Donate Bitcoin

Donate Paypal


PeakOil is You

PeakOil is You

THE Nuclear Fusion Thread Pt. 2(merged)

Discussions of conventional and alternative energy production technologies.

Re: THE Nuclear Fusion Thread Pt. 2(merged)

Unread postby lpetrich » Sat 22 Sep 2018, 23:32:56

There is a certain problem with the first step in the proton-proton process. It involves the weak interaction.

Two protons by themselves cannot be bound. That's because they are the same flavor of elementary particle and thus cannot occupy the same quantum state. Likewise for neutrons. But a proton and a neutron are different flavors, and they can be bound, though not by much.

So to make deuterium from protium, two protons have to collide close enough to touch, and when they do so, one of them has to turn into a neutron by positive beta decay. Though one may object that the Sun is very bright by ordinary standards, it is also very large by ordinary standards, and the two effects cancel out. The Sun's energy generation per unit volume in its core is about 1/4 human resting metabolism (Nuclear fusion - Wikipedia).

So we are stuck with fusion reactions that conserve nucleon flavor. This means the likes of D + D, D + T, and D + He3.
User avatar
lpetrich
Lignite
Lignite
 
Posts: 245
Joined: Thu 22 Jun 2006, 02:00:00

Re: THE Nuclear Fusion Thread Pt. 2(merged)

Unread postby Tanada » Sun 23 Sep 2018, 04:38:34

lpetrich wrote:There is a certain problem with the first step in the proton-proton process. It involves the weak interaction.

Two protons by themselves cannot be bound. That's because they are the same flavor of elementary particle and thus cannot occupy the same quantum state. Likewise for neutrons. But a proton and a neutron are different flavors, and they can be bound, though not by much.

So to make deuterium from protium, two protons have to collide close enough to touch, and when they do so, one of them has to turn into a neutron by positive beta decay. Though one may object that the Sun is very bright by ordinary standards, it is also very large by ordinary standards, and the two effects cancel out. The Sun's energy generation per unit volume in its core is about 1/4 human resting metabolism (Nuclear fusion - Wikipedia).

So we are stuck with fusion reactions that conserve nucleon flavor. This means the likes of D + D, D + T, and D + He3.


Hence the fact I pointed out that P*P fusion resulting in D is a 1/10E27 event. If you read what I actually wrote instead of playing wikipedia you will see I am referring to P*D reactions not P*P.

P*D=He-3 as does nearly half of D*D=He-3 + P
The difference being
P*D=He-3 + 5.49 MeV while
D*D=He-3 + P + 3.25 MeV
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
User avatar
Tanada
Site Admin
Site Admin
 
Posts: 15266
Joined: Thu 28 Apr 2005, 02:00:00
Location: South West shore Lake Erie, OH, USA

Re: THE Nuclear Fusion Thread Pt. 2(merged)

Unread postby Tanada » Sun 23 Sep 2018, 04:46:03

diemos wrote:
Tanada wrote:First off the P*D reaction does not appear on the graph you posted despite the fact that it is prevalent in the entire spectrum of dwarf class stars from brown dwarves right up through A stellar class objects.


It does not appear on that plot because it is too small.


If that were true it should be exceedingly easy for you to find a reference showing the reaction cross section for Protium*Deuterium fusion being exceedingly small.
Any reference from any physics oriented publication will do, not a random blog please.

Physics reaction cross sections of even rare reactions like Carbon-12*Helium-4=Oxygen-16 get published and those only take place at very high densities and temperatures. So finding references to H-2*H-1=He-3 which takes place in high density moderate temperature bodies should be a piece of cake for an expert like yourself.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
User avatar
Tanada
Site Admin
Site Admin
 
Posts: 15266
Joined: Thu 28 Apr 2005, 02:00:00
Location: South West shore Lake Erie, OH, USA

Re: THE Nuclear Fusion Thread Pt. 2(merged)

Unread postby diemos » Sun 23 Sep 2018, 06:40:18

Tanada wrote:If that were true it should be exceedingly easy for you to find a reference showing the reaction cross section for Protium*Deuterium fusion being exceedingly small.
Any reference from any physics oriented publication will do, not a random blog please.


https://www.nndc.bnl.gov/sigma/getInter ... f=3&mt=102

Peaks at about 1e-5 barns at 6e3 keV temperature.

http://www.kayelaby.npl.co.uk/atomic_an ... _7_4a.html

Same graph as before but in units of barns.

The piece that you're missing is that gas composition matters.

In a .5/.5 DT gas the particle interactions will be:
25% DD
50% DT
25% TT
and DT has the largest cross section and so DT fusion will be dominant.

In a .5/.5 PD gas the particle interactions will be:
25% PP
50% PD
25% DD
but DD has a 1000 times larger cross section than PD so almost everything will go through DD

In the sun it's almost all hydrogen with a tiny amount of deuterium, a 1.0/x PD gas. You'll get:
100% PP
x% PD
x^2% DD

As long as x is less than one part in a thousand, PD will dominate even with the larger cross section for DD fusion.

But if you can get a .5/.5 PD gas to fuse on earth (which will all be DD fusion) then you might as well use a 100% DD gas as that will give you 4 times as much fusion. And you might as well use a 100% DT gas as that will give you 10 times as much fusion from the higher cross section for DT fusion as compared to DD.

And that's the reason no one is pursuing PD fusion on earth even if it's the dominant mode in stars.
User avatar
diemos
Tar Sands
Tar Sands
 
Posts: 803
Joined: Fri 23 Sep 2005, 02:00:00

Re: THE Nuclear Fusion Thread Pt. 2(merged)

Unread postby StarvingLion » Mon 07 Jan 2019, 21:34:14

The Nuclear Magnetic Confinement Fusion Scam never dies. The Retards just can't accept that The Sun is an extremely low density energy device. From a human engineering perspective, its a hunk of junk.

https://futurism.com/fusion-power-practical

Expert: “I’m 100 Percent Confident” Fusion Power Will Be Practical
Companies chasing after the elusive technology hope to build reactors by 2030.
Dan RobitzskiJanuary 4th 2019
It’s Happening


Beyond ITER – next steps in fusion power
By Stuart Nathan 3rd January 2019 1:49 pm

https://www.theengineer.co.uk/beyond-it ... ion-power/

As assembly of ITER begins, scientists and engineers are already looking ahead to the technologies that will take fusion power a step closer to the grid. Stuart Nathan reports
Albanian Pyramid Schemers: "And the Federal Reserve laughed at us. Now look at their catastrophe"
StarvingLion
Heavy Crude
Heavy Crude
 
Posts: 1266
Joined: Sat 03 Aug 2013, 17:59:17

Previous

Return to Energy Technology

Who is online

Users browsing this forum: No registered users and 2 guests