Relativistic Magnetron Virtual Cathode Design
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Solution Overview
Problem
The lifetime of high power relativistic magnetrons is limited by intense electron bombardment of the cathode, leading to destruction and decreased efficiency due to cathode plasma expansion and gas expulsion, which also limits pulse repetition rates.
Innovation Solution
A magnetron design utilizing a virtual cathode formed by a dimensional discontinuity in the vacuum channel, where the electron beam current exceeds the space-charge-limiting current, eliminating the need for a physical cathode and reducing plasma expansion, with an external electron source and a magnetic mirror to suppress axial leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a physical cathode is used in a relativistic magnetron, then electron emission is achieved, but the cathode deteriorates over time due to intense electron bombardment and plasma expansion
Solution Approach 1:
The invention extracts the harmful physical cathode from the interaction space and replaces it with a virtual cathode formed by an electron beam. The electron beam is generated externally and injected into the magnetron, eliminating the physical cathode that suffers from electron bombardment damage and plasma expansion, thereby resolving the contradiction between achieving electron emission and preventing cathode deterioration
Solution Approach 2:
The invention introduces an intermediary electron beam as a mediator between the external electron source and the magnetron interaction space. This electron beam serves as the virtual cathode, providing the necessary electron source without requiring a physical cathode structure that would be damaged by intense electron bombardment and plasma effects
2Productivity
If a physical cathode is used in a relativistic magnetron, then microwave generation is enabled, but pulse repetition rate is limited due to cathode plasma expansion and gas expulsion
Solution Approach 1:
By removing the physical cathode and replacing it with an externally generated electron beam, the invention eliminates the plasma expansion and gas expulsion effects that limit pulse repetition rates. This allows for longer pulse durations and higher repetition rates without cathode degradation
Solution Approach 2:
The invention employs a dynamic electron beam that can be rapidly injected and controlled externally, allowing for flexible pulse timing and higher repetition rates. The electron beam parameters can be dynamically adjusted without being constrained by cathode recovery time or plasma effects
3Power
If resonator cavities are cut into the anode surface, then microwave generation is achieved, but the structure becomes complex
Solution Approach 1:
The invention segments the microwave generation function into separate resonator cavities that are coupled to the interaction space. This allows for modular design where the complexity of the resonant system is distributed across multiple cavities rather than requiring a single complex structure, enabling high power generation while managing structural complexity
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 design enhances the magnetron's efficiency and pulse duration, allowing for high power, long pulse, and high repetition rate microwave generation without cathode deterioration and ion back bombardment.
Implementation Method 1
a virtual cathode formed by a dimensional discontinuity in the vacuum channel, where the electron beam current exceeds the space-charge-limiting current
Implementation Method 2
where the electron beam current exceeds the space-charge-limiting current
Implementation Method 3
with an external electron source and a magnetic mirror to suppress axial leakage
Implementation Method 4
resonator cavities 15... Transverse electric-type (TE) eigenmodes of the resonant system are used as operating waves
Implementation Method 5
When the azimuthal phase velocity of one of eigenmodes of the resonant system is close to the azimuthal drift velocity of the electrons, energy of the electrons is transferred to this electromagnetic wave
Data Source
AI summary
The present invention provides a relativistic magnetron including an anode with an entrant channel, the channel having an input end, an output end and a dimensional discontinuity between the ends. The channel is connected to the magnetron and has an anode defining an interaction space located between the dimensional discontinuity and output end. Also provided is a cathode, located upstream, a spaced distance away from the interaction space towards the input end, the cathode is adapted to send an electron beam into the interaction space where the electron beam forms a virtual cathode in the interaction space.