Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
Author: Subject: Deuterium Deuterium fusion neutron production?
Precious
Harmless
*




Posts: 2
Registered: 30-11-2014
Member Is Offline

Mood: No Mood

thumbdown.gif posted on 30-11-2014 at 12:12
Deuterium Deuterium fusion neutron production?


Does this fusion make neutrons?
Everybody says it does, yet I think it doesn't.

Deuterium has 1 proton and 1 neutron. When it fuses it will produce 4-He with 2 neutrons, correct?

Where is neutron there ??? Nothing is ejected!
The newly formed isotope 4-He is perfectly stable.
View user's profile View All Posts By User
unionised
International Hazard
*****




Posts: 4022
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 30-11-2014 at 12:34


No.
http://en.wikipedia.org/wiki/Nuclear_fusion

It gives
3He and a neutron or
3H and a proton
each of those reactions happens about half the time.
View user's profile View All Posts By User
Precious
Harmless
*




Posts: 2
Registered: 30-11-2014
Member Is Offline

Mood: No Mood

[*] posted on 30-11-2014 at 17:32


Quote: Originally posted by unionised  
No.
http://en.wikipedia.org/wiki/Nuclear_fusion

It gives
3He and a neutron or
3H and a proton
each of those reactions happens about half the time.


Read that a month ago, but still can't understand.
I think that nuclear fusion only forms new element from two elements and not any other particles and radiations. Simple as that. Which element depends on the starting elements, and which isotope depends on the starting isotopes. All I do is calculate number of protons and neutrons to know which element is formed from fusion.

And only after that I look if that isotope of element decays via some radiation and particles (like neutrons).

Correct me if I'm wrong.

For example, I understand how fusion of Tritium and Deuterium forms neutron. Here's how:

2-H (1p+1n) + 3-H (1p+2n) => 5-He (2p+3n)

Now I look at Wikipedia to see if 5-He is stable, and I see that it isn't. 5-He releases neutron (immediately) and 4-He (stable isotope) is left behind.

So I understand how D-T fusion releases neutron, but don't understand nor believe how D-D fusion releases neutron!

Is there any evidence and explanation about why does D-D fusion releases neutron?
View user's profile View All Posts By User
UnintentionalChaos
International Hazard
*****




Posts: 1454
Registered: 9-12-2006
Location: Mars
Member Is Offline

Mood: Nucleophilic

[*] posted on 30-11-2014 at 17:55


Quote: Originally posted by Precious  

I think that nuclear fusion only forms new element from two elements and not any other particles and radiations. Simple as that.


Which is wrong. End of story.




Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
View user's profile View All Posts By User
Bert
Super Administrator
Thread Moved
30-11-2014 at 18:46
neptunium
International Hazard
*****




Posts: 922
Registered: 12-12-2011
Location: between Uranium and Plutonium
Member Is Offline

Mood: meta stable

[*] posted on 1-12-2014 at 12:42


fusion requires lots of energy to even begin some of that energy remains with the newly form isotope which release that excess by ejecting a particle or a gamma ray.
Nuclear physics isnt like chemistry in the sense that multiple reactions are possible but some more marginal than others.
He4 is a very stable isotope and in a plasma (which is the state of matter involve at these temperature) the nucleus release are still carying a great deal of energy after reaction, too much to condense in a stable isotope that would kill the reaction process instantly.
In a D-D reaction, the extra weackly bonded neutron (or proton) just takes some of that energy away most of the time. He4 can indeed form but in extremely rare instances.




Http://www.d-radlab.com/
View user's profile Visit user's homepage View All Posts By User
unionised
International Hazard
*****




Posts: 4022
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 1-12-2014 at 12:53


Quote: Originally posted by Precious  

Is there any evidence and explanation about why does D-D fusion releases neutron?


Well, there's plenty of evidence that it does- even amateurs* can get it to work
http://www.fusor.net/
So your assertion that it doesn't is plainly wrong.

*Just in case anyone is wondering, "Amateur" is not a bad thing, it just means they don't get paid to do this.
View user's profile View All Posts By User
careysub
International Hazard
*****




Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline

Mood: Lowest quantum state

[*] posted on 1-12-2014 at 15:45


Quote: Originally posted by neptunium  
fusion requires lots of energy to even begin some of that energy remains with the newly form isotope which release that excess by ejecting a particle or a gamma ray.
...
He4 can indeed form but in extremely rare instances.



If you look at a table of fusion reactions, none of them produce single products in the most common result.

It is the conservation of momentum that makes multiple product fusion reactions the rule, and single product reactions very rare.

The problem is that there must be exactly the same momentum in the reaction products as in the original reactants. Unlike energy (also conserved, but can be converted to different forms) the reaction can't just dump out excess energy as a photon or two. The only way to dispose of excess momentum is to emit another massive particle.

So when two deuterium nuclei collide, to form a single helium nucleus their momenta must exactly cancel - i.e. it must be a direct head-on collision. This hardly ever happens.
View user's profile View All Posts By User
careysub
International Hazard
*****




Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline

Mood: Lowest quantum state

[*] posted on 1-12-2014 at 15:51


Quote: Originally posted by Precious  
I think that nuclear fusion only forms new element from two elements and not any other particles and radiations. Simple as that.


It would be correct to say that nuclear fusion reactions never forms only one new element and not any other particles and radiations.

Conservation of momentum requires that there be at least two nucleon products in any fusion reaction, except for very rare exact head-on collisions (and in that case there will be a whopping big gamma ray to dump the energy).
View user's profile View All Posts By User
neptunium
International Hazard
*****




Posts: 922
Registered: 12-12-2011
Location: between Uranium and Plutonium
Member Is Offline

Mood: meta stable

[*] posted on 1-12-2014 at 18:26


Quote: Originally posted by careysub  
Quote: Originally posted by neptunium  
fusion requires lots of energy to even begin some of that energy remains with the newly form isotope which release that excess by ejecting a particle or a gamma ray.
...
He4 can indeed form but in extremely rare instances.



If you look at a table of fusion reactions, none of them produce single products in the most common result.

It is the conservation of momentum that makes multiple product fusion reactions the rule, and single product reactions very rare.

The problem is that there must be exactly the same momentum in the reaction products as in the original reactants. Unlike energy (also conserved, but can be converted to different forms) the reaction can't just dump out excess energy as a photon or two. The only way to dispose of excess momentum is to emit another massive particle.

So when two deuterium nuclei collide, to form a single helium nucleus their momenta must exactly cancel - i.e. it must be a direct head-on collision. This hardly ever happens.



which is exactly what i was trying to explain... but Creysub has a beter way of saying it ... spot on..




Http://www.d-radlab.com/
View user's profile Visit user's homepage View All Posts By User

  Go To Top