Talk-Polywell.org

I've seen criticism of the WB-6 results that claim it only resulted in detection of "four neutrons" or other single digit numbers. I found this in the Polywell Wikipedia discussion from Tom:

The actual measurements on WB6 were neutrons detected, with about 1.3e4 neutrons produced per neutron detected, and it should work out to less than 1e9 per second by any means you look at it. I wish it had been more, and longer. Tomligon 19:10, 19 June 2007 (UTC)

OK, 1e+9 per sec over a quarter of a milli is...

1e+9 * 1e-3 = 1e+6 per milli, or .25e+6 for the whole run, or 25e+4, which works out to about 20 neutrons detected if we detect one for each 1.3e+4.

I think I recall there were 4 such runs (someone correct me if wrong here), so we'd be talking 80 neutrons detected, correct?

well if you look at the (seminal) 2006-9 IAC Paper

FIG 18, page 23 the WB-6 test run graph quotes

3.00 x 1.3e4 nts/ct @ 10 secs

If anyone has some better info on test runs id love to see it. Some one mentioned there was more conclusive paper on WB-6 inside the company. I would love to see that.

I Promise i wont give it to China. Promise

Yes, the graph is somewhat confusing, as it gives a time-scale in days. It seems to say they detected 3 neutrons three times.

Okay, tests were estimated at .4 milli. The Valencia paper says 3 neutrons detected on 3 occasions.

So... 1e9 per sec, 1e6 per milli, 4e5 for the test runs of . 4 milli. If detection is 1/1.3e4, then 4e5/1.3e4 works to 3e1, or 30.

Am I missing something here? Seems to be off by an order of magnitude. Is that the right detection #?

Each count is worth 1.3E4 neutrons due to geometry and counting efficiency.
Three counts were produced in .25 mS.

1.3E4 * 3 * 4E3 = 15.6 E7 or 1.56 E8

OK, I figured I had made a mistake somewhere, but looks like 1e9 was just a rough Bussard estimate. Fair enough, he's not exaggerating much.

Obviously, 1e8 is still very significant. Actually, I feel much more confident about this now that I have a better understanding of the test results. Four tests is pretty persuasive, and it seems very very unlikely they could have gotten that much noise four times in sucha small time window.

Can't wait for the new results! Hopefully we get to see something before the end of the year. (Hopefully that's allowed by the contract...)

The Tokamak I'm working on typically produces 4*10^13 neutron for a good one second long shot using pure Deuterium gas, it is a cylinder diameter 4 metres and height 4 metres.

jmc wrote:The Tokamak I'm working on typically produces 4*10^13 neutron for a good one second long shot using pure Deuterium gas, it is a cylinder diameter 4 metres and height 4 metres.

Give me the same dimensioned Polywell reactor (spherical of course) and I can get you on the order of 1E22 n/Sec or better. Continuously (at least in the 100s of seconds with LN2 cooled copper coils).

Does anyone know the exact dimensions of the outside of the WB6 vacuum vessel?

jmc wrote:Does anyone kmow the exact dimensions of the outside of the WB6 vacuum vessel?

Much bigger than necessary.

Here's another question with regard to the scaling, is the distance from the Magrid to the Earthed cage dependent only on the voltage and not on reactor dimensions? In the pictures, for example, the earthed cage surrounding the magrid appears to have twice the diameter of the magrid, if the volume enclosed by the magrid was say increased by a factor of 10 would the surrounding earthed cage appear to huge the magrid more tightly or is distance determined by magnetic topology or something that would mean the ratio would remain constant?

jmc wrote:Here's another question with regard to the scaling, is the distance from the Magrid to the Earthed cage dependent only on the voltage and not on reactor dimensions? In the pictures, for example, the earthed cage surrounding the magrid appears to have twice the diameter of the magrid, if the volume enclosed by the magrid was say increased by a factor of 10 would the surrounding earthed cage appear to huge the magrid more tightly or is distance determined by magnetic topology or something that would mean the ratio would remain constant?

The size of the vacuum chamber is dependent on the electron orbit radius. Thus the distance between the magrid and the vacuum chamber wall would decrease with increased magrid voltage and increase with electron energy. My uneducated guess would be that the distance from the magrid to the vacuum walls would not depend on the machine radius other than in changes to electron energy and magrid voltage that come with scaling up.

When you say electron orbit radius do you mean larmor radius or are you referring to the electrons going into the centre and out to maximum radius? If the vacuum wall was earthed then I would imagine the electrons would slow down on arrival to it independently of its distance from the magrid, the closer it is placed to the magrid, the stronger the electric field between it and the magrid and so the faster the electrons would slow down.

jmc wrote:When you say electron orbit radius do you mean larmor radius or are you referring to the electrons going into the centre and out to maximum radius? If the vacuum wall was earthed then I would imagine the electrons would slow down on arrival to it independently of its distance from the magrid, the closer it is placed to the magrid, the stronger the electric field between it and the magrid and so the faster the electrons would slow down.

By electron orbit I was referring to the electron's path outside the magrid and back to the centre. If the recirculating electrons get too close to the grounded walls they will be lost. It costs no energy to build a bigger vacuum chamber, so that's quite preferable to holding a smaller chamber at a negative potential.