Working Paper Article Version 1 This version is not peer-reviewed

Online Plasma Measurement Using the TJ-II FPGA-based IR Interferometer

Version 1 : Received: 19 September 2019 / Approved: 20 September 2019 / Online: 20 September 2019 (10:32:16 CEST)

How to cite: Esteban, L.; Regadio, A. Online Plasma Measurement Using the TJ-II FPGA-based IR Interferometer. Preprints 2019, 2019090235 Esteban, L.; Regadio, A. Online Plasma Measurement Using the TJ-II FPGA-based IR Interferometer. Preprints 2019, 2019090235

Abstract

Interferometry is used in magnetic fusion devices to measure the line-1 averaged electron density. It is based on detecting changes in the refractive index of electromagnetic waves traveling through a plasma. The adequate frequency of these electromagnetic waves depends on several limitations. First the maximum expected peak electronic density must be lower than the cutoff density for that frequency. This means that the waves can still propagate through the plasma when the maximum density is reached. In this sense, IR interferometers operating in the infrared región are themost suitable. With such low wavelengths, mechanical vibrations become an important issue and a complementary interferometer to cancel these vibrations must be used. These arrangements are called two color interferometers. In this paper some measurements that were obtained from the TJ-II double color IR FPGA-based processing system that were never published before are shown and analyzed. The line-averaged electron density is computed in real time (100 μs).

Subject Areas

magnetic fusion devices; ir interferometry; fpga; phase detection; dsp

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