Vacuum Electron Device Service Life Prediction
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Solution Overview
Problem
Existing vacuum electron devices (VEDs) face challenges in predicting their end of service life due to non-linear depletion of electron emitting materials when operated at fixed filament voltages, leading to unreliable estimation and potential premature failure.
Innovation Solution
A method involving an adjustable voltage power supply that periodically adjusts the filament voltage while monitoring beam current, determining a knee-point where current decreases, and calculating remaining service life based on a predetermined filament voltage vs. service life relationship, allowing for display or indication of service life remaining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filament voltage is held constant, then the device operates stably, but the beam current exhibits roll-off leading to premature end of life
Solution Approach 1:
The patent applies dynamics by transitioning from a static filament voltage to a dynamic, adjustable filament voltage that changes over time. The system periodically adjusts the filament voltage while monitoring beam current, determining a knee-point where current begins to decrease, and calculating remaining service life based on the voltage-service life relationship. This dynamic adjustment extends the effective service life of the VED by adapting the operating conditions to the aging state of the electron emitting material.
2Productivity
If the filament voltage is increased, then the electron emission and beam current increase, but the electron emitting material is exhausted faster
Solution Approach 1:
The patent applies parameter changes by systematically varying the filament voltage parameter over time based on the aging state of the electron emitting material. The system monitors beam current at different filament voltages, determines the knee-point voltage where current begins to decrease, and uses this information to calculate remaining service life. This controlled parameter change allows optimization of both beam current output and service life duration.
3Duration of action of moving object
If the filament voltage is adjusted periodically, then the service life is extended, but the system complexity increases
Solution Approach 1:
The patent applies feedback by implementing a closed-loop system that periodically adjusts the filament voltage while monitoring the beam current. The system determines the knee-point voltage where current begins to decrease and uses this feedback information to calculate remaining service life based on a predetermined voltage-service life relationship. This feedback mechanism enables extended service life through adaptive control without requiring overly complex external systems.
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 extends the effective service life of VEDs by providing a reliable prediction of end of life, enabling users to manage inventory and maintain equipment effectively, with the adjustable voltage technique resulting in a more linear roll-off and extended operational lifespan.
Implementation Method 1
a cathode and a filament powered by an adjustable voltage power supply providing a voltage between a first low voltage and a second higher voltage to heat the cathode to an electron emitting temperature
Implementation Method 2
The electrons are emitted and formed into an electron beam which is generally modulated and amplified by the VED
Data Source
AI summary
The subject matter described herein generally relates to apparatus, systems, methods and associated computer instructions for predicting the end of service life of a space charge limited vacuum electron device. The device produces an electron beam current and has a cathode and a filament powered by an adjustable voltage power supply providing a voltage between a first low voltage and a second higher voltage to heat the cathode to an electron emitting temperature. The process includes periodically, while the device is in operation, adjusting the voltage provided by the power supply while monitoring the beam current, determining a knee-point in the voltage where the beam current begins to decrease as the voltage is decreased, and calculating, based on the determined knee-point and a predetermined voltage vs service life remaining relationship, the amount of service life left in the device.