Smoke Analysis Cell Sheath Flow for Plasma Stability
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Solution Overview
Problem
The clogging of analysis windows and portholes in LIBS cells due to the gaseous behavior of nanoparticles leads to reduced laser beam effectiveness, weaker plasma signals, and instability in signal acquisition, along with the formation of secondary plasmas outside the observation zone.
Innovation Solution
A characterization cell with a blower for sweeping inert gas near the analysis window and a sheath injector for coaxial sheathed injection of smoke, combined with a venturi design for overpressure and adjustable gas flows, to confine nanoparticles and maintain stable plasma observation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If nanoparticles are allowed to spread freely in the reaction chamber like a gas, then they can be easily introduced and analyzed, but the analysis window gets clogged and the plasma signal weakens
Solution Approach 1:
The patent applies local quality by creating a sheath flow of inert gas specifically around the smoke jet near the analysis window, while allowing free smoke distribution in the bulk reaction chamber. This localized control prevents clogging at the critical analysis window region without restricting overall smoke introduction and distribution in the chamber.
Solution Approach 2:
The patent introduces an intermediary substance (inert gas sheath flow) between the smoke and the analysis window. This sheath flow acts as a protective barrier that prevents nanoparticles from depositing on the analysis window while allowing the laser beam to pass through and analyze the smoke without interference from clogged surfaces.
2Power
If the laser beam energy is increased to compensate for window clogging, then plasma formation can be maintained, but secondary plasmas form outside the observation zone
Solution Approach 1:
The sheath flow creates a localized region of controlled gas composition and flow characteristics precisely at the analysis window area. This local modification ensures that the laser energy is confined to the desired observation zone, preventing secondary plasma formation in surrounding areas while maintaining effective plasma generation where needed.
3Reliability
If the analysis window is kept clean by reducing smoke flow, then signal stability improves, but the quantity of smoke available for analysis decreases
Solution Approach 1:
The inert gas sheath flow serves as an intermediary that decouples the relationship between smoke quantity and window cleanliness. It allows high smoke flow rates to maintain sufficient analyte quantity while the sheath flow simultaneously prevents clogging, thus maintaining both signal stability and adequate smoke quantity for analysis.
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 stabilizes the plasma signal, reduces clogging, and confines nanoparticles within the observation zone, enhancing the efficiency and stability of the plasma analysis process.
Implementation Method 1
a blower (16); characterized in that the blower is configured to ensure sweeping of inert gas in the vicinity of the analysis window
Implementation Method 2
a sheath injector configured for sheathed injection of the smoke inside the reaction chamber, the sheath being provided by a jet of inert gas around the smoke
Implementation Method 3
When the laser beam F-laser is focused in the mixture to be analyzed, there is vaporization of the nanoparticles causing the ejection of atoms and forming a plasma
Implementation Method 4
When the plasma expands, the atoms de-excite causing the emission of light
Implementation Method 5
the cell further comprises an arm extending from the reaction chamber and one free end of which is closed by the analysis window, this arm being formed of two parts of different straight sections, the part of larger section being arranged on the side of the analysis window and the part of smaller section being placed on the side of the reaction chamber to form a venturi and ensure overpressure on the side of the window
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a smoke analysis characterization cell employing optical spectroscopy, which comprises: a reaction chamber; an inlet orifice (111) for injecting smoke into the reaction chamber; an outlet orifice (121) for discharging the smoke from the reaction chamber; and an analysis window (131) for the entry of a laser beam (Flaser) intended to form the plasma inside the reaction chamber, which cell is characterized in that the system further includes a blower for blowing an inert gas close to the analysis window (131); and a shielding gas injector for the shielded injection of the smoke into the reaction chamber, the shielding being provided by a jet of inert gas around the smoke.