Talk-Polywell.org

LPP Chief Scientist Eric Lerner is on Reddit for an Ask Me Anything Q&A session, July 3rd 2014, from 3pm to 5pm EDT.
He will answer various questions especially about the crowd-funding effort on IndieGoGo, launched to build a beryllium electrode for the Dense Plasma Focus.

The Q&A is on the subreddit /r/IAmA/
UPDATE: It's on http://www.reddit.com/r/IAmA/comments/29ri37/focus_fusion_energy_with_eric_lerner_ama/

He's been talking about that Beryllium electrode since I talked with him back in 2005. What's the deal that it's so difficult?

Apparently they simply don't have the money. From their web site:

To demonstrate that focus fusion works we are installing tungsten electrodes in May and expect a big boost in energy output. Tungsten is fine for impurity, but absorbs too many x-rays, so we need beryllium electrodes next to achieve our goals. It’s expensive—we need $250,000 for them—what we are crowdfunding to raise.

It's a pity they need to ask people to get a few hundred thousand dollars where others similar companies got tens of millions (EMC2) and even a hundred million (Tri Alpha) through contracts with government agencies and VC.

Calculated benefits from Beryllium electrodes (excerpt from this page):

Rate of aneutronic reactions: 7×10^18/s

Secondary neutrons per aneutronic reaction (our calculation—some other estimates are as low as 1/1000): 1/200

Proportion of neutrons absorbed by Be9 electrode to produce Be10 (cross section 0.1 mbarns; average depth of Be 1 cm): 1/75,000

Rate of Production of Be10 nuclei: 4.7×10^11/s

Total Be10 nuclei produce in 1 month: 1.2×10^18

Rate of decay of this many Be10 nuclei (Be10 half life 1.4My): 2.9×10^4 decay/s

Equals 0.8 micro curies of radioactivity in each used set of electrodes.
Radioactivity of human child –about 0.2 micro curies
Radioactivity of classroom of 25 children—5 micro curies
This is why we won’t need to worry about the radioactivity of the Be electrodes before they are recycled.

The benefits of the beryllium electrode has nothing to do with radioactive decay. It is nice if the induced radiation from a modest neutron bombardment is easily managed, but the benefit has to do with X-rays.
The bremsstruhlung x-rays generate a relative large dose of x-rays and much of this radiation passes through the electrodes. The absorption of the x- rays creates a lot of heat over a small area. The electrode literally melts. The advantage of beryllium is that it tolerates a lot of heat and because of it's small atomic weight, most of the high energy x-rays pass through the electrode without depositing any heat. This would be much different in another tough/ hard and high melting temp. metal like tungsten. Lithium would be even better from an X-ray transparency perspective, but it has a low melting temperature, and would produce tritium with neutron bombardment.

Dan Tibbets

Hello Talk-Polywell! My first reply after much read-only access, and it is of course a begging letter..!

LPP are close to both their target for funding, and the end of their indiegogo campaign - ends midnight today July 5th.

https://www.indiegogo.com/projects/focu ... heworld--3

For me, the benefit of supporting this research is clear: the sums involved are so small, and the potential benefits of success so large, that even a trivial probability of success makes for a very high cost-benefit ratio. Society needs this research funded!

I thought it was at least worth a sum of money I wouldn't miss. It won't take many more donations to get them over the line.