Evanescent-Mode Microwave Plasma Jet for Low-Power Stable Discharge

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Solution Overview

Problem

Current plasma jets are inefficient, energy-hungry, bulky, and expensive, requiring high power consumption and posing safety concerns, while microwave plasma jets with resonant structures are costly and inefficient due to high voltages and electromagnetic compatibility issues.

Innovation Solution

A plasma jet assembly utilizing a cavity resonator with a metallic post and a radio frequency port to couple electromagnetic energy, creating a gas channel that directs gas flow to concentrate the electric field, facilitating plasma formation and sustainment with low power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-voltage pulses or high-power RF sources are used to ignite and sustain plasma, then plasma stability is achieved, but power consumption increases and device size becomes bulky

Engineering Contradiction:

Improveplasma stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies microwave resonance (electromagnetic vibration) to generate plasma. The cavity resonator sustains electromagnetic oscillations at microwave frequencies, creating intense electric fields that ionize gas molecules and sustain plasma without requiring high-voltage pulses or high-power RF sources, thereby reducing power consumption while maintaining plasma stability

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The patent changes the operating parameters by using microwave frequency electromagnetic waves instead of conventional RF or DC methods. This parameter change enables plasma generation at lower power levels while achieving stable plasma discharge through resonant field enhancement in the cavity structure

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If microwave resonant structures are used to achieve high-efficiency plasma, then power consumption decreases, but device cost increases and electromagnetic compatibility issues arise

Engineering Contradiction:

Improvepower consumptionVSAvoiddevice cost

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The cavity resonator structure serves multiple functions: it confines and enhances microwave fields for efficient plasma generation, acts as a compact housing for the plasma discharge region, and provides a controlled environment for gas flow. This multi-functionality reduces the need for additional components, lowering device cost and complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements a nested structure where the plasma discharge region is contained within the cavity resonator, and the gas flow channel is integrated within the cavity structure. This nesting approach minimizes the overall device footprint and reduces the number of separate components, thereby reducing manufacturing cost and complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If conventional plasma jets are used, then plasma generation is achieved, but device size becomes bulky and safety concerns increase

Engineering Contradiction:

Improveplasma generationVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

By using microwave resonance to generate intense electric fields in a compact cavity, the patent achieves plasma generation in a much smaller device footprint compared to conventional plasma jets that require large RF generators and transmission lines, thereby reducing device size while maintaining reliable plasma generation

Inventive Principle:

Principle #18Mechanical vibration

Solution Approach 2:

The cavity resonator acts as an intermediary that converts low-power microwave input into high-intensity localized electric fields necessary for plasma generation. This intermediary structure enables compact device design by decoupling the low-power input requirement from the high-intensity field requirement at the plasma discharge point

Inventive Principle:

Principle #24Intermediary (Mediator)

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 plasma jet assembly achieves higher efficiency, lower energy consumption, a compact form factor, and improved safety compared to conventional plasma jets, enabling applications in plasma medicine, decontamination, and reconfigurable RF electronics.

Implementation Method 1

employ microwave resonant structures to achieve high-efficiency plasma with low power consumption. The main principle is to utilize resonators that can concentrate the electromagnetic fields over a small gap

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

resonators that can concentrate the electromagnetic fields over a small gap. In this case, even with considerably low levels of input power, the magnitude of EM fields over those critical gaps can reach the breakdown threshold

Methodology Applied

Scientific EffectElectromagnetic field concentration: Focusing

Implementation Method 3

a gas channel within the metallic material and configured to direct a flow of a gas (i) to a space adjacent the metallic material where an electric field concentrates

Methodology Applied

Scientific EffectGas flow: Convection