Electrical Ionizer for Aerosol Charge Conditioning
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Solution Overview
Problem
Existing electrical ionizers fail to accurately condition aerosol particles for size distribution measurement by differential mobility spectrometry due to inability to generate a Boltzmann charge distribution, and the use of radioactive ionizers is becoming less attractive due to regulation and safety concerns.
Innovation Solution
An electrical ionizer using a chamber with a conductive enclosure and an electrode to create a corona discharge, generating both positive and negative ions by AC voltage, ensuring a nominal gas flow path through a region of lower electric field intensity to achieve a Boltzmann charge distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radioactive ionizers are used for aerosol charge conditioning, then accurate Boltzmann charge distribution is achieved, but safety concerns and regulatory restrictions increase
Solution Approach 1:
The patent replaces the radioactive ionizer (nuclear physics mechanism) with an electrical corona discharge ionizer (electrical mechanism). The corona discharge electrode generates positive and negative ions through electrical field ionization of gas molecules, substituting the radioactive decay mechanism while achieving the same functional outcome of aerosol charge conditioning without safety or regulatory concerns
Solution Approach 2:
The patent changes the fundamental operating parameter from radioactive decay (constant, uncontrollable) to controllable electrical discharge parameters (voltage, current, gas flow rate). By adjusting these electrical parameters, the system achieves the desired Boltzmann charge distribution while providing operational flexibility and eliminating radioactive material handling issues
2Measurement precision
If complex electrical ionizers are designed to generate Boltzmann charge distribution, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the ionization chamber into distinct functional regions: a corona discharge region with high electric field intensity for ion generation, and a measurement region with low electric field intensity for accurate aerosol charging. This segmentation allows each region to perform its specific function optimally while keeping the overall device design straightforward
Solution Approach 2:
The patent introduces a conductive enclosure as an intermediary element that shapes and controls the electric field distribution within the chamber. This enclosure acts as a field-shaping mediator, creating the necessary high and low field intensity regions without requiring complex electrode configurations or additional active components
3Ease of operation
If electrical ionizers are used instead of radioactive ionizers, then safety and simplicity improve, but ability to generate Boltzmann charge distribution deteriorates
Solution Approach 1:
The patent employs AC voltage applied to the corona discharge electrode, creating periodic reversal of electric field polarity. This periodic action ensures that both positive and negative ions are generated continuously, allowing the aerosol particles to achieve the characteristic Boltzmann charge distribution where particles can acquire either positive or negative charges according to statistical equilibrium
Solution Approach 2:
The patent uses dynamic control of the corona discharge parameters (AC voltage amplitude, frequency, gas flow rate) to optimize ion generation and distribution. By dynamically adjusting these parameters, the system achieves the desired Boltzmann charge distribution while maintaining operational simplicity and safety, proving that electrical ionizers can match radioactive ionizer performance
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 enables accurate aerosol charge conditioning, achieving results comparable to radioactive ionizers while being simpler, more reliable, and safer, ensuring accurate aerosol size distribution measurements.
Implementation Method 1
the electrode being held at a different potential from the ground potential of the chamber wall. The electrode is connected to a source of voltage sufficient to cause a corona discharge to occur, forming an electric field and ions in the chamber
Implementation Method 2
causing a corona discharge to occur, forming an electric field and ions in the chamber
Data Source
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AI summary
An apparatus is disclosed for exposing particles in a gas in order to cause the charge on the particles to change, the apparatus comprising a chamber with an inlet for the gas to enter and an outlet for the gas to exit. The chamber is surrounded by an enclosure with a conductive wall, the wall being held at a ground potential. An electrode with an exposed tip is in contact with the gas in the chamber, the electrode being held at a different potential from the ground potential. The electrode is connected to a source of voltage sufficient to cause a corona discharge to occur forming ions in the chamber, and creating a region of space with a high electric field intensity and another region of space in which the electric field intensity is lower. The inlet and outlet define a gas flow path from the inlet to the outlet such that the gas flow path passes mainly through the region with the lower electric field intensity.