any new developments in the last month?

What are the problems you’re facing now and how is your timetable for this year?

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We found that no significant difference in the ratio of the NTF to FTF signals occurred because of the filter. The x-rays were acting as if the 3 mm copper was transparent. 

This could only be the case if the x-rays were produced by electrons that had an average energy of at least 400 keV. We will keen to analyze in even greater detail results relative to the electron temperature, which is crucial for in turn heating the ions and thus overall fusion yield.

The LPP effort is focusing, of necessity, on showing neutron production. This is technically challenging and expensive.

Could some of the important sub-problems be usefully ‘farmed out’ to be experimentally attacked in parallel efforts using cheaper, less challenging experimental setups? I am thinking cheaper because these ‘dummy’ fusors would use lower voltage, less finicky vacuum and gas requirements, and since they would be incapable of producing neutrons, there would be no need for neutron measurement hardware.

This idea is dependent on developing sensors to serve as ‘goodness’ indicators in the absence of neutron production. For example, coils might be able to detect the current and arrival time of each of the arc filaments (perhaps at the exit of the outer annulus where the filaments start their 180 degree turn) as an indicator of plasma symmetry. Perhaps symmetry sensors adjacent to the pinch region (UV, magnetic, or resulting plasma jet current?) could be useful.  If such sensors could be made, then it might be possible to cheaply investigate in parallel a lot of ideas that are now wildly impractical to test on the LPP neutron producing device.

Sub-problems that could be investigated include:

Arc filament symmetry and other characteristics in terms of minor hardware geometry or external field variations.
Metal erosion problems (wear such as pitting) in terms of effects on arc filament symmetry.
High repetition rate effects, including localized heating at erosion pits, on arc filament symmetry,

Solutions that could be investigated include:

Highest priority – New instrumentation applicable to both 1) the LPP fusor for continuously diagnosing asymmetry problems (sensors for the current and arrival time of each of the sixteen arc filaments and perhaps new sensors for the pinch region?) and 2) critical to the ‘dummy’ fusor test effort, sensors to serve as the ‘goodness’ indicators of testing in the absence of neutron production.

Secondary priorities –
Whatever people can think of
Big geometry variations

EDIT 11-30-2011 It has been a couple of days with no responses. I’ll change what I am asking.

If there were separate parallel experimental efforts using less challenging test setups as described above to work on sub-problems, what design space variations would you like to see? (Less challenging test setups at lower voltages, simpler geometries, and no possibility of neutron production would be within the capability of any university physics program and perhaps some advanced amateurs.)

Tulse on another thread suggested:

1) “A solid piece (cathode), with projections to guide the plasma filaments, would mean that one never had to worry about individual cathode alignment.”

I am interested in

2) the capability of heated surfaces (naturally heated in a fast repetition device) to reduce pitting and erosion typical of cold electrodes

3) the possibility of active control of each arc filament to maintain symmetry at the exit of the outer annulus.

Any other suggestions for a wish list?

——-
To achieve nuclear fusion for practical energy production, scientists often use magnetic fields to confine plasma. This creates a magnetic (or more precisely “magneto-hydrodynamic”) fluid in which plasma is tied to magnetic field lines, and where regions of plasma can be isolated and heated to very high temperatures—typically 10 times hotter than the core of the sun! At these temperatures the plasma is nearly superconducting, and the magnetic field becomes tightly linked to the plasma, able to provide the strong force needed to hold in the hot fusion core. The overall plasma and magnetic field structure becomes akin to that of an onion, where magnetic field lines describe surfaces like the layers in the onion. While heat can be transported readily within the layers, conduction between layers is far more limited, making the core much hotter than the edge.
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http://www.physorg.com/news/2011-11-plasma-confinement.html

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A major upgrade to the DIII-D tokamak fusion reactor operated by General Atomics in San Diego will enable it to develop fusion plasmas that can burn indefinitely. Researchers installed a movable, 30-ton particle-beam heating system that drives electric current over a broad cross section of the magnetically confined plasma inside the reactor’s vacuum vessel. Precise aiming of this beamline allows scientists to vary the spatial distribution of the plasma current to maintain optimal conditions for sustaining the high temperature plasmas needed for fusion energy production.
——-
http://www.physorg.com/news/2011-11-plasma-confinement.html

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A fusion reactor operates best when the hot plasma inside it consists only of fusion fuel (hydrogen’s heavy isotopes, deuterium and tritium), much as a car runs best with a clean engine. But fusion fuel reactions at the heart of magnetic fusion reactors also create leftovers—helium “ash.” The buildup of this helium ash and other impurities can cool the hot plasma and reduce fusion power. Research at the MIT Plasma Science and Fusion Center is providing new insight into the transport of these impurities in fusion plasmas in an effort to improve on the natural impurity exhaust process, producing cleaner plasmas and higher fusion power.
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http://www.physorg.com/news/2011-11-tokamak-impurity.html

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Experiments discover a 3-D process by which magnetic reconnection can release energyfaster than expected by classical theories.
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The article is here,
http://www.physorg.com/news/2011-11-d-magnetic-energy-fast.html

what is the maximum magnetic field strength already achieved by FoFu-1, during any pinch?

I posted this question (below) as a comment against the post at http://www.lawrencevilleplasmaphysics.com/index.php?view=entry&year=2011&month=10&day=19&id=48:new-record-fusion-yields-as-fofu-1-shows-rapid-scaling&option=com_lyftenbloggie&Itemid=90 a couple of days ago, then thought it would have been better posted here first (a feeling confirmed by the fact its just now been ‘removed’ from the comments on the other site)

My question was (from memory):

{ “rcain”::}

i wonder is there any (detailled) response to the apparent ‘saturation’ limits to theoretical scaling law, due to ‘axial phase dynamic resistance’ factor, as described in this recent paper:

http://www.mdpi.com/1996-1073/3/4/711/

{” http://www.mdpi.com/1996-1073/3/4/ “::}
...
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.
...

(they are not totally pessimistic about the future of the DPF approach.)

i managed to find out in this forum that Eric Lerner is certainly aware of this work and the ‘dynamic resistance’, but it didn’t give away many details,

He made a short response on the FoFu forum last year ( http://focusfusion.org/index.php/forums/viewthread/746/P15 -  22 November 2010) :

{“Lerner”::}
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.

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).

can anyone offer any further elucidation?

thanks (and apologies if i’ve inadvertently breached etiquette on my other post - but the comment button suggested i was invited to ask).