1D time evolving electric field profile measurements with sub-ns resolution using the E-FISH method

Area of Science:

• Plasma Physics
• Laser Spectroscopy
• Nonlinear Optics

Background:

• Electric field measurements are crucial for understanding plasma behavior.
• Previous methods lacked sufficient spatial or temporal resolution for dynamic plasma studies.
• Electric field induced second harmonic generation (E-FISH) is a known phenomenon but its application for detailed measurements was limited.

Purpose of the Study:

• To present and validate a novel approach for measuring time-evolving electric field profiles in atmospheric pressure plasma discharges.
• To leverage recent advancements in laser and detection technology for enhanced electric field metrology.
• To achieve high spatial and temporal resolution in electric field measurements within plasmas.

Main Methods:

• Utilized electric field induced second harmonic generation (E-FISH) for electric field profiling.
• Employed a femtosecond laser focused to a line using a cylindrical lens for 1D spatial resolution (∼50 μm).
• Used an intensified charge-coupled device (ICCD) for detection and achieved a time resolution of 500 ps.
• Verified spatial resolution using a spatially periodic, localized electric field.

Main Results:

• Successfully performed calibrated 1D electric field measurements in a cold atmospheric pressure plasma jet.
• Observed the electric field propagating as an ionization wave.
• Determined the propagation velocity of the ionization wave to be approximately 0.3 mm/ns.

Conclusions:

• The E-FISH technique, enhanced by modern technology, is effective for spatially resolved electric field measurements in atmospheric plasmas.
• The study demonstrates the capability to capture dynamic electric field behavior, such as propagating ionization waves.
• This method offers a valuable tool for detailed characterization and understanding of atmospheric pressure plasma discharges.