15th US-Japan Workshop on IECF

[crowberry]

The 15th US-Japan Workshop on Inertial Electrostatic Confinement Fusion
will be held in Kyoto, Japan October 6-9, 2013. The website is here
http://www.iae.kyoto-u.ac.jp/beam/iec2013/
but there is not yet much content.

[ladajo]

Initial Participants list should be posted today.
I fully expect Joel Rogers to show again.

Thanks for finding the site crowberry.

[crowberry]

The initial list of participants has been published on the website.
http://www.iae.kyoto-u.ac.jp/beam/iec20 ... pants.html

[crowberry]

The programme is posted now on the website. There are at least two Polywell talks:
4-2 "New Design Features for Polywell", Joel G. Rogers, Convergent Scientific, Inc.
5-2 "Capacitive Probe for Plasma Potential Measurements in a Vacuum diode and Polywell Device", Scott J. Cornish, The University of Sydney

[DeltaV]

2-3 "Towards a Virtual Cathode for Inertial Electrostatic Confinement Fusion", Joe Khachan, The University of Sydney

[ladajo]

I am interested in the SiC talk by the Kurita Corp. guy. Seems a little out of field for them.

[crowberry]

The talks are now up on the website at http://www.iae.kyoto-u.ac.jp/beam/iec2013/program.html.
There is lots of interesting stuff there.

[ladajo]

Thanks, I was wondering about that recently.

[mvanwink5]

This was an interesting paper by Joel Rogers and compares Lockheed's T4, which is postulated as a spindle cusp IEC machine, to a polywell machine. The paper also looks at a 3T superconducting poywell.
http://www.iae.kyoto-u.ac.jp/beam/iec20 ... on/4-2.pdf

Abstract
New design features include a differentially pumped ion source and an electron extractor. Differential pumping localizes the ion birthplace to be at the peak of the electrostatic potential, thus minimizing the ions' energy spread. The electron extractor localizes up-scattered electron losses to occur only in one selected point cusp, thus improving the reactor power balance and the accuracy of simulation. Two-dimensional PIC simulation was used to investigate the scaling of the power-balance with magnet size. Both a two-magnet spindle-cusp design and a six-magnet Polywell design were simulated with D+D fuel. The Polywell design demonstrated much superior power balance compared to the spindle cusp. Even so, scaling to break-even leads to an impractically large reactor size. Thus, it now appears that resistive magnets will not work with advanced fuels. Super-conducting magnets will be required to reach break- even. Simulation also suggested favorable bremsstrahlung scaling with size. This gives hope for future reactor designs utilizing p+B11 fuel.

[Skipjack]

Yeah, overall the articles did not look too good for polywell
Scaling seems to be less favorable than originally anticipated.

[DeltaV]

1) L-M is probably using a 3-coil "synthetic FRC" as pointed out by Torulf, not the discussed 2-coil design.
viewtopic.php?f=10&t=5010

2) The Aussie test Polywell pictured neglects proper magrid coil spacing and rounding.

[mvanwink5]

We already knew Joel Roger's simulation output predicted a very large break even polywell diameter, but PIC code is no substitute for WB-8 data. Also, remember Joel had an earlier and more pessimistic model than his current one, so who knows what his next generation model will show? Furthermore, we have had some inference from the Navy's' sole source memo on scaling earlier this year that seemed to suggest a positive picture. I just appreciate that effort other than EMC2 funded by the Navy is being done. However, those are just my thoughts.

[D Tibbets]

1) L-M is probably using a 3-coil "synthetic FRC" as pointed out by Torulf, not the discussed 2-coil design.
viewtopic.php?f=10&t=5010 ....

The picture through the window certainly does not show a biconic cusp. The plasma is all wrong for this. While I do admit that a smaller central magnet (of three) may be a FRC set up. I do not believe the plasma glow is consistent with this. As I have seen with my permanent magnet arrangements, three magnets of similar diameter, or with a larger diameter central magnet does give a plasma glow appearance consistant with what is shown in the picture. This is basically a variation on the Polywell, except a polyhedron is not used. Instead the central magnet splits the equatorial line cusp of a biconic mirror arrangement into two much narrower line cusps.This is actually what a Polywell polyhedral arrangement does except the "central magnet" is an assembly of four separate magnets (in the truncated cube example) that distorts the two line cusps into a complex geometry. The central null field and symmetry is maintained in both examples. The biggest difference other than possible differences in net line cusp containment efficiency (average width * length) is two fold. In the cylindrical three opposing magnet arrangement there are two line cusps and two point cusps. In the truncated cube Polywell there are two deformed line cusps and 6 point cusps. I speculate that the three magnet arrangement may have net better confinement mostly due to the decreased point cusps. How this compares to the confined volume though is uncertain. The whole point of the Polywell concept is to improve mirror confinement in a way similar to moving the magnets closer together- thus narrowing the width of the line cusp, but of supreme importance is doing so while retaining the original equal aspect opposing magnet biconic cusp machines internal reaction volume. And of course, because of the improved confinement efficiency per unit of volume, allowing for practical electron currents leading to yet increased volume and better confinement simultaneously (Wiffleball effect).

Dan Tibbets

[DeltaV]

Instead the central magnet splits the equatorial line cusp of a biconic mirror arrangement into two much narrower line cusps.

You mean into two point cusps, don't you? The two cusps in Torulf's drawing are colinear "lines" along the escape routes that perpendicularly intersect a control volume's surface at only two points.

[Torulf2]

The two line cusps are connected and recycle particles.
Its only two point cusps there they can escape.