Visible charge exchange spectroscopy at JET

Hellermann, M. G. von; Mandl, W.; Summers, H. P.; Weisen, H.; Boileau, A.; Morgan, P. D.; Morsi, H. W.; Koenig, R.; Stamp, M.; Wolf, R. C.

doi:10.1063/1.1141975

Cited by 81 publications

(49 citation statements)

References 9 publications

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“…Apart from the standard data routinely available in JET, the main diagnostics used for the studies reported here were the ECE heterodyne radiometer (KK3) [8] and CXRS (KS5) [9] for electron and ion temperature measurements, respectively, and the horizontal (KR2) and vertical (KF1) neutral particle analysers (NPAs) [10,11] for the assessment of fast ion tails eventually created due to ICRF acceleration. The latter were complemented by measurements of fast ion losses performed with the scintillator probe KA3 [12].…”

Section: Experimental Set-upmentioning

confidence: 99%

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Lerche¹,

Eester²,

Johnson³

et al. 2012

Plasma Phys. Control. Fusion

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Two ion cyclotron range of frequencies (ICRF) heating schemes proposed for the half-field operation phase of ITER in hydrogen plasmas-fundamental H majority and second harmonic 3 He ICRF heating-were recently investigated in JET. Although the same magnetic field and RF frequencies (f ≈ 42 MHz and f ≈ 52 MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Unlike for the well-performing H minority heating scheme to be used in 4 He plasmas, modest heating efficiencies (η = P absorbed /P launched < 40%) with dominant electron heating were found in both H plasma scenarios studied, and enhanced plasma-wall interaction manifested by high radiation losses and relatively large impurity content in the plasma was observed. This effect was stronger in the 3 He ICRF heating case than in the H majority heating experiments and it was verified that concentrations as high as ∼20% are necessary to observe significant ion heating in this case. The RF acceleration of the heated ions was modest in both cases, although a small fraction of the 3 He ions reached about 260 keV in the second harmonic 3 He heating experiments when 11 Romanelli F et al 2010 Proc. 23rd IAEA Fusion Energy Conf. (Daejeon, Korea, 2010 5 MW of ICRF power was applied. Considerable RF acceleration of deuterium beam ions was also observed in some discharges of the 3 He heating experiments (where both the second and third harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority hydrogen heating scenario. While hints of improved RF heating efficiency as a function of the plasma temperature and plasma dilution (with 4 He) were confirmed in the H majority case, the 3 He concentration was the main handle on the heating efficiency in the second harmonic 3 He heating scenario.

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Section: Experimental Set-upmentioning

confidence: 99%

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Lerche¹,

Eester²,

Johnson³

et al. 2012

Plasma Phys. Control. Fusion

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“…JET is equipped with diagnostics that allow pinning down the temperature profiles with sufficient spatial and temporal resolution to yield meaningful results about where the externally launched waves transfer their energy to the plasma. The ion temperature profile is obtained via charge exchange diagnostics [31], while the electron temperature profile is estimated from electron cyclotron emission measurements [32].…”

Section: Development Of Icrf Heating Schemes For Iter's Non-active Phasementioning

confidence: 99%

Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments

Lerche¹,

Versloot

2011

Plasma Phys. Control. Fusion

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In the past years, one of the focal points of the JET experimental programme was on ion-cyclotron resonance heating (ICRH) studies in view of the design and exploitation of the ICRH system being developed for ITER. In this brief review, some of the main achievements obtained in JET in this field during the last 5 years will be summarized. The results reported here include important 18 See the appendix of Romanelli F et al 2010 Proc. 23rd IAEA Fusion Energy Conf. 2010. aspects of a more engineering nature, such as (i) the appropriate design of the RF feeding circuits for optimal load resilient operation and (ii) the test of a compact high-power density antenna array, as well as RF physics oriented studies aiming at refining the numerical models used for predicting the performance of the ICRH system in ITER. The latter include (i) experiments designed for improving the modelling of the antenna coupling resistance under various plasma conditions and (ii) the assessment of the heating performance of ICRH scenarios to be used in the non-active operation phase of ITER.

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“…C q+ ) in the plasma and injected fast neutral atoms, like e.g. H, He, or Li, to measure ion densities (von Hellermann et al 1990, Schorn et al 1991, Mandl et al 1993, temperatures (von Hellermann et al 1990, Schorn et al 1992, Mandl et al 1993, velocities of plasma rotation, and Z eff , the effective charge of the plasma (Isler 1994, Wolfrum et al 1993, Boileau et al 1989.…”

Section: Introductionmentioning

confidence: 99%

Charge exchange in Be⁴⁺–H(n= 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations

Igenbergs¹,

Schweinzer²,

Aumayr³

2009

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. Charge exchange in Be4+ -H(n = 1, 2) collisions was studied using the atomic-orbital close-coupling formalism in its impact parameter description and applying electron translational factors. Calculations were carried out in the energy range of 1 − 750 keV/amu with fully stripped beryllium ions impacting on atomic hydrogen in its ground state (1s) and in the excited n = 2 states. An optimized description of both collision centres was determined by analyzing the convergence of the total cross sections and also by comparison with other theoretical approaches. This optimized description consists of up to 170 basis states involving hydrogen-like states and pseudostates. We present total, n-resolved as well as n -resolved cross sections. The latter are needed to evaluate the emission cross sections in two limiting collisional plasma environments, i.e. single-collisional and multi-collisional. The calculated emission cross sections are compared with experimental data from the fusion experiment JET. Taking the experimental environment and certain characteristics of the theoretical methods into account, the agreement can be considered to be quite good.

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Visible charge exchange spectroscopy at JET

Cited by 81 publications

References 9 publications

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments

Charge exchange in Be⁴⁺–H(n= 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations

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Visible charge exchange spectroscopy at JET

Cited by 81 publications

References 9 publications

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Experimental investigation of ion cyclotron range of frequencies heating scenarios for ITER's half-field hydrogen phase performed in JET

Optimizing ion-cyclotron resonance frequency heating for ITER: dedicated JET experiments

Charge exchange in Be4+–H(n= 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations

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Charge exchange in Be⁴⁺–H(n= 1, 2) collisions studied systematically by atomic-orbital close-coupling calculations