Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz

Dmitry Moseev*, H. P. Laqua, T. Stange, I. Abramovic, S. K. Nielsen, S. Äkäslompolo, K. Avramidis, H. Braune, G. Gantenbein, S. Illy, J. Jelonnek, J. Jin, W. Kasparek, L. Krier, S.B. Korsholm, C. Lechte, Ales Marek, S. Marsen, M. Nishiura, I. PagonakisM. Salewski, J. Rasmussen, A. Tancetti, M. Thumm, R. C. Wolf

*Corresponding author for this work

Research output: Contribution to journalConference articleResearchpeer-review

Abstract

The Collective Thomson Scattering (CTS) diagnostic measures the scattering spectrum of incident radiation off collective fluctuations in plasmas. In Wendelstein 7-X (W7-X) the diagnostic uses a 140 GHz heating gyrotron as a source of the probing radiation. At this frequency, the CTS spectra are heavily affected by the electron cyclotron emission, and the microwave beam propagation is restricted at typical W7-X plasma parameters. The diagnostic was successfully commissioned in the last experimental campaign and demonstrated ion temperature measurements. However, the signal-to-noise ratio was too low for measuring other quantities such as the fast-ion velocity distribution function or the fuel ion ratio. Currently, the W7-X CTS diagnostic is undergoing an upgrade to a frequency of 175 GHz. This will increase the sensitivity of the diagnostic, since the noise due to electron cyclotron emission will be reduced, and it will relax the constraints on microwave beam propagation in W7-X. Here we present the salient features of the upgraded CTS system and discuss its prospects for both thermal-ion and fast-ion measurements.
Original languageEnglish
Article numberC05035
JournalJournal of Instrumentation
Volume15
Issue number5
Number of pages13
ISSN1748-0221
DOIs
Publication statusPublished - 2020
Event19th International Symposium on Laser-Aided Plasma Diagnostics 2019 - Whitefish, United States
Duration: 22 Sep 201926 Sep 2019
Conference number: 19

Conference

Conference19th International Symposium on Laser-Aided Plasma Diagnostics 2019
Number19
CountryUnited States
CityWhitefish
Period22/09/201926/09/2019

Cite this

Moseev, D., Laqua, H. P., Stange, T., Abramovic, I., Nielsen, S. K., Äkäslompolo, S., Avramidis, K., Braune, H., Gantenbein, G., Illy, S., Jelonnek, J., Jin, J., Kasparek, W., Krier, L., Korsholm, S. B., Lechte, C., Marek, A., Marsen, S., Nishiura, M., ... Wolf, R. C. (2020). Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz. Journal of Instrumentation, 15(5), [C05035]. https://doi.org/10.1088/1748-0221/15/05/C05035