas mixtures.
3. Achieving reliable performance at still higher fill pressures.
4. Boosting yield even further with shorter electrodes, which allow higher gas densities.
5. Achieving giga-gauss magnetic fields in the plasmoids.
6. Demonstrating the quantum magnetic field effect’s reduction in X-ray cooling
7. Demonstrating scientific feasibility with pB11 fuel.
Temperature, density, confinement time: pick any two.