Design of a dispersion interferometer on a field-reversed configuration device

Area of Science:

• Plasma physics
• Optical diagnostics

Background:

• Dispersion interferometry (DI) is a key technique for plasma density measurement.
• Traditional interferometers face challenges with mechanical vibrations and fringe jump errors.
• The Huazhong University of Science and Technology field-reversed configuration (HFRC) device requires advanced diagnostics for its high electron density (10^20 m^-3).

Purpose of the Study:

• To develop and test a Dispersion Interferometry system for the HFRC device.
• To achieve high temporal resolution for density fluctuation measurements.
• To validate the performance of key optical components, including nonlinear crystals.

Main Methods:

• Utilizing a CO2 laser-based Dispersion Interferometry system.
• Implementing a heterodyne technique with an acousto-optic modulator for enhanced temporal resolution.
• Testing nonlinear optical elements, specifically AgGaSe2 crystals, for second harmonic generation.

Main Results:

• The DI system is designed to be immune to mechanical vibrations and avoids fringe jump errors.
• A temporal resolution of 40 MHz is achieved, enabling MHz-range density fluctuation measurements.
• AgGaSe2 crystals demonstrated efficient second harmonic generation (52.5 µW at 10 W incident CO2 power).

Conclusions:

• The developed Dispersion Interferometry system is suitable for density measurements on the HFRC device.
• The system's design offers advantages in simplicity and robustness compared to traditional methods.
• Successful testing of optical components paves the way for the operational DI system on the HFRC device.