Another one from Alan Boyle

[bcglorf]

When talking about neutron counts and if Nebel's comments imply they are matching Bussard's last run I look at this quote: "The answers are going to be kind of nuanced,". I'm not sure, but I'd have thought re-creating the neutron counts from WB-6 wouldn't have been nuanced, they'd be compelling. I'm still crossing my fingers but my wild guess is the results are some place a bit short of the WB-6 final results.

[rj40]

bcglorf,

Yes, that is what I was thinking too. I hope it is enough though, I would like to see a full-up demo of net power.

[rj40]

A full-up working demo built that is. I realize the WB-7 isn't designed to do net power.

[MSimon]

He may not be looking for neutrons. The focus may be on confinement.

Note that he seems to be working with He4 and not D-D. Same e/m (within the required limits) and no neutrons to worry about. All you need to worry about then is measuring current/voltages/light pulse in real time to see what the B=1 (for magnetic field e confinement) looks like.

Change the pulse voltage (e-field). Change the pulse current (B-field). Change the electron injection profile (beam I). And you can explore the surface. Look for the light flash when the electrons are no longer confined. (can be timed to nS with photomultipliers).

[tonybarry]

Dr. Joe Khachan seemed to think that the acid test for the polywell would be confinement; and best measured with a microwave interferometer. I sent Joe the Alan Boyle link, and he replied as follows:-

"... Thanks for the link on Rick's interview. Looks like he is happy with the results, but it also looks like it needs scaling up."

Regards,
Tony Barry

[rj40]

Thanks MSimon and tonybarry.

So what it sounds like you're saying is that a "straightforward" neutron detection may not be necessary to prove this, and that other measures may do just as well. However, the "other methods" may require more explanation. Or, "The answers are going to be kind of nuanced." Is that about right?

[MSimon]

Thanks MSimon and tonybarry.

So what it sounds like you're saying is that a "straightforward" neutron detection may not be necessary to prove this, and that other measures may do just as well. However, the "other methods" may require more explanation. Or, "The answers are going to be kind of nuanced." Is that about right?

Pure guess work on my part, but yes.

[tonybarry]

From Dr. Khachan's explanation, the microwave interferometer shines a beam of microwaves onto a splitter, with one half of the microwave beam going through the region of interest in the polywell, and the other half of the beam taking a route which doesn't go through the polywell. The beams are recombined and impinge on a detector of microwaves, which form a kind of moire pattern or beat pattern depending on the detector. If there is an electron cloud in existence as it is supposed within the polywell, the moire pattern is shifted slightly in a well defined way which tells the seasoned user what the cloud density is within the polywell. This demonstrates confinement, or lack of it.

The aspects to note are the shift is slight, but measurable. The polywell need not be "operating" i.e. fusing species for this to occur. All that is needed is the electron cloud forming into a polywell electron dispersion. The effect occurs because the (tuned) microwaves interact with the free electrons and cause them to lose energy (i.e. are shifted downwards in frequency slightly).

I do not know if the resolution of a microwave interferometer is fine enough to show density changes across the region of interest.

Regards,
Tony Barry

[Tom Ligon]

Interesting possibility. They had a 90+ GHZ 4-beam microwave density-measurement system on HEPS.

[TallDave]

I think "nuanced" probably just means complicated, as in there are a lot of nuances to consider. He talks about complexity immediately before.

Because of the complexity, it will take some interpretation to determine exactly how the experiment is turning out. "The answers are going to be kind of nuanced," Nebel said.

I took that just to mean this isn't like turning a light switch and seeing whether the light goes on. There's a lot of complexity here, even just in how the results are measured as noted by tonybarry above with the inferometer.

As Nebel has pointed out, the wiffleball confinement is the crucial issue. If that works, even ion convergence isn't that important. If it doesn't, there's nothing here but an expensive science project.

[TallDave]

I'm not sure, but I'd have thought re-creating the neutron counts from WB-6 wouldn't have been nuanced, they'd be compelling.

Alas, probably not. It would remove a lot of the "only 3 neutrons" naysaying you hear from people who have only glanced at the topic, but many better-informed critics (such as Art Carlson in the MSNBC comments) often dismiss the WB-6 neutron counts as unimportant, even stipulating they are accurate, because their main argument is with things like brem or sputtering that would only become an issue when Q is around 1 or greater.

[Keegan]

He may not be looking for neutrons. The focus may be on confinement.

As Nebel has pointed out, the wiffleball confinement is the crucial issue.

Yes, i concurr. Its all down to confinement. When Dr Nebel speaks of "Nuanced results" it would seem to me a great deal of work has been been done in studying electron confinement, Beta conditions, stability of the virtual cathode / anode. These are all fundamental areas that could "make or break" the polywell. Im glad im hearing restrained optimism.

Neutrons have not been mentioned as they are probably leaving fusion till the end of the program. You risk irradiating/harming WB7 where the polywell is a unique design where you can explore the machines ultimate capabilities without actually slamming atoms together.


That is certainly interesting news about microwave inferometers Tony.

Interesting possibility. They had a 90+ GHZ 4-beam microwave density-measurement system on HEPS.

So Tom do you think we will see one on WB7. Did you know if they managed to get acceptable readings with the HEPS work ?

[Tom Ligon]

On their budget, it would be tight to put in a microwave system as fancy as HEPS had. That was up in the ten million range back in the late 80's. Dr. Bussard had me looking up equipment to try to do something similar, and I could not find a supplier that went above 50 GHz. (That was back before everyone had their catalogs on-line for search engines to find.)

The cross-section of the waveguides are like popsicle sticks ... tiny.

This was out of my league ... black art to me. MSimon might know better.

In HEPS they proved they had deep potential wells and the electrons basically behaved, but they could never get it to work with high plasma levels. It was pulsed, and large enough it may not have been on long enough to work. It was also a closed-box design, and must have had high electron losses.

WB6 had a lot of runs before they went to deuterium and fusion attempts, characterizing the electron behavior.

[Tom Ligon]

Just to make sure you are aware, the comments that follow Boyle's Nebel interview continue on a second page. There are three rounds of back-and-forth between Carlson and Nebel at this time, the latest made by Dr. Nebel about an hour ago as this is posted.

[MSimon]

On their budget, it would be tight to put in a microwave system as fancy as HEPS had. That was up in the ten million range back in the late 80's. Dr. Bussard had me looking up equipment to try to do something similar, and I could not find a supplier that went above 50 GHz. (That was back before everyone had their catalogs on-line for search engines to find.)

The cross-section of the waveguides are like popsicle sticks ... tiny.

This was out of my league ... black art to me. MSimon might know better.

My technology base extends out to about 100 MHz. You can still use real wires if you are careful. After that: black art. I did work with guys who adjusted their circuit elements with Xacto knives so I'm not unfamiliar with what goes on. Just unpracticed.

To make the argument with Carlson easier to follow:

http://cosmiclog.msnbc.msn.com/archive/ ... 7.aspx?p=1