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Related Experiment Video

Updated: Feb 3, 2026

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Microwave frequency comb Doppler reflectometer applying fast digital data acquisition system in LHD.

T Tokuzawa¹, H Tsuchiya¹, T Tsujimura¹

¹National Institutes of Natural Sciences, National Institute for Fusion Science, Toki 509-5292, Japan.

The Review of Scientific Instruments

|November 8, 2018

Summary

This summary is machine-generated.

Researchers enhanced microwave frequency comb Doppler reflectometry by increasing radial observation points to 45 using high-speed digital signal processing. This improved system accurately measures perpendicular velocity profiles, aligning with E × B drift velocity.

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Area of Science:

Plasma physics
Microwave diagnostics
Doppler reflectometry

Background:

Accurate measurement of plasma properties is crucial for understanding fusion energy.
Doppler reflectometry is a key diagnostic technique for plasma velocity estimation.
Existing systems have limitations in radial resolution.

Purpose of the Study:

To enhance the radial resolution of microwave frequency comb Doppler reflectometry.
To develop and validate a new data acquisition and signal processing scheme.
To investigate the radial profile of perpendicular velocity in plasma.

Main Methods:

Utilized a high sampling rate of 40 GS/s digital signal processing.
Developed a new Doppler shifted frequency estimation scheme.
Compared the new estimation scheme with conventional techniques.

Main Results:

Increased radial observation points from 8 to 20, and up to 45.
Obtained a fine radial profile of perpendicular velocity.
Demonstrated consistency between measured perpendicular velocity and E × B drift velocity.

Conclusions:

The enhanced microwave frequency comb Doppler reflectometer system significantly improves radial resolution.
The new system provides accurate measurements of plasma perpendicular velocity profiles.
The findings validate the system's capability for detailed plasma diagnostics.