Millimeter-Wave Beam Scattering by Field-Aligned Blobs in Simple Magnetized Toroidal Plasmas

Area of Science:

• Plasma physics
• Wave-plasma interactions
• Millimeter-wave diagnostics

Background:

• Understanding plasma behavior is crucial for fusion energy and space physics.
• Plasma blobs significantly impact wave propagation.
• Direct experimental data on millimeter-wave scattering by plasma blobs are scarce.

Purpose of the Study:

• To conduct the first direct experimental measurements of millimeter-wave scattering by plasma blobs.
• To investigate the relationship between electron density fluctuations and transmitted power.
• To validate a first-principles full-wave model against experimental observations.

Main Methods:

• Utilizing a simple magnetized torus for plasma generation.
• Employing millimeter-wave beams with wavelengths comparable to plasma blob sizes.
• Conducting in-situ Langmuir probe measurements for electron density diagnostics.

Main Results:

• Direct experimental measurements of millimeter-wave scattering by plasma blobs were successfully obtained.
• Electron density fluctuations were shown to induce correlated fluctuations in transmitted millimeter-wave power.
• A first-principles full-wave model accurately predicted experimental results using 2D electron density profiles.

Conclusions:

• The study provides the first direct experimental validation of millimeter-wave scattering by plasma blobs.
• The developed full-wave model is a reliable tool for predicting wave propagation in plasmas with density fluctuations.
• These findings advance the understanding of wave-plasma interactions in magnetized toroidal systems.