Comparison of the performance of different options for the ITER ECRH Upper Launcher

Zohm, H.; Heidinger, R.; Henderson, M.; Poli, E.; Ramponi, G.; Saibene, G.; Verhoeven, A.G.A.

doi:10.1088/1742-6596/25/1/028

Cited by 34 publications

(34 citation statements)

References 4 publications

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“…The requirement for ITER has been estimated based on experimental data both for the (3/2) and the (2/1)-NTM to η NT M ≥ 1.2 for large β at the onset compared to the marginal β marg , i.e. β N >> β N,marg [25]. This translates for the island size W into W sat ≈ W onset >> W marg .…”

Section: Stabilization Of Excited Ntmsmentioning

confidence: 99%

Control of neoclassical tearing modes

Maraschek

2012

Nucl. Fusion

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Abstract. Neoclassically driven tearing modes (NTM) are a major problem for tokamaks operating in a conventional ELMy H-mode scenario. Depending on the mode numbers these pressure driven perturbations cause a mild reduction of the maximum achievable β N = β t /() before the onset of the NTM, or can even lead to disruptions at low edge safety factor, q 95 . A control of this type of modes in high β N plasmas is therefore of vital interest for magnetically confined fusion plasmas. The control consists of two major approaches, namely the control of the excitation of these modes and the removal, or at least mitigation, of these modes, once an excitation could not be avoided. For both routes examples will be given and the applicability of these approaches to ITER will be discussed.

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Section: Stabilization Of Excited Ntmsmentioning

confidence: 99%

Control of neoclassical tearing modes

Maraschek

2012

Nucl. Fusion

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“…During the last few years, detailed beam tracing calculations in support of the EC upper launcher design have been carried by means of two beam tracing codes, GRAY [1] and TORBEAM [2] to evaluate the performance of the upper launcher for its main goal of NTM stabilization, for a number of different mm-wave designs proposed for the Remote Steering (RS) and the Front Steering (FS) launcher options, as part of EFDA technology tasks. [3,4]. The requirement for a large steering of the poloidal injection angle (~21 0 ) to cope with the expected variation of the radial location of the q=2 and q=3/2 surfaces (0.65≤ρ p ≤0.93), ρ p being the square root of the normalized poloidal flux) in a number of ITER scenarios relevant for NTMs, as well as that of injecting well focused beams with a waist close to the plasma, have been shown to be crucial items for the mm-wave optimization.…”

Section: Introductionmentioning

confidence: 99%

ITER ECRH-ECCD System Capabilities for Extended Physics Applications

Ramponi¹,

Farina²,

Henderson

et al. 2007

Fusion Science and Technology

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The ability of the ITER Electron Cyclotron Wave launchers of driving localized current at various plasma locations is analyzed by means of beam tracing codes, looking at extended physics application of ECCD in ITER and at possible synergy between the two launchers. Calculations for an improved design of the Upper launcher, based on four upper ports and front steering mirrors allowing both optimum focusing of the beams and an extended plasma deposition region, show that narrow, high peak current density profiles may be maintained over the radial range 0.4≤ρ p ≤0.9. Calculations for the Equatorial launcher, where the control of the deposition location is achieved by varying the toroidal injection angle β, point out that, due to poor localization and incomplete power absorption at large toroidal angles (β>40 0 ), the power deposition and current drive location by this launcher is limited to ρ≤0.55. Moreover it is shown that performances close to the center can be improved with a poloidal tilt of the low and top front mirrors. The main aim of this study is to provide guidance to the design of both launchers in order to optimize their performances, depending on the physics application.

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“…In order to fulfill extended physics requirements to include ELM control and CD [4][5][6], the beam steering range should be increased to ± 20˚ (± 10˚ at steering mirror). Optimal beam focusing at deposition location allows to increase the overall peformance and reliability margin of the ECCD through higher j CD /j BS values, since failure of a number of beam lines can be tolerated while still achieving full NTM stabilization.…”

Section: A Steering Mechanism Requirementsmentioning

confidence: 99%

A frictionless steering mechanism for the Front Steering ECCD ITER Upper Port Launcher

Sánchez

Bertizzolo

Chavan

et al. 2005

21st IEEE/NPS Symposium on Fusion Engineering SOFE 05

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Abstract-A FS launcher is being designed for the ITER upper port, which offers enhanced physics performance over the RS launcher. A two mirror system is used to decouple the focusing and steering aspects of the launcher and provide a relatively small beam waist (<20mm) projected far into the plasma (>1.6m from the steering mirror). The resulting NTM stabilization efficiency (maximum CD density divided by the local bootstrap current > 1.6) is above marginal for the q=2 and 3/2 rational flux surfaces of the relevent ITER equilibria (scenarios 2, 3a and 5) and a factor of ~3 relative to an equivalent RS launcher. The performance of the FS launcher strongly depends on the reliability of the steering mechanism, which is used to rotate the plasma facing steering mirror. CRPP has designed a frictionless steering mechanism assembled in a compact cartridge capable of up to ±7˚ rotation (corresponding to a poloidal steering range of up to ±14˚ for the microwave beam around a fixed axis of rotation) that offers a high operation reliability despite the close proximity to the thermal and neutron flux coming from the ITER plasma.

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Comparison of the performance of different options for the ITER ECRH Upper Launcher

Cited by 34 publications

References 4 publications

Control of neoclassical tearing modes

Control of neoclassical tearing modes

ITER ECRH-ECCD System Capabilities for Extended Physics Applications

A frictionless steering mechanism for the Front Steering ECCD ITER Upper Port Launcher

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