Plasma electron density measurement by a digital signal processor based millimetre-wave interferometer
Abstract
This paper addresses the measurement of the average plasma electron density based on the measurement of a phase, using a 2 mm wavelength single-channel digital millimetre-wave interferometer in the Damavand tokamak. Damavand tokamak discharges have plasma currents up to 40 kA with discharge duration greater than 15 ms and toroidal magnetic fields up to 1.2 T. Phase analysis is done using a digital signal processor which is capable of registering phase variations at a rate of 10pgr × 104 rad s-1, which corresponds to a change in electron density of 1.5 × 1017 cm-3 s-1. In this paper, the details of the millimetre wave interferometer system along with the implementation of a phase measurement routine based on a TMS320c25 digital signal processor are presented.
- Publication:
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Measurement Science and Technology
- Pub Date:
- May 2004
- DOI:
- 10.1088/0957-0233/15/5/032
- Bibcode:
- 2004MeScT..15.1000E
- Keywords:
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- plasma electron densitydiagnosticmillimetre-wave interferometertokamakdigital signal processing