Development of the ion cyclotron emission diagnostic for the W7-X stellarator

Moseev, D.; Ochoukov, R.; Bobkov, V.; Dendy, R. O.; Faugel, H.; Hartmann, D.; Kallmeyer, J. P.; Lansky, J.; Laqua, H. P.; Marsen, S.; McClements, K. G.; Nielsen, S. K.; Reintrog, A.; Salewski, M.; Schmidt, B. S.; Schulz, T.; Stange, T.; Team, W X

doi:10.1063/5.0040944

Cited by 11 publications

(7 citation statements)

References 28 publications

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“…Increased NBI heating power along with a mix of ECRH should allow for higher ion temperatures to be achieved and to investigate the role of ECRH density pump-out. A growing set of fast ion diagnostics (an FC-FILD array [22], ion cyclotron emission [23], spectroscopic beam measurements [6], and collective Thomson scattering [24]) will allow for more detailed studies of the fast ion distribution function. This includes a program to perform fast ion phase space tomography.…”

Section: Discussionmentioning

confidence: 99%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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In the previous divertor campaign, the Wendelstein 7-X (W7-X) device injected 3.6 MW of neutral beam heating power allowing for the achievement of densities approaching 2 × 10 20 m −3 , and providing the first initial assessment of fast ion confinement in a drift optimized stellarator. The neutral beam injection (NBI) system on W7-X is comprised of two beam boxes with space for four radio frequency sources each. The 3.6 MW of heating reported in this work was achieved with two sources in the NI21 beam box. The effect of combined electron-cyclotron resonance heating (ECRH) and NBI was explored through a series of discharges varying both NBI and ECRH power. Discharges without ECRH saw a linear increase in the line-integrated plasma density, and strong peaking of the core density, over the

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Section: Discussionmentioning

confidence: 99%

First neutral beam experiments on Wendelstein 7-X

Team¹,

Lazerson²,

Ford³

et al. 2021

Nucl. Fusion

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“…W7-X was optimized to confine such particles, but up to date no validated experimental scenarios with these properties have been found. Under relevant experimental conditions, it also remains to show that the fastion confinement improves with increasing β. Lastly, new detectors have been installed in W7-X that measure ion-cyclotron emission (ICE) [20]. Parts of the physics associated with ICE may also be simulated with SCENIC in the future.…”

Section: Discussion and Summarymentioning

confidence: 99%

Simulation of radio-frequency heating and fast-ion generation in Wendelstein 7-X

Slaby

Machielsen

Lazerson

et al. 2022

J. Phys.: Conf. Ser.

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The next scientific operation phase of Wendelstein 7-X (W7-X) is scheduled to begin in late autumn of 2022 and will, for the first time, include experiments in which the ICRH (ion-cyclotron-resonance heating) antenna will be used. In addition to heating the plasma, this system will generate fast ions and thus offers a new way to assess fast-ion confinement in a stellarator such as W7-X. The first plasmas that will be used for the upcoming ICRH operation will be Helium-4 plasmas with a small Hydrogen minority on the order of about 10%. In tokamaks such plasmas typically offer good power absorption and are thus considered a safe way for gaining first experiences with the new antenna in W7-X. This assessment is confirmed by the SCENIC simulations carried out in this contribution that use profiles foreseen for the upcoming campaign as input. The simulations are carried out in the standard configuration of W7-X in low-beta (0.3% ≲ 〈β〉 ≲ 1%) plasmas. However, also scans over minority concentration and background-plasma density are performed. We find that the power absorbed by the Hydrogen minority directly from the radio-frequency wave is typically (provided that the minority concentration is not too high) on the order of about 90% with the rest going to the electrons. Very little power goes to the Helium-4 ions. Under the present simulation conditions only fast-ion energies up to about E ≈ 50 keV can be reached. Combining SCENIC and ASCOT simulations enables us to track lost particles through the scrape-off-layer to the 3D wall of W7-X and to compute wall loads caused by ICRH. The results show that the wall loads that can be expected from ICRH under the first operating conditions are benign.

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“…Ion Cyclotron Emission spectroscopy (ICE) has been tested in OP1 with a detector prototype integrated in an wall observation camera plugin. For OP2 polarization dependent measurements will be possible with a 4-sensor array attached to the plugin for CTS observation optics or using the ICRH antenna as another receiver [50].…”

Section: Fast Ion Diagnosticsmentioning

confidence: 99%

Core Diagnostics for WENDELSTEIN 7-X Steady-State Exploration Until 18 GJ

Hirsch

Bannmann

Beurskens

et al. 2022

Plasma and Fusion Research

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This contribution provides an overview of the core diagnostics as they are required for W7-X steady-state high-density operation with a divertor and profile control. The inferred profiles then address the stellarator optimization. A particular task is the characterization of fast ion slowing down and -losses, which in a classical stellarator reactor could result in unacceptable wall loads and ultimately are deleterious for the heating efficiency. The energy dissipated during operation, 10 MW • 1800 s impacts on the technical diagnostic realization via loads to in-vessel components, quasi steady-state operation requires adequate data acquisition and control systems.

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Development of the ion cyclotron emission diagnostic for the W7-X stellarator

Cited by 11 publications

References 28 publications

First neutral beam experiments on Wendelstein 7-X

First neutral beam experiments on Wendelstein 7-X

Simulation of radio-frequency heating and fast-ion generation in Wendelstein 7-X

Core Diagnostics for WENDELSTEIN 7-X Steady-State Exploration Until 18 GJ

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