A new (?) paper on a sorta- Polywell concept.

Discuss how polywell fusion works; share theoretical questions and answers.

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DeltaV
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Postby DeltaV » Fri Apr 23, 2010 7:59 pm

jrvz wrote: Very interesting. I'm not sure I understand the two concentric layers of coils. Do they plan to use the outer coils to induce currents in the inner coils (mirror currents)?
Maybe just one layer is too leaky. They already have supports that can contain the power cables.

jrvz wrote:They don't mention putting the coils at some electric potential (i.e. implementing a magrid).
Indeed, not the IEC approach.
This confinement configuration involves electron cyclotron resonance heating with the use of a pair of very high frequency (~200 GHz) gyrotrons along with a very strong magnetic field (~7.2 T)...

jrvz wrote:I think this coaxial coil geometry does offer one advantage over the polywell. Both have line cusps. For the polywell, the peak field varies along the cusp, so I expect the leakage to be largest where the cusp is furthest from the coils. If the field is just strong enough there, then it's stronger than necessary everywhere else. For the coaxial geometry, the peak field is the same all along a given cusp. Looks more efficient.
But one might also argue that because Polywell's field near the nubs is so high, there are effectively no line cusps, just 14 point cusps.

While in no way proof, the picture on EMC2's web site hints at point cusps at the cube corners, not line cusps between coils. Note the faint jets in the corners on the right side of this picture and the "sparklies" at what looks like the base of the jets on the left side (just inside the top and bottom of the face-on coil):

Image

rcain
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Postby rcain » Fri Apr 23, 2010 10:22 pm

DeltaV wrote:
jrvz wrote: ..They don't mention putting the coils at some electric potential (i.e. implementing a magrid).
Indeed, not the IEC approach....


seems electrons injected form space charge to that same effect. i believe use of charged magrid as in Polywell would amplify the containment effect they are studying here, which they claim is in itself capable of required fusion conditions.

some graphs here of related work - http://www.iccworkshops.org/icc2010/upl ... poster.pdf (...you'll need to enlarge it).

also uncertain as to magnitudes of combined magnetic fields of inner and outer spheres, ie. why the outer? they talk about large containment/vacuum vesel, so perhaps something to do with recirculation efficiency, or cavity impedance/Q perhaps?

nice to see this is current research though. lets hope for some published papers soon.

vernes
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Postby vernes » Mon Apr 26, 2010 12:28 pm

A quick search around the net tells me "BUDAEV Viatcheslav" hasn't touched the subject of 'Inertial Electromagnetic Confinement' ever since.

I was hoping for some actual photo's of the setup.

rcain
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Postby rcain » Mon Apr 26, 2010 5:17 pm

... perhaps he had to get a proper job.

some photo's of a (related) 'small experiment' here - http://www.iccworkshops.org/icc2010/upl ... design.pdf

looks to me like perhaps Nebel and Lerner in particular might have sparked off a bit of a resurgence in alt-fusion studies.

jrvz
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Postby jrvz » Thu Apr 29, 2010 4:33 pm

DeltaV wrote:That sounds right. That's a higher coil density than his Figs. 1 & 2, which have coils at 0, 30, 60, 90 deg.

Field lines topology for spherical system of 5 ring cusps and point cusps at the axes is shown in Fig. 2. It illustrates the minimum-B configuration that offers a good magnetohydrodynamical stability.


On further study, it's a little more complicated than that. There seem to be pairs of coils (AKA "ring cusps") at latitudes -60, -30, 0, 30, and 60, plus single coils ("point cusps") near +-90. Each coil has a near neighbor and a more distant neighbor. Its current direction is the same as the distant neighbor*, and opposite its near neighbor, so the cusps are between near neighbors. It's a way of increasing the field strength of the cusps (reducing leakage) without having to create high fields everywhere. Economical.

* with one exception, so that the end coils have the same polarity. I don't see why.
- Jim Van Zandt


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