Collective Thomson scattering diagnostic at Wendelstein 7-X

Moseev, D.; Stejner, M.; Stange, T.; Abramovic, I.; Laqua, H. P.; Marsen, S.; Schneider, Nicholas M.; Braune, H.; Hoefel, U.; Kasparek, W.; Korsholm, S. B.; Lechte, C.; Leipold, F.; Nielsen, S. K.; Salewski, M.; Rasmussen, Jesper; Weissgerber, M.; Wolf, R. C.

doi:10.1063/1.5050193

Cited by 29 publications

(24 citation statements)

References 32 publications

(32 reference statements)

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“…The CTS system we have been and are developing and utilizing [9][10][11][12] all operate at frequencies between 60 GHz and 170 GHz. At these frequencies, the wavelengths allow for the use of ordinary aluminum foil as reflecting surface material.…”

Section: Prototypes Of Microwave Transmission Line Componentsmentioning

confidence: 99%

Fast production of microwave component prototypes by additive manufacturing and copper coating

Korsholm

Leipold

Madsen³

et al. 2021

Review of Scientific Instruments

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We present a novel method for efficient production of prototypes of microwave components by fused depositing modeling, also known as 3D plastic printing, and vapor deposition coating of a 1 μm copper layer. We demonstrate that the properties of the components follow the predicted performance for low power microwave propagation. The production method offers new opportunities for cheap and efficient production of mock-ups and prototypes of advanced-geometry components for tests with low-power microwaves.

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Section: Prototypes Of Microwave Transmission Line Componentsmentioning

confidence: 99%

Fast production of microwave component prototypes by additive manufacturing and copper coating

Korsholm

Leipold

Madsen³

et al. 2021

Review of Scientific Instruments

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“…The 140 GHz ECRH beams were also used for the collective Thomson scattering (CTS) [5]. Two scattering geometries were available.…”

Section: Collective Thomson Scatteringmentioning

confidence: 99%

Overview of W7-X ECRH Results

et al. 2019

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In its second operation phase (OP1.2a) W7-X was equipped with full 3d island divertor and an upgraded ECRH-system of 10 gyrotrons with a total port through power of 7 MW. The combination of pellet fueling and high density ECRH enabled to explore density above 1 1020 m-3. In particular with the O2-polarisation combined with a multi-pass reflector tile system a density of up to 1.4 1020 m-3 was achieved. At slightly lower densities high core beta values and record values of the fusion tripple product of 0.66 1020 m-3 keVs for stellarators were reached. In addition routine plasma start-up and ECRH wall conditioning were performed. The island divertor enables to demonstrate the intrinsic steady state capabilities of W7-X, where stationary discharges of up to 30s were demonstrated being only limited by the heat capacity of the uncooled divertor. With the flexible ECRH launch system current density profile variations were used for MHD stability investigations. Here by fine-tuning of the ECCD profile different MHD activity could be triggered.

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“…A CTS diagnostic for ion temperature measurements was installed and commissioned at the stellarator Wendelstein 7-X (W7-X). 4 For the probing beam of this CTS diagnostic, a gyrotron 5 of the Electron Cyclotron Resonance Heating (ECRH) system of W7-X, 6 which operates at 140 GHz, has been used. However, measurements in the plasma core at this frequency cannot be adequately accurate due to the absorption of the probe mm-wave beam and due to the high electron cyclotron emission (ECE) background, 7 which both deteriorate signal-to-noise ratio.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation on possible operation of a 140 GHz 1 MW gyrotron at 175 GHz for CTS plasma diagnostics at W7-X

et al. 2020

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Collective Thomson scattering is a common diagnostic technique for ion temperature measurements in experimental fusion plasma reactors. Such a system was successfully installed and commissioned at the Wendelstein 7-X stellarator. For this purpose, a 140 GHz gyrotron of the Electron Cyclotron Resonance Heating system was used as a source of the required probing millimeter (mm)-wave beam. However, accurate measurements in the plasma core were not possible at this heating frequency due to the absorption of the mm-waves and the high electron cyclotron emission background. To suppress these effects and to enhance the accuracy of the measurements, it is required to increase the frequency of the probing beam. In this work, the possibility to operate the same gyrotron, which has its nominal operation at 140 GHz, at a higher frequency is comprehensively investigated.

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Collective Thomson scattering diagnostic at Wendelstein 7-X

Cited by 29 publications

References 32 publications

Fast production of microwave component prototypes by additive manufacturing and copper coating

Fast production of microwave component prototypes by additive manufacturing and copper coating

Overview of W7-X ECRH Results

Theoretical investigation on possible operation of a 140 GHz 1 MW gyrotron at 175 GHz for CTS plasma diagnostics at W7-X

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