Laser-induced plasma imaging for low-pressure detection

Area of Science:

• Physics
• Materials Science
• Analytical Chemistry

Background:

• Residual pressure measurement is critical for sealed systems like high-voltage vacuum interrupters.
• Current methods may require direct contact or invasive procedures.
• A non-contact, gauge-free method is desirable for efficient and safe pressure monitoring.

Purpose of the Study:

• To introduce and validate a novel technique for measuring residual pressure in sealed containers using laser-induced plasma imaging.
• To demonstrate the feasibility of this method across a wide pressure range (10⁻² Pa to 10⁵ Pa).
• To establish the accuracy and repeatability of the proposed pressure measurement approach.

Main Methods:

• Laser-induced plasma (LIP) was generated on a copper target within sealed containers at various pressures.
• Plasma plume images were captured at different delay times (200-800 ns).
• A subsection characteristic method analyzed plasma shape, intensity, and expansion dynamics to determine pressure.

Main Results:

• Plasma plume characteristics (shape, intensity, expansion) were found to be significantly dependent on ambient gas pressure.
• The subsection characteristic method successfully extracted pressure values from plasma images.
• The technique demonstrated good repeatability across all tested pressures and delay times.

Conclusions:

• Laser-induced plasma imaging is a viable and promising technique for gauge-free residual pressure detection.
• The developed method offers an accuracy within 15% of nominal values over a broad pressure range.
• This approach provides a non-invasive solution for pressure monitoring in transparent-walled sealed containers.