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The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements

The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements

Published on: December 5, 2025

Microwave Doppler reflectometer system in LHD.

T Tokuzawa¹, A Ejiri, K Kawahata

¹National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Japan. tokuzawa@nifs.ac.jp

The Review of Scientific Instruments

|November 7, 2012

Summary

This summary is machine-generated.

A new Doppler reflectometer was developed for the Large Helical Device (LHD) to measure poloidal rotation velocity. The system successfully obtained Doppler shifted signals consistent with other measurement techniques.

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Area of Science:

Plasma physics
Fusion energy research

Background:

Accurate measurement of plasma rotation is crucial for understanding plasma confinement in fusion devices.
Previous methods for measuring poloidal rotation velocity in the Large Helical Device (LHD) had limitations.

Purpose of the Study:

To develop and implement a Doppler reflectometer system for measuring poloidal rotation velocity in the LHD.
To validate the performance of the new system against established diagnostic techniques.

Main Methods:

Development and installation of a Doppler reflectometer within the LHD vacuum vessel.
Utilized a synthesizer as the microwave source, operating in the ka-band and V-band frequency ranges.
Incorporated a remotely controlled antenna tilting system for precise measurements.

Main Results:

Successfully obtained Doppler shifted signals using the developed reflectometer.
The measurements of poloidal rotation velocity were consistent with data obtained from Charge Exchange Recombination Spectroscopy (CXRS).

Conclusions:

The newly developed Doppler reflectometer is a viable tool for measuring poloidal rotation velocity in the LHD.
The system's performance validates its utility for future plasma diagnostics and research in fusion devices.