Intermediate frequency band digitized high dynamic range radiometer system for plasma diagnostics and real-time Tokamak control

Bongers, WA.; Van Beveren, V.; Thoen, D.J.; Nuij, P.J.W.M.; De Baar, M.R.; Donné, A.J.H.; Westerhof, E.; Goede, A.P.H.; Krijger, B.; Van den Berg, M.A.; Kantor, M.; Graswinckel, M.F.; Hennen, B.A.; Schüller, F.C.

doi:doi:10.1063/1.3594101

Intermediate frequency band digitized high dynamic range radiometer system for plasma diagnostics and real-time Tokamak control

Title

Intermediate frequency band digitized high dynamic range radiometer system for plasma diagnostics and real-time Tokamak control

Author

Bongers, WA.
Van Beveren, V.
Thoen, D.J.
Nuij, P.J.W.M.
De Baar, M.R.
Donné, A.J.H.
Westerhof, E.
Goede, A.P.H.
Krijger, B.
Van den Berg, M.A.
Kantor, M.
Graswinckel, M.F.
Hennen, B.A.
Schüller, F.C.

Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Date

2011-06-24

Abstract

An intermediate frequency (IF) band digitizing radiometer system in the 100–200 GHz frequency range has been developed for Tokamak diagnostics and control, and other fields of research which require a high flexibility in frequency resolution combined with a large bandwidth and the retrieval of the full wave information of the mm-wave signals under investigation. The system is based on directly digitizing the IF band after down conversion. The enabling technology consists of a fast multi-giga sample analog to digital converter that has recently become available. Field programmable gate arrays (FPGA) are implemented to accomplish versatile real-time data analysis. A prototype system has been developed and tested and its performance has been compared with conventional electron cyclotron emission (ECE) spectrometer systems. On the TEXTOR Tokamak a proof of principle shows that ECE, together with high power injected and scattered radiation, becomes amenable to measurement by this device. In particular, its capability to measure the phase of coherent signals in the spectrum offers important advantages in diagnostics and control. One case developed in detail employs the FPGA in real-time fast Fourier transform (FFT) and additional signal processing. The major benefit of such a FFT-based system is the real-time trade-off that can be made between frequency and time resolution. For ECE diagnostics this corresponds to a flexible spatial resolution in the plasma, with potential application in smart sensing of plasma instabilities such as the neoclassical tearing mode (NTM) and sawtooth instabilities. The flexible resolution would allow for the measurement of the full mode content of plasma instabilities contained within the system bandwidth.

Subject

analogue-digital conversion
fast Fourier transforms
logic arrays
plasma diagnostics
plasma inertial confinement
radiometers
sawtooth instability
tearing instability
Tokamak devices

To reference this document use:

http://resolver.tudelft.nl/uuid:4433a016-8862-4d1c-92a0-26ecce8df439

DOI

https://doi.org/10.1063/1.3594101

Publisher

American Institute of Physics

ISSN

0034-6748

Source

http://link.aip.org/link/doi/10.1063/1.3594101