He-3(n,p)H-3 Reaction: Fusion Rate Measurement by Neutron Count

  • Context: Graduate 
  • Thread starter Thread starter TESL@
  • Start date Start date
  • Tags Tags
    Reaction
Click For Summary

Discussion Overview

The discussion focuses on the He-3(n,p)H-3 reaction and its implications for measuring fusion rates through neutron counting, particularly in the context of D-D fusion reactions. Participants explore whether the absorption of neutrons by He-3 should be considered in fusion rate calculations and under what conditions it might be negligible.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the impact of the He-3(n,p)H-3 reaction on neutron count measurements for fusion rates, seeking clarity on when to consider He-3's neutron absorption.
  • Another participant suggests that the relevance of the cross-section indicates that He-3 absorption must be accounted for in calculations.
  • A later reply notes that the He-3(n,p)H-3 reaction has a very low microscopic cross-section, less than 1 barn above 1 MeV, and is primarily a thermal neutron absorber, implying a low probability of occurrence and suggesting that neutrons are more likely to escape the plasma.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of accounting for He-3 absorption in fusion rate calculations. While some acknowledge the low cross-section and probability of the reaction, others emphasize the importance of considering it based on cross-section relevance.

Contextual Notes

The discussion highlights the dependence on specific conditions such as neutron energy and density, which may influence the relevance of the He-3(n,p)H-3 reaction in fusion rate measurements.

TESL@
Messages
122
Reaction score
8
Since D-D fusion releases H-3 + p and He-3 + n, how does the reaction He-3(n,p)H-3 occurring affect measurement of fusion rate by neutron count?

In other words, do I have to take He-3 absorbing neutrons into account while calculating the fusion rate or in what conditions can I neglect it?

Thank you.
 
Physics news on Phys.org
If the cross-section is relevant, then sure you have to take it into account.
 
TESL@ said:
Since D-D fusion releases H-3 + p and He-3 + n, how does the reaction He-3(n,p)H-3 occurring affect measurement of fusion rate by neutron count?

In other words, do I have to take He-3 absorbing neutrons into account while calculating the fusion rate or in what conditions can I neglect it?

Thank you.
The He-3(n,p)H-3 has a very low microscopic cross-section, < 1 b, above 1 MeV. It is primarily a thermal neutron absorber.
http://www.nndc.bnl.gov/sigma/index.jsp?as=3&lib=endfb7.1&nsub=10

Combined the very low density, it is low probability of occurring, and the neutron is more likely to escape the plasma.
 
Thank you Astronuc.
 

Similar threads

  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 2 ·
Replies
2
Views
5K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 19 ·
Replies
19
Views
6K
  • · Replies 5 ·
Replies
5
Views
2K