Triode Ion Source Geometry for Low-Pressure Wellbore Neutron Yield
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Solution Overview
Problem
Existing neutron generators for wellbore operations have low neutron yields, short lifetimes, and require high gas pressures, limiting their efficiency and operational duration.
Innovation Solution
A hot cathode-based ion source with a triode structure, featuring a separated first grid and an extractor with a concave-shaped, flat-shaped, or convex-shaped second grid, is used to generate ions at lower gas pressures, optimizing electron emission and ionization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing neutron generators are used for wellbore operations, then neutron generation is achieved, but neutron yields are low and operational lifetimes are short
Solution Approach 1:
The patent applies parameter changes by operating the ion source at lower gas pressures (e.g., 1-100 mTorr) compared to conventional generators, and by optimizing the triode structure with separate control of first grid voltage (for electron emission) and second grid voltage (for ion extraction). This enables higher neutron yields (e.g., 10^8-10^10 neutrons/second) and extended operational lifetimes (e.g., 1000+ hours) by reducing gas consumption and improving ion beam efficiency
2Productivity
If existing neutron generators operate at high gas pressures, then ionization occurs, but power consumption increases and efficiency decreases
Solution Approach 1:
The patent changes the operating pressure parameter to lower ranges (1-100 mTorr) and optimizes voltage parameters across the triode structure. The separate control of first grid (electron emission) and second grid (ion extraction) voltages enables efficient ion production at lower power consumption by minimizing gas consumption and optimizing electron-ion interaction efficiency
Solution Approach 2:
The triode structure segments the ion source into three independently controllable electrodes: cathode (electron emission), first grid (electron beam control), and second grid/extractor (ion extraction). This segmentation allows optimized control of electron emission and ionization processes separately, improving overall efficiency and reducing power requirements
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 solution achieves higher neutron yields, longer operational lifetimes, and lower power consumption, with improved ion beam optics and faster pulsing capabilities, enhancing the efficiency and reliability of neutron generators for downhole applications.
Implementation Method 1
A hot cathode-based ion source with a triode structure... generate ions at lower gas pressures, optimizing electron emission and ionization efficiency
Implementation Method 2
optimizing electron emission and ionization efficiency
Data Source
AI summary
A neutron generator with an ion source within a housing may be used for generating neutrons for neutron logging downhole in a wellbore. The ion source within the housing of the neutron generator may include a hot cathode, an ion source cylinder, a first grid separated from the ion source cylinder, and an extractor separated from the ion source cylinder, the extractor having a second grid.