Discharge-Based Photo Ionization Detector Plasma Alignment
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Solution Overview
Problem
Existing discharge-based photo ionization detectors for chromatography applications require a pure helium supply, which dilutes impurities and is not efficient in separating species effectively.
Innovation Solution
A discharge-based photo ionization detector with a plasma chamber and ionization zone, where a plasma-generating mechanism creates optical radiation used to ionize gas samples, and a plasma-localizing mechanism ensures the plasma is aligned with the outlet, allowing for efficient ionization without the need for a separate helium supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pure helium gas is supplied to the discharge zone, then the detector can generate UV radiation for ionization, but the helium dilutes the impurities from the chromatography column
Solution Approach 1:
The invention merges the discharge gas flow and sample gas flow into a single combined flow that passes through both the discharge zone and ionization zone. This eliminates the need for separate helium supply while ensuring that the same gas mixture containing impurities is exposed to both plasma generation and ionization detection, thereby preventing dilution of the analyte.
2Reliability
If a separate helium supply is used for the discharge zone, then stable plasma can be generated, but the device complexity increases
Solution Approach 1:
The invention makes the carrier gas from the chromatography column serve multiple functions: it acts as the discharge gas for plasma generation in the discharge zone and as the carrier gas for transporting impurities through the ionization zone. This multi-functional use of a single gas supply eliminates the need for a separate helium supply system while maintaining reliable plasma generation.
3Power
If the plasma volume is increased to improve ionization, then more radiation is generated, but the dilution effect on impurities increases
Solution Approach 1:
By merging the discharge and ionization zones into a continuous flow path where the same gas mixture passes through both regions, the invention ensures that the volume used for plasma generation is the same volume containing the impurities. This prevents the plasma volume from acting as a separate dilution chamber while still providing sufficient radiation for effective ionization detection.
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 configuration enhances the detection of gas species by generating a stable plasma that ionizes samples effectively, reducing the need for additional helium and improving the separation of impurities, leading to improved sensitivity and accuracy in chromatography analysis.
Implementation Method 1
a plasma-generating mechanism configured to apply a plasma-generating field across the plasma chamber so as to generate a plasma from said discharge gas
Implementation Method 2
generate a plasma from this discharge gas... the plasma emitting optical radiation
Implementation Method 3
an ionisation-measuring mechanism configured to measure an ionisation current resulting from a photo ionisation of the gas sample in the ionisation region by the optical radiation
Implementation Method 4
a plasma-localizing mechanism configured to apply a plasma-localizing field across the plasma chamber and positioned such that the plasma-localizing field localizes the plasma within the plasma chamber in alignment with the outlet
Data Source
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AI summary
A discharge-based photo ionisation detector (PID) for use with gas chromatography systems is provided. The PID includes a discharge zone in which a plasma can be generated, resulting in the emission of energetic photons. The PID further includes an ionisation zone in which the gas sample to be analysed is bombarded by the photons created in the discharge zone, photo ionising the impurities in the gas sample. The generated current is measured in order to measure the concentration of impurities in the gas sample. Plasma localizing of the plasma in the discharge zone and optical monitoring of the emission from the plasma in the discharge zone may be provided. Methods using such a PID with a split input from a chromatography column or with inputs from two different chromatography columns are provided.