Ion Source With Negatively Biased Extractor for Well Logging
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Solution Overview
Problem
Current ion sources for radiation generators in well logging instruments are limited in their ability to generate a large number of ions for a given power consumption, which restricts the amount of information that can be collected about oil formations and is inefficient in terms of power usage.
Innovation Solution
An ion source configuration that includes an active cathode emitting electrons to interact with an ionizable gas, with an extractor and suppressor system to accelerate ions into a target, utilizing pulsed potentials to enhance ion extraction and focusing, thereby increasing neutron generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ion sources are used in radiation generators, then the device can operate with standard power consumption, but the number of ions generated and neutrons produced is limited
Solution Approach 1:
The patent applies dynamic voltage modulation to the extractor electrode, switching between different voltage levels (e.g., -200V to -1000V) based on the operational phase. During ionization phases, lower extraction voltage preserves ions, while during extraction phases, higher voltage rapidly removes ions. This dynamic control optimizes both ion generation efficiency and extraction speed, resolving the contradiction between productivity and energy consumption.
Solution Approach 2:
The ion source operates in periodic cycles alternating between ionization mode and extraction mode. During ionization, the extractor is held at a mild negative potential to allow efficient ion generation. During extraction, the potential is increased to rapidly extract accumulated ions. This periodic action maximizes ion production per unit energy by preventing ion loss during non-extraction periods while maintaining high extraction efficiency when needed.
2Productivity
If higher extraction voltage is applied continuously to increase ion extraction efficiency, then more ions are accelerated into the target, but electron loss increases and ionization efficiency decreases
Solution Approach 1:
The extractor voltage is dynamically adjusted based on operational requirements rather than maintained at a constant high level. During ionization phases, voltage is reduced to minimize electron loss and maximize ionization efficiency. During extraction phases, voltage is increased to maximize ion removal. This dynamic adjustment resolves the contradiction by applying high extraction voltage only when necessary, not continuously.
Solution Approach 2:
The system performs preliminary ion accumulation during ionization phases at lower extraction voltages, allowing ions to build up in the extraction region. When extraction is initiated, the pre-accumulated ions are rapidly removed with high voltage. This preliminary action ensures that high extraction voltage is applied only briefly when needed, minimizing total electron loss while maintaining high extraction 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 configuration significantly increases the number of ions accelerated and neutrons generated, improving the efficiency and effectiveness of well logging applications by up to 40% while optimizing power usage.
Implementation Method 1
an active cathode configured to emit electrons on a trajectory away from the active cathode
Implementation Method 2
at least one extractor downstream of the active cathode having a potential such that the ions are attracted toward the at least one extractor
Implementation Method 3
the ions are accelerated through the suppressor and into the target to thereby generate neutrons
Data Source
AI summary
An ion source for use in a radiation generator includes an active cathode configured to emit electrons on a trajectory away from the active cathode, at least some of the electrons as they travel interacting with an ionizable gas to produce ions. In addition, there is at least one extractor downstream of the active cathode having a potential such that the ions are attracted toward the at least one extractor.