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

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## Abstract

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.

## Keywords

Subcritical multistage multiplier Neutronic flux Tritium breeding## List of symbols

*a*Acceleration

*A*Area

- \({\mathbf {B}} \)
Magnetic field

- \(E_n \)
Energy of the neutron

*F*Force

- \(^3H \)
Rate of tritium breeding

*L*Distance

- \(m_n \)
Mass of the neutron

- \(M_n \)
*n*-Stage subcritical multiplication factor- \(M_1 \)
Single-stage subcritical multiplication factor

*n*Number of stages

*t*Time

*v*Velocity

*x*x-axis coordinate

- \(X_1 \)
Displacement in x-direction

*z*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

*b*Blanket

*s*Subcritical

*n**n*stages- 1
One stage

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