More Upgrades

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Richard Hull
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Re: More Upgrades

Post by Richard Hull » Sun Apr 28, 2019 4:12 am

I was indeed quoting and am familiar with the D-D curve. All easy, useful slope disappears at 100kev and it really is useless much beyond 200kev in amateur hands. Forget Xrays. The slope and return in fusion for all future 100kev advances are just not worth the extra 100kev effort. (shielding, state licensing, irradiating the cat or dog, other family members and the neighbors.

Finally, being a log-log plot one can't help but notice that going from 300kev to 3mev you get a 10% increase in cross section.... worthless.....
We can't help but notice a full order of magnitude increase from 40kev to 100kev, beyond which, the "forlorn hope" begins, slope-wise.

It is a matter of losing slope fast to the point and that pouring in more juice just ain't worth the hassle in amateur hands.

Reason and logic coupled with amateur hands in a family home limit us all in a fusion effort. Smart folks can observe the slope. Reason and logic, reason and logic.

Once you actually have 100kv applied and are still alive, 50kv or 100kv more heaped on, is a real stretch...How much of the tapering off slope is one willing to chase?

Beam on target in a well done system will always outperform a "simple amateur fusor" even at 10% duty cycle at most any voltage. When I say simple amateur fusor, this means no ion guns, no extra ionizing or suppression field control grids. This is the kind of fusor that is made here.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Bruce Meagher
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Re: More Upgrades

Post by Bruce Meagher » Tue Apr 30, 2019 2:29 pm

I misinterpreted your previous post. I thought you were implying the D-D fusion cross section decreased above 150 keV. My Bad. Even though there is only a small increase in cross section between say 100 and 200 keV the neutron production rate more than doubles over this interval. However, as your rightly point out, this is really irrelevant for the amateur effort.

Joe, I apologize for derailing your thread.

Bruce

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Richard Hull
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Re: More Upgrades

Post by Richard Hull » Tue Apr 30, 2019 5:17 pm

Bruce, no issue or scolding, just a restatement of limitations and realities in home grown fusion in a simple fusor. A clean and clear understanding is needed among newbies and the over unity hopefuls landing here.

While this thread is all about Joe working on his effort and to see it advance, we must also speak to those not currently doing beans on fusion to instruct in the practicalities involved, should they choose to start to actually do something. I often wonder how the very term "slope of cross sections" falls on ears that do not know what slope means. Such folks might do well to just move on as the far more involved work and understanding that lay ahead in a fusor effort is often, along with lack of funds, what kills an effort in progress.

Joe is certainly one of the most recent success stories and his efforts are expanding as he seems to be striving to see just how much he can wring out of his effort. Go Joe!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

ian_krase
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Re: More Upgrades

Post by ian_krase » Wed May 01, 2019 6:31 am

At what energy do things start heating up again?

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Richard Hull
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Re: More Upgrades

Post by Richard Hull » Wed May 01, 2019 4:58 pm

Beyond 2-3 mev, fusion backs off and the Oppenheimer-Phillips reaction takes over. This is called stripping where the deuteron is just dismantled into protons and neutrons in the D-D fusion scenario. It is why the cross section takes a nose dive beyond these energies. this has been in many posts here over the years.

https://en.wikipedia.org/wiki/Oppenheim ... ps_process

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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