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V-band Doppler backscattering diagnostic in the TCV tokamak
P Molina Cabrera1, S Coda1, L Porte1
1Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland.
The Review of Scientific Instruments
|September 7, 2018
Summary
A new V-band Doppler back-scattering diagnostic enhances tokamak plasma measurements. It accurately maps magnetic-field pitch angles and rotation velocities, improving understanding of plasma behavior.
Area of Science:
- Plasma physics
- Fusion energy research
- Microwave diagnostics
Background:
- Tokamak devices require advanced diagnostics for plasma characterization.
- Understanding plasma dynamics, including magnetic field pitch angle and rotation, is crucial for fusion energy development.
Purpose of the Study:
- To detail the operational setup and capabilities of a novel V-band heterodyne Doppler back-scattering diagnostic for tokamak plasmas.
- To present initial data and validation of the diagnostic's performance.
Main Methods:
- Utilized a fast arbitrary waveform generator and vector network analyzer extension modules for mm-wave hardware.
- Employed a flexible quasi-optical launcher antenna for 3D beam steering and HE11 miter-bend polarizers for mode control.
- Applied ray-tracing simulations to determine the accessible k⊥ range and resolution.
Main Results:
- Successfully measured magnetic-field pitch angles at the plasma edge by analyzing backscattered signal power.
- Achieved a k⊥ range of 3-16 cm⁻¹ with 2-4 cm⁻¹ resolution.
- Perpendicular rotation velocity estimates showed good agreement with charge exchange recombination spectroscopy data.
Conclusions:
- The V-band diagnostic is a powerful tool for tokamak plasma research.
- The system's flexibility and accuracy enable detailed plasma physics studies.
- This diagnostic contributes to advancing fusion energy science.
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