February 01, 2009

Update on IEC Fusion




The Talk Polywell has been analyzing the latest Navy project for the Inertial Electrostatic (Bussard/IEC) fusion effort.

* The contractor will modify/upgrade the existing wiffleball #7 (WB-7) device by installing compact, high temperature coil joints to investigate the electron parallel heat loss. This modified device shall hereafter be identified as Wiffleball #7.1 (WB-7.1).

* The Contractor shall test the WB-7.1 to measure the plasma beta (ratio of plasma pressure to the applied magnetic field pressure) and to monitor the wiffleball formation process. The contractor will deploy multiple magnetic field probes inside the device to generate time varying magnetic field mapping to investigate the wiffleball formation.

* The contractor shall take the results of the review specified in 3.1 and tests specified in 3.2 and provide a report detailing workable instrumentation set-ups to resolve the plasma production and physics questions raised in the review and tests for a final report for contracts.


Dan Tibbets:
Bussard mentioned these joints in his Google talk and said they could be shielded. How that would be done is open to debate. I would guess that a charge wouldn't help due to that old - no effective electrostatic field inside a hollow sphere argument. And, I don't see how a magnetic field associated with the small number of wires that could be packed inside these much smaller interconnects could magnetically shield as well as the thicker magnetic grid. The suggestion of mounting each coil on ceramic standoffs that are in the 'shadow' of the grid seams reasonable to me- if recirculation is mostly oscillation or bouncing within a single cusp, rather than orbiting through another cusp. If burning p-B11 these supports could possibly also serve as mounts for the energy capturing deceleration grids.


Tom Ligon:
From my first read thru the Valencia report, I thought the nubs would have to go. If the coils must be spaced to avoid the funny cusp, I just instinctively felt the nubs must be a loss path. They may be orders of magnitude less so than the old geometry, but I felt they would bleed off high-energy electrons.

I wanted them to try ceramic support of the coils individually from outside the chamber from that moment. This also has the benefit of allowing individual coils to be replaced, and of allowing better cooling mechanisms where copper-coil machines are used. In fact, when we started considering the very first water-cooled copper machines, I wanted to use that approach.


The 7.1 Wiffle Contract is a cost plus contract that could go until Dec 31, 2009. Eleven months was similar to the duration of the last nearly 2 million effort to build version 7.0. Therefore, this cost plus work could run nearly
$2 million.

M Simon suggests next steps for development:

1. A pulsed small superconducting version. If a lot of neutrons (1E12/sq cm Second) were not generated (or only generated in pulses) MgB would be a good candidate for the coil material if the coils were totally custom. Buy an MRI machine for the superconducting coils. An MRI can be had for about $1 million. The superconducting coils might only be $200K. A WB machine built like that could be done for probably $5 to $7 million. If it shows good pulsed results then buy power supplies for a continuous operation experiment.

2. A continuous operation experiment (liquid nitrogen cooled copper magnet coils described as a WB-7x Design) could reach .45 Tesla magnetic field strength for about $20 million. Most of that going into power supplies. That is a rough estimate: +/- $5 million is probably 1 sigma.

3. A full scale net energy Polywell Fusion proof of all concepts program would cost $200 million.



Peswiki has some information from Bussard before his death and Roger Fox.

Bussard:
Inertial Electrostatic fusion can make power at about 5/8 the cost of conventional plants (most is BOP, Balance of Plant costs) process steam at 1/3 the cost of others, make synfuels (ethanol) at less than $0.5/gallon, destroy nuclear waste, and make space engines commercial, etc, etc. The basic physics is summarized in Bussards IAC paper in October, 2006. And in much earlier papers in the early 1990's. All still valid.


Roger Fox points out:
1) Dr Bussard has used DD fuels, not P-B11. His results do indicate P-B11 fusion can occur in a small device such as WB-6, with a high enough drive level.
2) Fuel ions are generally not confined by the McGrid or magnetic fields. Fuel ions are accelerated by the potential well. Fuel ions' behavior is generally dictated by the breadth & depth of the potential well
3) Bussard states that 200 million and about 5 yrs can yield a proof of concept, not a prototype.
4) A D-D fueled polywell of net power size would likely use heat/steam much as current fission plants do to generate electricity.
5) A P-B11 fueled Polywell of net power size would use electrostaic grids to trap alphas, to generate electricity.
6) WB-6 was a cube as was the WB-7 version.
To get to He, lIRC there is some fission. The Carbon 12 must split, as well as the Be.
7) P-B11 fusion is aneutronic, meaning it creates no neutrons. That is not to say there is no radioactivity.


8) Cusp loss effects: electrons recirculate many thousands of times. Dr Bussard has inferred that the truncated cube or dodecahedron may improve electron loss figures & general efficiencies by 3 to 5 times. As is, since electrons recirculate, this is a minor issue.
Liquid nitrogen cooling would allow for 100's of seconds of run time vs the millisecond pulses that WB-6 performed.

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