Compact Magnetron Assembly Using Nested Permanent Magnets

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Solution Overview

Problem

Existing high-power magnetron systems are large and heavy due to the need for external magnetic field generators, which add significant size and weight, and require cooling systems, making them unsuitable for many applications.

Innovation Solution

A compact high-power magnetron assembly using a central cylindrical permanent magnet within the cathode and annularly surrounding anode magnets to generate a uniform magnetic field, eliminating the need for external power sources and cooling systems by placing magnets close to the interaction region, reducing the amount of magnetic material required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If external permanent magnets are used to generate magnetic field, then magnetic field can be generated, but the magnetron assembly becomes large and heavy

Engineering Contradiction:
Improvemagnetic field generation capabilityVSAvoidmagnetron assembly weight
Core Design Contradiction:
PowerVSWeight of stationary object

Solution Approach 1:

The patent embeds permanent magnets within the cathode structure itself, nesting the magnetic field generation component inside the existing magnetron assembly rather than placing it externally. This integration dramatically reduces the overall size and weight while maintaining the required magnetic field strength in the interaction region.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from external placement to internal embedding, changing the spatial dimension of magnet placement from outside the cathode to inside the cathode structure. This dimensional repositioning allows the magnetic field source to be closer to the interaction region, reducing the amount of magnetic material needed.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Power

If coils are used to generate magnetic field, then magnetic field can be generated, but the system requires external power source and cooling system adding size and weight

Engineering Contradiction:
Improvemagnetic field generation capabilityVSAvoidsystem complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The permanent magnets are self-generating magnetic fields without requiring external power sources. This eliminates the need for power supplies, control systems, and cooling mechanisms that would be required for electromagnetic coils, significantly reducing system complexity while maintaining magnetic field generation capability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the electromagnetic coil system (requiring electrical power and cooling) with a permanent magnet system that generates magnetic fields through intrinsic magnetic properties. This substitution eliminates the need for external power sources and cooling systems, simplifying the overall device architecture.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Power

If permanent magnets are placed external to cathode and anode, then magnetic field can be generated, but large amount of magnetic material is necessary

Engineering Contradiction:
Improvemagnetic field generation capabilityVSAvoidmagnetic material quantity
Core Design Contradiction:
PowerVSQuantity of substance

Solution Approach 1:

By nesting permanent magnets within the cathode structure, the patent positions the magnetic field source much closer to the interaction region between cathode and anode. This proximity dramatically increases magnetic field efficiency, requiring significantly less magnetic material to achieve the same field strength compared to external placement.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent concentrates magnetic field generation locally within the cathode structure at the interaction region, rather than using large external magnets. This localized approach optimizes magnetic field distribution where it is most needed, reducing the total quantity of magnetic material required while maintaining field strength in the critical interaction zone.

Inventive Principle:
Principle #3Local quality

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 provides a lightweight magnetron assembly capable of high repetition rate operation without cooling, reduces axial loss currents, and allows for longer interaction regions without longitudinal overmoding, achieving a substantially uniform magnetic flux density.

Implementation Method 1

a compact magnetic field generator configured to generate a specified magnetic field within the magnetron

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the anode magnet is configured to generate a majority of a magnetic flux within the interaction region

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 3

a cathode having a hollow cylinder form, and configured to emit electrons in response to receiving a supply of voltage from a power supply

Methodology Applied
Scientific EffectElectron emission: Electron Beam

Implementation Method 4

an anode concentrically surrounding the cathode and configured to attract the emitted electrons across an interaction region between the cathode and the anode

Methodology Applied
Scientific EffectElectrostatic attraction: Electric Field

Data Source

PatentEP3120373B1Compact magnet design for high-power magnetrons
Publication Date: 2022.12.21 RAYTHEON CO
  • EP3120373B1 patent drawingFigure 1
  • EP3120373B1 patent drawingFigure 2
  • EP3120373B1 patent drawingFigure 3~4A

AI summary

A high-power magnetron assembly (200) includes a high-power magnetron and a compact magnetic field generator (101, 201, 601). The high-power magnetron includes a cathode (240) configured to emit electrons in response to receiving a supply of voltage from a power supply. The high-power magnetron includes an anode (250) configured to concentrically surround the cathode and to attract the emitted electrons across an interaction region (540) between the cathode and the anode. The compact magnetic field generator includes a plurality of permanent magnets including: a cathode magnet (105, 405, 605) that has a longitudinal axis of symmetry (507) annularly and that is surrounded by the cathode and disposed within the magnetron; and an anode magnet (115a-f, 315, 430, 610) configured to annularly surround an outer perimeter of the magnetron. An arrangement of the plurality of permanent magnets concentrically about the longitudinal axis of symmetry forms a specified magnetic field within the interaction region that bounds the electrons emitted within the interaction region.