The optimization of resonant magnetic perturbation spectra for the COMPASS tokamak

Cahyna, P.; Pánek, R.; Fuchs, V.; Krlín, L.; Bécoulet, M.; Huysmans, G.; Nardon, E.

doi:10.1088/0029-5515/49/5/055024

Cited by 14 publications

(18 citation statements)

References 20 publications

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“…Next, a minor modulation in plasma position due to the feedback system properties proved to produce a well correlated eect between HXR radiation and infrared radiation from the limiter, which directly conrmed that RE interaction with the limiter makes a signicant contribution to the overall HXR radiation intensity [33]. In this subsection, the main results from recent RE experiments with RMP system at COMPASS [52,53] are presented. The work was partly inspired by recent work of the ASDEX Upgrade team in RMP experiments on post-disruption RE beam [54].…”

Section: Re In Perturbed Magnetic Eldsmentioning

confidence: 98%

Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research

Mlynář

Ficker

Macúšová

et al. 2018

Plasma Phys. Control. Fusion

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The role of the COMPASS tokamak in research of generation, connement and losses of Runaway Electron (RE) population is presented. Recently, two major groups of experiments aimed at improved understanding and control of the REs have been pursued. First, the eects of the Massive Gas Injection (MGI, ∼ 10 21 Ar/Ne particles) and impurity seeding (∼ 10 18 particles) were studied systematically. The observed phenomena include generation of the post-disruption RE beam and current conversion from plasma to RE. Zero loop voltage control was implemented in order to study the decay in simplied conditions. A distinctive drop of background plasma temperature and electron density was observed following an additional deuterium injection into the RE beam. The loop voltage control the parametric dependence of the current decay rate dI/dt can be studied systematically and possibly extrapolated to larger RE experiments at COMPASS in support of the EUROfusion research 2 facilities. Second, recent results of experiments focused on the role of the magnetic eld in physics of RE were analysed. In this contribution, special attention is given to the observed eects of the Resonant Magnetic Perturbation (RMP) on the RE population. The benets of the RE experiments on COMPASS was reinforced by diagnostic enhancements (fast cameras, Cherenkov detector, vertical ECE etc.) and modelling eorts (in particular, coupling of the METIS and LUKE codes).

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Section: Re In Perturbed Magnetic Eldsmentioning

confidence: 98%

Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research

Mlynář

Ficker

Macúšová

et al. 2018

Plasma Phys. Control. Fusion

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“…An example of the laminar plot and the stable manifold is shown on Figure 1 (left plot) for an equilibrium predicted for the COMPASS tokamak [21] in the case of a magnetic field of 1.2 T, low triangularity, singlenull (SND) geometry and heating by one co-injected neutral beam [22]. The n = 2 perturbation is imposed by the existing perturbation coils whose description can be found in [23].…”

Section: Modelling and Theoretical Understanding Of The Strike-point ...mentioning

confidence: 99%

Model for screening of resonant magnetic perturbations by plasma in a realistic tokamak geometry and its impact on divertor strike points

Cahyna

Nardon

2011

Journal of Nuclear Materials

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This work addresses the question of the relation between strike-point splitting and magnetic stochasticity at the edge of a poloidally diverted tokamak in the presence of externally imposed magnetic perturbations. More specifically, ad-hoc helical current sheets are introduced in order to mimic a hypothetical screening of the external resonant magnetic perturbations by the plasma. These current sheets, which suppress magnetic islands, are found to reduce the amount of splitting expected at the target, which suggests that screening effects should be observable experimentally. Multiple screening current sheets reinforce each other, i.e. less current relative to the case of only one current sheet is required to screen the perturbation.

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“…The COMPASS tokamak is a compact-sized (R = 0.56 m, a = 0.2 m) experimental device of an ITER-like cross section, operated in a diverted plasma regime [13] (for more information about the discharge parameters used in this work, see section 4.2). Its RMP coil system consists of a series of independent ex-vessel conductors that cover the whole vacuum chamber and can be connected into a variable saddle coil configuration [14]. This offers a unique variability of the poloidal mode number m spectrum of the generated RMP.…”

Section: Rmp Field Generation In the Compass Tokamakmentioning

confidence: 99%

Measurements and modelling of plasma response field to RMP on the COMPASS tokamak

et al. 2016

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It has been shown on several tokamaks that application of a resonant magnetic perturbation (RMP) field to the plasma can lead to suppression or mitigation of edge-localized mode (ELM) instabilities. Due to the rotation of the plasma in the RMP field reference system, currents are induced on resonant surfaces within the plasma, consequently screening the original perturbation. In this work, the extensive set of 104 saddle loops installed on the COMPASS tokamak is utilized to measure the plasma response field for two n = 2 RMP configurations of different poloidal mode m spectra. It is shown that spatially the response field is in opposite phase to the original perturbation, and that the poloidal profile of the measured response field does not depend on the poloidal profile of the applied RMP. Simulations of the plasma response by the linear MHD code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) reveal that both of the studied RMP configurations are well screened by the plasma. Comparison of measured plasma response field with the simulated one shows a good agreement across the majority of poloidal angles, with the exception of the midplane low-field side area, where discrepancy is seen.

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The optimization of resonant magnetic perturbation spectra for the COMPASS tokamak

Cited by 14 publications

References 20 publications

Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research

Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research

Model for screening of resonant magnetic perturbations by plasma in a realistic tokamak geometry and its impact on divertor strike points

Measurements and modelling of plasma response field to RMP on the COMPASS tokamak

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