Field-Ionization Neutron Generator for Precise Pulse Control
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Solution Overview
Problem
Conventional pulsed neutron generators face challenges in precise control over neutron pulse timing, limited neutron output, high ionization voltages leading to reliability issues, and complexity due to indirect electron and ion creation processes.
Innovation Solution
The use of direct field ionization in neutron generators with a cylindrical field-ionization structure and grid configuration reduces ionization time to sub-microseconds, achieves high monatomic ion populations, and lowers ionization voltage, resulting in significantly higher neutron yields and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If indirect electron impact ionization is used to create ions, then ionization can be achieved, but the time delay between voltage pulse application and neutron burst becomes variable and difficult to control precisely
Solution Approach 1:
The patent removes the intermediate electron generation step from the ionization process. By using direct field ionization where the electric field directly ionizes gas molecules without requiring electron acceleration and collision, the complex two-step process (electron generation then ionization) is reduced to a single direct step, eliminating the variable time delay and improving timing control precision.
Solution Approach 2:
The patent eliminates electrons as an intermediary in the ionization process. Instead of using electrons as the mediating particle that transfers energy from the electric field to gas molecules, the invention applies the electric field directly to ionize the gas, removing the intermediary step and its associated timing variability.
2Reliability
If conventional Penning ion sources are used, then ionization can be achieved, but additional components such as magnets are required which increase device bulk and complexity
Solution Approach 1:
The patent removes the magnet component from the ion source design. By using direct field ionization, the invention eliminates the need for magnetic fields to lengthen electron paths, thereby removing the magnet and its associated complexity while maintaining ionization functionality through the direct electric field approach.
Solution Approach 2:
The patent replaces the mechanical/magnetic system (magnets and electron trajectory manipulation) with a direct electric field system. Instead of using magnetic fields to control electron motion and increase collision probability, the invention uses a strongly focused electric field to directly ionize gas molecules, substituting a simpler electromagnetic mechanism for a more complex electromechanical one.
3Productivity
If high ionization voltages are applied in conventional generators, then ionization can be achieved, but electrical stresses increase which decrease reliability and lifetime
Solution Approach 1:
The patent applies local quality by concentrating the electric field in a highly focused region near the cathode tip rather than distributing it broadly. This localized field concentration achieves efficient ionization in a small volume with lower overall voltage, reducing electrical stresses on the entire system while maintaining high neutron output through the intense local ionization efficiency.
Solution Approach 2:
The patent changes the voltage parameter distribution from high voltage applied broadly across the ion source to lower voltage applied in a highly focused local region. By modifying how the voltage parameter is distributed (concentrated near the cathode tip rather than distributed), the invention achieves efficient ionization with reduced overall electrical stress, improving reliability and lifetime.
4Productivity
If deuterium and tritium gas is ionized through electron collisions, then ions are created, but the majority of ions formed are di-atomic reducing neutron output efficiency
Solution Approach 1:
The patent changes the ionization mechanism parameter from electron impact ionization to direct field ionization. This parameter change fundamentally alters the ionization process, enabling preferential formation of monatomic ions through direct electric field action on individual gas molecules, thereby increasing the monatomic ion population and neutron output efficiency.
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
This approach enables precise control over neutron pulse characteristics, increased neutron yields, and extended operational lifetime with reduced electrical stress, facilitating more effective pulsed neutron logging operations.
Implementation Method 1
Neutral fusion gas can be ionized in the field-ionization structure by applying a suitable negative electrical potential (or voltage) to the field-ionization grid (relative to the array of nanotips)
Implementation Method 2
Ions generated by the field-ionization structure accumulate inside the ion-acceleration grid, from which they can be axially extracted and accelerated, inside the ion-acceleration portion of the neutron generator, towards a fusion target
Implementation Method 3
The high-energy neutrons can be generated in fusion reactions of the hydrogen isotopes deuterium and/or tritium
Data Source
AI summary
Described herein are neutron generators that employ direct field ionization of ionizable fusion gases, as well as well-logging tools and methods that utilize such neutron generators. In various embodiments, the neutron generator includes a cylindrical field-ionization structure distributed around the inner surface of a tubular housing, and a cylindrical ion-accelerating grid disposed about the longitudinal axis concentrically to the field-ionization structure. Ions generated by the field-ionization structure may accumulate inside the ion-accelerating grid, from which they can be axially extracted and accelerated towards a fusion target. Additional tools, systems, and methods are disclosed.