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Systematic comparison between line integrated densities measured with interferometry and polarimetry at JET
1Consorzio RFX, Associazione EURATOM-Enea Sulla Fusione, Corso Stati Uniti 4, I-35127 Padova, Italy.
The Review of Scientific Instruments
|July 4, 2009
Summary
Polarimetry offers a reliable method for measuring electron density, matching interferometry results closely. This technique can recover data during interferometry fringe jumps, aiding real-time plasma control.
Area of Science:
- Plasma physics
- Fusion energy research
Background:
- Interferometry is a standard method for measuring line-integrated electron density in fusion devices.
- Fringe jumps in interferometry can disrupt real-time plasma control.
Purpose of the Study:
- To systematically compare electron density measurements from interferometry and polarimetry at JET.
- To assess the reliability of Cotton-Mouton effect measurements for electron density determination.
- To evaluate polarimetry's potential to substitute or complement interferometry, especially during fringe jumps.
Main Methods:
- Systematic comparison of line-integrated electron density data from interferometry and polarimetry.
- Analysis of Cotton-Mouton effect measurements across a range of plasma parameters.
- Study of electron density recovery using polarimetric data during interferometric fringe jumps.
Main Results:
- High agreement (within one fringe, 1.143 x 10^19 m^-2) between interferometry and polarimetry for over 90% of measurements.
- Demonstrated reliability of Cotton-Mouton effect measurements for electron density.
- Successful recovery of interferometric data using polarimetry during simulated fringe jumps.
Conclusions:
- Polarimetry is a viable and satisfactory alternative to interferometry for electron density measurements.
- Polarimetry can effectively compensate for interferometric fringe jumps, improving real-time experimental control.
- This dual-method approach enhances the robustness of electron density diagnostics in fusion experiments.
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