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

Wendelstein 7-X Team; D. Moseev; I. Abramovic

doi:10.1088/1748-0221/15/05/C05035

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

Wendelstein 7-X Team, D. Moseev (Corresponding author), I. Abramovic

Science and Technology of Nuclear Fusion

Research output: Contribution to journal › Article › Academic › peer-review

4 Citations (SciVal)

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 language	English
Article number	C05035
Number of pages	13
Journal	Journal of Instrumentation
Volume	15
Issue number	5
DOIs	https://doi.org/10.1088/1748-0221/15/05/C05035
Publication status	Published - May 2020

Keywords

Detector modelling and simulations I (interaction of radiation with matter
etc)
interaction of hadrons with matter
interaction of photons with matter
interferometry
Plasma diagnostics
spectroscopy and imaging

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10.1088/1748-0221/15/05/C05035

Cite this

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title = "Collective Thomson Scattering Diagnostic for Wendelstein 7-X at 175 GHz",

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.",

keywords = "Detector modelling and simulations I (interaction of radiation with matter, etc), interaction of hadrons with matter, interaction of photons with matter, interferometry, Plasma diagnostics, spectroscopy and imaging",

author = "{Wendelstein 7-X Team} and D. Moseev and Laqua, {H. P.} and T. Stange and I. Abramovic and Nielsen, {S. K.} and S. {\"A}k{\"a}slompolo and K. Avramidis and H. Braune and G. Gantenbein and S. Illy and J. Jelonnek and J. Jin and W. Kasparek and L. Krier and Korsholm, {S. B.} and C. Lechte and A. Marek and S. Marsen and M. Nishiura and I. Pagonakis and M. Salewski and J. Rasmussen and A. Tancetti and M. Thumm and Wolf, {R. C.}",

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language = "English",

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AU - Wendelstein 7-X Team

AU - Moseev, D.

AU - Laqua, H. P.

AU - Stange, T.

AU - Abramovic, I.

AU - Nielsen, S. K.

AU - Äkäslompolo, S.

AU - Avramidis, K.

AU - Braune, H.

AU - Gantenbein, G.

AU - Illy, S.

AU - Jelonnek, J.

AU - Jin, J.

AU - Kasparek, W.

AU - Krier, L.

AU - Korsholm, S. B.

AU - Lechte, C.

AU - Marek, A.

AU - Marsen, S.

AU - Nishiura, M.

AU - Pagonakis, I.

AU - Salewski, M.

AU - Rasmussen, J.

AU - Tancetti, A.

AU - Thumm, M.

AU - Wolf, R. C.

PY - 2020/5

Y1 - 2020/5

N2 - 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.

AB - 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.

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KW - interaction of hadrons with matter

KW - interaction of photons with matter

KW - interferometry

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KW - spectroscopy and imaging

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DO - 10.1088/1748-0221/15/05/C05035

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JO - Journal of Instrumentation

JF - Journal of Instrumentation

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M1 - C05035

ER -

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

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Keywords

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