Slatted MILO Cathode Structure for Longer HPM Pulses

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Solution Overview

Problem

Magnetically Insulated Line Oscillators (MILOs) struggle to achieve long pulses due to neutral desorption from the cathodes, which leads to impedance collapse and termination of electromagnetic radiation production.

Innovation Solution

The implementation of a slatted cathode in the MILO, which reduces the surface area and thereby decreases the number of desorbed neutrals, allowing for extended pulse lengths and improved pulse repetition rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a solid cathode is used to provide sufficient electron current, then the current requirement is met, but neutral desorption increases leading to impedance collapse

Engineering Contradiction:

Improveelectron currentVSAvoidneutral desorption

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The solid cathode is segmented into multiple slats arranged in a cylindrical configuration. This segmentation reduces the total surface area of the cathode while maintaining the necessary electron current output, thereby decreasing neutral desorption and preventing impedance collapse in the AK gap.

Inventive Principle:

Principle #1Segmentation

2Duration of action of moving object

If the cathode surface area is reduced to decrease neutral desorption, then pulse length is extended, but electron current may become insufficient

Engineering Contradiction:

Improvepulse lengthVSAvoidelectron current

Core Design Contradiction:

Duration of action of moving objectVSQuantity of substance

Solution Approach 1:

The slat configuration optimizes the local electron emission properties by arranging multiple narrow slats in a cylindrical pattern. This local restructuring maintains high current density at each slat surface while the overall surface area is reduced, enabling extended pulse length without sacrificing total electron current.

Inventive Principle:

Principle #3Local quality

3Duration of action of moving object

If neutrals are removed from the AK gap to extend pulse duration, then long pulses are achieved, but vacuum system complexity increases

Engineering Contradiction:

Improvepulse durationVSAvoidvacuum system

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

Instead of attempting to remove neutrals from the AK gap after they are desorbed, the slatted cathode design prevents excessive neutral accumulation in the first place by reducing the cathode surface area. This preliminary anti-action approach avoids the need for complex vacuum intervention systems.

Inventive Principle:

Principle #9Preliminary anti-action

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 use of a slatted cathode enhances the MILO's ability to produce longer pulses and increase the pulse repetition rate by reducing neutral desorption, thus overcoming the impedance collapse issue.

Implementation Method 1

neutral desorption from the cathodes

Methodology Applied

Scientific EffectDesorption: Desorption

Implementation Method 2

These neutrals are ionized by the incident electron beam

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

The electrons from the cathode are in such a large number that they produce a magnetic field. This magnetic field serves to insulate the electron flow

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 4

electrons are emitted from the cathode due to applied voltage (E field)

Methodology Applied

Scientific EffectElectric field acceleration: Electric Field

Data Source

PatentUS20250141404A1Slatted Cathode for Frequency Agility of MILO HPM Source

Publication Date: 2025.05.01 THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

A magnetically insulated line oscillator (MILO) that is a high power microwave (HPM) source. A cross field device with a plurality of azimuthally extending spaced apart slats.