Grounded Target Neutron Generator for Thermal Management
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Solution Overview
Problem
Sealed-tube neutron generators used in well logging tools face overheating issues due to poor thermal conduction of high voltage insulation, leading to reduced neutron output and potential failure.
Innovation Solution
A neutron generator design featuring a grounded target electrode and an RF-driven ion source with an external RF antenna, which reduces the need for high voltage insulation around the target, allowing for improved cooling and increased neutron output by operating the target at or near ground potential and using solid-form high voltage insulation to isolate high voltage components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage insulation is used to surround the target, then electrical insulation is provided, but thermal conduction is poor causing target overheating
Solution Approach 1:
The system is divided into high voltage and ground potential sections. The target electrode is separated from high voltage components by physical segmentation, allowing the target to be grounded while high voltage is applied to the ion source. This resolves the contradiction by enabling both electrical insulation (through spatial segmentation) and thermal conduction (through ground connection).
Solution Approach 2:
The patent introduces an intermediary approach by using the vacuum envelope and external RF antenna as mediators. The RF antenna couples energy to the plasma without direct electrical connection to the target, allowing electrical insulation while maintaining thermal pathways to the grounded target.
2Productivity
If conventional ion sources are used, then plasma is generated, but neutron output per unit beam current is limited
Solution Approach 1:
The patent changes the operating parameters by grounding the target electrode and applying RF power to the ion source instead of using conventional high voltage acceleration. This parameter change enables more efficient ion production and higher neutron yield per unit beam current while improving heat removal from the target.
Solution Approach 2:
The use of RF (radio frequency) periodic action to generate plasma in the ion source improves ion production efficiency compared to continuous DC discharge. The periodic RF fields more efficiently accelerate electrons for ionization, resulting in higher neutron output per unit beam current.
Data Source
AI summary
A neutron generator includes a sealed envelope providing a low pressure environment for a gas of hydrogen isotope(s). One end of the envelope defines an ion source chamber. A target electrode is disposed at the other end of the envelope. An extraction electrode is spaced apart from the target electrode by an accelerating gap. The extraction electrode bounds the ion source chamber. An RF antenna is disposed external to the sealed envelope in the vicinity of the ion source chamber. The RF antenna is used to transmit time-varying electromagnetic fields within the ion source chamber for producing plasma therein. The extraction electrode operates at a positive high voltage potential and the target electrode operates at or near ground potential in order to provide an electric field gradient that accelerates ions of the plasma towards the target electrode to induce collisions of ions with target material, thereby causing fusion reactions that generate and emit neutrons from the target material. High voltage insulation is disposed between the RF antenna and both the ion source chamber and the extraction electrode for electrically insulating the RF antenna operating at or near ground potential from the high voltages of the ion source chamber and the extraction electrode.