Neutron Target Substrate Surface Modification for Blistering
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Solution Overview
Problem
Existing neutron generating targets for boron neutron capture therapy face challenges such as hydrogen impregnation leading to blistering and reduced lifetime, which complicates their use in hospital environments and requires costly maintenance, and existing methods for producing high neutron flux are often limited to nuclear research reactors.
Innovation Solution
A neutron generating target with a modified substrate surface featuring periodic or non-periodic surface features created through material removal or addition processes, combined with a neutron source layer like lithium or beryllium, which is bonded to the substrate using thermal methods to reduce hydrogen concentration and prevent blistering, and a modularized rotating target architecture for efficient neutron production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat substrate surface is used for neutron source layer deposition, then the manufacturing process is simple, but hydrogen impregnation causes blistering and reduces target lifetime
Solution Approach 1:
The substrate surface is modified to have non-uniform local structures (dimples, grooves, or protrusions) rather than a flat surface. These local variations in surface topology create different proton stopping depths across the surface, preventing uniform hydrogen accumulation and the resulting blistering that limits target lifetime.
Solution Approach 2:
The substrate surface is pre-modified with dimensional features before depositing the neutron source layer. This preliminary surface preparation ensures that when protons strike the target, they encounter varying path lengths through the neutron source layer, distributing hydrogen accumulation and preventing blistering before it can occur during operation.
2Productivity
If nuclear research reactors are used for neutron production, then high neutron flux is achieved, but safety and nuclear materials handling become challenging
Solution Approach 1:
Nuclear research reactors (which rely on nuclear chain reactions) are replaced with accelerator-based neutron sources that use mechanical/electrical acceleration of ions. This substitution eliminates the need for nuclear fuel handling and reactor safety systems while maintaining high neutron flux production capability through the modified target design.
Solution Approach 2:
The neutron production mechanism is changed from nuclear fission in reactors to ion bombardment in accelerators. By changing the fundamental parameter of how neutrons are generated (from nuclear chain reaction to nuclear reaction induced by particle acceleration), the system achieves high neutron flux without the associated safety and materials handling challenges of nuclear reactors.
3Productivity
If the neutron source layer is made thick to increase neutron yield, then higher neutron flux is produced, but hydrogen accumulation increases causing more severe blistering
Solution Approach 1:
The neutron source layer is deposited on a surface with local dimensional variations, creating regions of different effective thickness. This local variation in thickness distributes the proton stopping depths, preventing uniform hydrogen accumulation even when the overall layer is thick enough to provide high neutron yield.
Solution Approach 2:
Instead of varying neutron source layer thickness in one dimension (which would create other problems), the patent introduces surface topology variations in the spatial dimension. The dimples, grooves, or protrusions create effective thickness variations across the surface area, allowing thick layers for high yield while distributing hydrogen accumulation through spatial variation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified target design significantly reduces blistering and extends the target's lifetime by distributing proton stopping depths, allowing for higher neutron flux production and easier implementation in hospital settings using accelerator-based neutron sources.
Implementation Method 1
heating the neutron source layer and the target substrate to an elevated temperature for a duration of time for form a bond between the neutron source layer and the target substrate
Implementation Method 2
distributing proton stopping depths, allowing for higher neutron flux production
Data Source
AI summary
Design and making methods of a neutrons generating target are described. In some embodiments, a surface of a target substrate can be modified to form one or more surface features. In some embodiments, a neutron source layer can be disposed on the surface of the target substrate. In some embodiments, the neutron source layer and the target substrate can be heated to an elevated temperature to form a bond between the two. In some embodiments, the surface modification of the target substrate can reduce blistering and material exfoliation in the target. The target can be used in boron neutron capture therapy.