Collective Thomson scattering system for determination of ion properties in a high flux plasma beam

Meiden, H.J. van der; Vernimmen, J.W.M.; Bystrov, K.; Jesko, K.; Kantor, M. Yu.; Temmerman, G. De; Morgan, T.W.

doi:10.1063/1.4973211

Cited by 18 publications

(19 citation statements)

References 24 publications

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“…Further possibilities to study plasmas relevant to detachment are offered by the Magnum-PSI linear plasma device, with a better diagnostic coverage. Target calorimetry and a newly installed bolometric diagnostic [49] could shed more light on studies of the power balance, while a collective Thomson scattering diagnostic [50] (under development) could give axial velocity information.…”

Section: Discussionmentioning

confidence: 99%

Studying divertor relevant plasmas in the Pilot-PSI linear plasma device: experiments versus modelling

Jesko¹,

Marandet²,

Bufferand³

et al. 2018

Plasma Phys. Control. Fusion

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Predictions for the operation of tokamak divertors are reliant on edge plasma simulations typically consisting of a fluid plasma code in combination with a Monte Carlo code for neutral species. Pilot-PSI is a linear device operating with a cascaded arc plasma source that produces plasmas comparable to those expected during the inter-ELM phase in the ITER divertor (T e ∼ 1 eV, n e ∼ 10 20 m −3). In this study, plasma discharges in Pilot-PSI have been modelled using the Soledge2D fluid plasma code [1] coupled to the Eirene neutral Monte Carlo code [2] in order to a) investigate which phenomena need to be included in the modeling to reproduce experimental trends and b) provide new insights to the interpretation of experiments. The simulations highlight the key role of ion/molecule elastic collisions in determining the ion flux reaching the target. Recombination is likely to play a role at high molecular background pressure. However, even with the most advanced atomic and molecular model used in this work, T e at the target is overestimated with respect to the measurements using TS and spectroscopy. T e in the simulations appears to saturate at 0.7 eV for a wide range of parameters, while experimentally values of 0.1-0.3 eV are found. As a consequence, in the simulations the volume recombination is underestimated, which is a strong function of T e when it is below 1 eV. Further analysis of simulation results using a two-point formalism shows that inelastic collisions between electrons and neutral background particles remove most of the energy 1 flux, mainly via dissociation of molecules and molecular ions. However this happens mostly in the upstream region of the beam where T e >1 eV. For T e <1 eV, there seems to be no significant energy removal mechanism in the simulated cases. The results also indicate that conclusions on the importance of volume processes, e.g. recombination, cannot be solely based on T e or the dominance of certain reaction rate coefficients over others, but rather the complete transport picture, including macroscopic flow, has to be taken into account. In the cases studied here, the plasma is typically advected to the wall too fast for recombination to remove a significant fraction of the particle flux.

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Section: Discussionmentioning

confidence: 99%

Studying divertor relevant plasmas in the Pilot-PSI linear plasma device: experiments versus modelling

Jesko¹,

Marandet²,

Bufferand³

et al. 2018

Plasma Phys. Control. Fusion

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“…The CTS diagnostic [4,10] was developed on the Pilot-PSI linear plasma generator (was shut down end 2015), the forerunner of Magnum-PSI (see Fig. 14).…”

Section: Cts In Pilot-psimentioning

confidence: 99%

“…The typical plasma conditions are a discharge current of 200 A, gas flow 2.5 slm and an axial magnetic field of 1.2 T to confine the plasma that interacts with a tungsten target located 560 mm downstream the source. The CTS laser system is equipped with a 10 Hz seeded laser (Continuum DLS 8000: pulse width of 7 ns FWHM, 1 J/pulse and linewidth 0.3 pm at 1064 nm) [4]. The location of the CTS scattering volume (beam waist * 0.8 mm) coincided with that of the standard incoherent TS system (532 nm, scattering angle 90°) [21].…”

Section: Cts In Pilot-psimentioning

confidence: 99%

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Incoherent and Collective Thomson Scattering for the Determination of Electron and Ion Properties in Low-Temperature Plasma

et al. 2020

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“…Single pulse TS has been applied successfully at Magnum-PSI during transient heat load experiments. A collective Thomson Scattering (CTS) system is being implemented on Magnum-PSI [6]. CTS shows the collective motion of the electrons, bunched in the Debye sphere of the ions, rather than the individual motion of the electrons, as in incoherent TS.…”

Section: Thomson Scattering Diagnosticsmentioning

confidence: 99%

Operational characteristics of the superconducting high flux plasma generator Magnum-PSI

Pol

Westen

Aussems

et al. 2018

Fusion Engineering and Design

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The interaction of intense plasma impacting on the wall of a fusion reactor is an area of high and increasing importance in the development of electricity production from nuclear fusion. In the Magnum-PSI linear device, an axial magnetic field confines a high density, low temperature plasma produced by a wall stabilized DC cascaded arc into an intense magnetized plasma beam directed onto a target. The experiment has shown its capability to reach conditions that enable fundamental studies of plasma-surface interactions in the regime relevant for fusion reactors such as ITER: 10 23-10 25 m-2 s-1 hydrogen plasma flux densities at 1-5 eV for tens of seconds by using conventional electromagnets. Recently the machine was upgraded with a superconducting magnet, enabling steady-state magnetic fields up to 2.5 T, expanding the operational space to high fluence capabilities for the first time. Also the diagnostic suite has been expanded by a new 4-channel resistive bolometer array and ion beam analysis techniques for surface analysis after plasma exposure of the target. A novel collective Thomson scattering system has been developed and will be implemented on Magnum-PSI. In this contribution, the current status, capabilities and performance of Magnum-PSI are presented.

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Collective Thomson scattering system for determination of ion properties in a high flux plasma beam

Cited by 18 publications

References 24 publications

Studying divertor relevant plasmas in the Pilot-PSI linear plasma device: experiments versus modelling

Studying divertor relevant plasmas in the Pilot-PSI linear plasma device: experiments versus modelling

Incoherent and Collective Thomson Scattering for the Determination of Electron and Ion Properties in Low-Temperature Plasma

Operational characteristics of the superconducting high flux plasma generator Magnum-PSI

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