Discharge initiation by ICRF antenna in IShTAR

Tripský, M.; Wauters, T.; D’Incà, R.; Crombé, Kristel; Jacquot, J.; Ochoukov, R.; Louche, F.; Usoltceva, M.; Kostic, A.; Lyssoivan, A.; Noterdaeme, Jean-Marie; Schoor, M. Van

doi:10.1051/epjconf/201715703056

Cited by 3 publications

(4 citation statements)

References 2 publications

(2 reference statements)

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“…The included electron collisions with background neutrals determine the occurrence of an electron multiplication avalanche. Rfdinity-1D reproduces TEXTOR [58], ASDEX Upgrade [59] and IShTAR experiments [60] and predicts successful plasma production with the ICRF antenna in ITER [61].…”

Section: Ion Cyclotron Wall Conditioning In Tokamaksmentioning

confidence: 99%

Wall conditioning in fusion devices with superconducting coils

Wauters¹,

Borodin

Brakel

et al. 2020

Plasma Phys. Control. Fusion

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Wall conditioning is essential in tokamak and stellarator research to achieve plasma performance and reproducibility. This paper presents an overview of recent conditioning results, both from experiments in present devices and modelling, in view of devices with superconducting coils, with focus on W7-X, JT-60SA and ITER. In these devices, the coils stay energised throughout an experimental day or week which demands for new conditioning techniques that work in presence of the nominal field, in addition to the proven conditioning methods such as baking, glow discharge conditioning (GDC) and low-Z wall coating through GDC-plasma, which do not work under such condition. The discussed techniques are RF conditioning without plasma current, both in the ion cyclotron and electron cyclotron range of frequencies, and diverted conditioning plasmas with nested magnetic flux surfaces.

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Section: Ion Cyclotron Wall Conditioning In Tokamaksmentioning

confidence: 99%

Wall conditioning in fusion devices with superconducting coils

Wauters¹,

Borodin

Brakel

et al. 2020

Plasma Phys. Control. Fusion

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“…An analytical method was developed in order to pre-assess the optimal parameters for discharge initiation by ICRF antennas [61]. The method complements the self-consistent but CPU intensive simulations by the Particle-in-Cell Monte Carlo Collision code RFdinity1D [62]. It builds on the ponderomotive description of electron acceleration in the vacuum parallel electric field E // (z, t).…”

Section: Icrf Assisted Plasma Start-up and Wall Conditioningmentioning

confidence: 99%

Ion cyclotron resonance heating scenarios for DEMO

Eester¹,

Lerche²,

Ragona³

et al. 2019

Nucl. Fusion

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The present paper offers an overview of the potential of ion cyclotron resonance heating (ICRH) or radio frequency (RF) heating for the DEMO machine. It is found that various suitable heating schemes are available. Similar to ITER and in view of the limited bandwidth of about 10M Hz that can be achieved to ensure optimal functioning of the launcher, it is proposed to make core second harmonic tritium heating the key ion heating scheme, assisted by fundamental cyclotron heating 3 He in the early phase of the discharge; for the present design of DEMO-with a static magnetic field strength of B o = 5.855T-that places the T and 3 He layers in the core for f = 60M Hz and suggests to center the bandwidth around that main operating frequency. In line with earlier studies for hot, dense plasmas in large-size magnetic confinement machines it is shown that good single pass absorption is achieved but that the size as well as operating density and temperature of the machine cause the electrons to absorb a non-negligible fraction of the power away from the core when core ion heating is aimed at. Current drive and alternative heating options are briefly discussed and a dedicated computation is done for the traveling wave antenna, proposed for DEMO in view of its compatibility with substantial antenna-plasma distances. The various tasks that ICRH can fulfill are briefly listed. Finally, the impact of transport and the sensitivity of the obtained results to changes in the machine parameters is commented on.

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“…Second, the physics of plasma breakdown with ICRF antennas is still not completely understood. And third, the parallel electric field used for the breakdown is the same that creates the RF sheath: it may be difficult to disentangle both phenomena [10].…”

Section: Design and Setupmentioning

confidence: 99%

“…The plasma source is based on the concept of ionisation by helicon waves, which offer the possibility for large volumes to reach high densities (10 18 m −3 and above) with uniform radial profiles [10][11][12]. The price for this objective is the high level of injected power (several kW), which can lead to dramatic damages if the flow of the power in the source is not controlled.…”

Section: External Plasma Sourcementioning

confidence: 99%

A Test Facility to Investigate Sheath Effects during Ion Cyclotron Resonance Heating

Crombé¹,

Inca²,

Faudot³

et al. 2019

Plasma Science and Technology - Basic Fundamentals and Modern Applications

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Nuclear fusion is a promising candidate to supply energy for future generations. At the high temperatures needed for the nuclei to fuse, ions and electrons are no longer bound into atoms. Magnetic fields confine the resulting plasma. One of the heating methods is the ion cyclotron resonant absorption of waves emitted by an external Ion Cyclotron Radio Frequency (ICRF) antenna. The efficiency of ICRF heating is strongly affected by rectified RF electric fields at antenna and other in-vessel components (so-called 'sheath effects'). The chapter presents an overview of ICRF principles. Attention is given to characterising the detrimental sheath effects through experiments on a dedicated test facility (IShTAR: Ion cyclotron Sheath Test ARrangement). IShTAR has a linear magnetic configuration and is equipped with an independent helicon plasma source. The configuration and capabilities of the test-bed and its diagnostics are described, as well as an analysis of the plasmas.

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Discharge initiation by ICRF antenna in IShTAR

Cited by 3 publications

References 2 publications

Wall conditioning in fusion devices with superconducting coils

Wall conditioning in fusion devices with superconducting coils

Ion cyclotron resonance heating scenarios for DEMO

A Test Facility to Investigate Sheath Effects during Ion Cyclotron Resonance Heating

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