An optical trapping system for particle probes in plasma diagnostics.

Area of Science:

• Physics
• Plasma Science
• Optical Physics

Background:

• Low-temperature plasma diagnostics are crucial for various applications.
• Accurate measurement of forces within plasma environments is challenging.

Purpose of the Study:

• To present a novel method for optically trapping microparticles.
• To utilize trapped microparticles as probes for low-temperature plasma diagnostics.
• To measure external forces acting on microparticles within plasma.

Main Methods:

• Employs a dual laser beam, counter-propagating optical trapping technique.
• Uses SiO2 microparticles as probes in low-temperature, low-pressure radiofrequency (rf) plasma.
• Measures forces by analyzing the displacement of trapped microparticles.

Main Results:

• Successfully optically trapped SiO2 microparticles at large distances in rf plasma.
• Verified the technique by measuring neutral gas damping.
• Demonstrated measurement of particle charge changes via UV radiation.
• Quantified forces acting on particles in plasma sheath and bulk regions.

Conclusions:

• Optical trapping of microparticles is a viable technique for low-temperature plasma diagnostics.
• The method allows for in-situ force measurements during plasma operation.
• This approach offers new possibilities for understanding plasma behavior.