果冻传媒

Pockels-effect

For this technique, light passes through an electro-optic material under an electric field and experiences a retardance proportional to the field.

A characterization and comparison of the performance of the most commonly used Pockels setup configurations was presented by Anne Limburg as part of her PhD research.

This technique is useful for creating 2D surface charge maps with high time resolution and in-situ, though the setup in Limburg鈥檚 research lacked sufficient signal-to-noise ratio for detailed surface potential distribution analysis.

Furthermore, a tool for quantitative and spatially controlled surface charge deposition on dielectrics was developed, based on an X-ray ionizer.

Kerr-effect

The optical retardance in a material is proportional to the square of the electric field, applicable to all materials.

This technique was used by Limburg to validate electric field models in synthetic ester (SE) and cellulose press paper insulation systems, revealing non-negligible fields in SE and better accuracy with the Planck-Nernst-Poisson model under non-Ohmic conditions compared to the quasi-Ohmic conduction model.

E-FISH

This technique uses a high-power laser to induce light at twice the frequency of the laser, with the power of this second harmonic indicating the electric field strength.

Limburg鈥檚 thesis highlights the impact of phase effects on the acquired electric field distribution and the invasiveness of the probing laser on a plasma, proposing solutions for cylindrically symmetric plasmas.

This results in the presentation of a high resolution electric field distribution measurement of a single channel streamer discharge obtained with E-FISH.

Overall, the PhD research of demonstrates the potential of optical diagnostics for electric field measurements across different states of matter and suggests improvements and new findings in the field.

Title of PhD thesis: . Supervisors: Sander Nijdam and Gustaaf Galein van Eden.