Journal of Fusion Energy

, Volume 35, Issue 2, pp 142–147 | Cite as

A Neutron Diode for Subcritical Multistage Multipliers with Special Reference in Tritium Breeding

  • Francisco J. Arias
  • Geoffrey T. Parks
Review Article


In this paper the interaction between a magnetic field and the neutron spin magnetic moment is explored for use in the design of a neutron diode or valve that allows a neutron flux to pass in one direction, while preventing a neutron flux in the opposite direction. A neutron diode that ensures the unidirectional movement of neutrons could be used in the design of a subcritical multistage neutron multiplier, a device that has thus far not been realised. With a subcritical multistage neutron multiplier, an initial source of neutrons could be multiplied substantially in a very small area. Such a device could have potential applications in tritium breeding in a fusion reactor, in medicine, in space exploration, etc. Utilizing a simplified geometrical model, a first preliminary study is performed to assess the feasibility of this concept.


Subcritical multistage multiplier Neutronic flux Tritium breeding 

List of symbols





\({\mathbf {B}} \)

Magnetic field

\(E_n \)

Energy of the neutron



\(^3H \)

Rate of tritium breeding



\(m_n \)

Mass of the neutron

\(M_n \)

n-Stage subcritical multiplication factor

\(M_1 \)

Single-stage subcritical multiplication factor


Number of stages






x-axis coordinate

\(X_1 \)

Displacement in x-direction


z-axis coordinate

\(Z_1 \)

Displacement in z-direction

Greek symbols

\(\epsilon \)

Loss factor

\(\theta \)

Angular separation

\(\kappa \)

Neutron multiplication factor

\(\mu _{S_{z}} \)

Spin-magnetic momentum of the neutron

\(\Phi \)

Neutronic flux from fusion core

Subscripts symbols






n stages


One stage


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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Department of EngineeringUniversity of CambridgeCambridgeUK
  2. 2.Department of Applied PhysicsUniversity of CadizPuerto RealSpain

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