Development of terahertz laser diagnostics for electron density measurements

Area of Science:

• Plasma physics
• Laser diagnostics
• Fusion energy research

Background:

• Terahertz laser interferometry is crucial for diagnosing high-performance plasma devices.
• Future fusion devices like ITER require advanced diagnostic tools for plasma characterization.

Purpose of the Study:

• To develop a two-color laser interferometer using terahertz laser sources for advanced fusion plasma experiments.
• To investigate terahertz laser sources for high-power, simultaneous oscillations.
• To present recent progress in terahertz laser diagnostics, including vibration compensation and beam transmission.

Main Methods:

• Utilizing a continuous-wave 9R(8) CO(2) laser to pump a CH(3)OD laser.
• Achieving simultaneous oscillations at 57.2 and 47.6 microm wavelengths.
• Investigating mechanical vibration compensation using two-color laser operation.
• Examining terahertz laser beam transmission through a dielectric waveguide.

Main Results:

• High-power simultaneous oscillations of a CH(3)OD laser at 57.2 and 47.6 microm were achieved.
• The optimal terahertz laser wavelength around 50 microm was determined for fusion devices, considering beam refraction and signal-to-noise ratio.
• Progress in mechanical vibration compensation and dielectric waveguide transmission for terahertz laser diagnostics was demonstrated.

Conclusions:

• The developed two-color terahertz laser interferometer shows promise for high-performance operation in large helical devices and future burning plasma experiments.
• Simultaneous dual-wavelength terahertz laser operation is a viable technique for improving plasma diagnostic accuracy.
• Further development in terahertz laser diagnostics will enhance the understanding and control of fusion plasmas.