Neutral particle emission in JET during radiofrequency heating experiments

Giannella, R.; Zanza, V.; Barbato, Emanuele; Bracco, G.; Corti, S.; Gambier, D.J.

doi:10.1088/0029-5515/28/2/002

Cited by 8 publications

(4 citation statements)

References 18 publications

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“…Radial profiles of charge exchange signals on JET [19] indicate that the power profile is fairly peaked, as theoretically predicted. It may be possible to explain the difference between the JET results and the broad charge exchange profiles observed on PLT by even stronger focusing of the RF power in the larger JET device and better fast ion confinement in JET's higher plasma current and lower ripple.…”

Section: Discussionsupporting

confidence: 78%

Measurements of energetic helium-3 minority distributions during ion cyclotron radiofrequency heating in the princeton Large Torus

1988

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Ion cyclotron radiofrequency heating experiments were performed with a 3 He minority ion species in a *He majority plasma in the Princeton Large Torus. The energetic 3 He ion 'tail' was measured directly with a charge exchange neutral analyser for the first time. Comparisons with bounce averaged quasi-linear calculations suggest a modestly peaked radiofrequency power deposition profile. The double charge exchange process ^e"* + 'fae 0 -> 3 He° + 4 He + * demonstrated in these measurements may be useful as part of an alpha particle diagnostic in a fusion reactor experiment.

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Section: Discussionsupporting

confidence: 78%

Measurements of energetic helium-3 minority distributions during ion cyclotron radiofrequency heating in the princeton Large Torus

1988

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“…The case of indirect electron heating raises further questions. This has been discussed in a previous paper [11], where it is shown that during absorption of the ICRF power by minority ions an energetic tail develops, and the high energy part of the tail responds linearly to the modulation if the averaged ICRF power is large compared to the modulation amplitude. Furthermore, for high ICRF power density [12], the dominant Coulomb collisions of minority ions are with electrons.…”

Section: Radius (M)mentioning

confidence: 86%

“…The minority hydrogen tail is monitored by the neutral particle analyser. A set of five analysers scan the plasma cross-section [11]. Only channels viewing the plasma centre exhibit an increase in the neutral flux (Fig.…”

Section: Icrf Modulation In D(h) Plasmas: Correlation With Sawtooth A...mentioning

confidence: 99%

ICRF power deposition profile and determination of the electron thermal diffusivity by modulation experiments in JET

Gambier¹,

Evrard²,

Adam³

et al. 1990

Nucl. Fusion

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The power deposition profile in the ion cyclotron range of frequencies (ICRF) has been investigated experimentally in JET by means of a square wave modulated RF perturbation. The study has been conducted in D(H) and D(3He) plasmas for two heating scenarios. In D(3He) plasmas and for central heating in a scenario where mode conversion to Bernstein waves is accessible, the direct power deposition profile on electrons has been derived. It accounts for 15% of the total coupled power and extends over 25% of the minor radius. Outside the RF power deposition zone, the electron thermal diffusivity χe inside the inversion radius surface (ri) can be estimated through observation of the diffusive electronic transport. In discharges without monster sawteeth and for a low central temperature gradient (∇Te(r ≤ ri) ≤ ∇Te(r ≥ ri) ≈ 5 keV·m−1) the value obtained is small (≈ 0.24 ± 0.05 m2·s−1), typically ten times ower than χe values deduced from heat pulse propagation in similar discharges at radii larger than the inversion radius. For the D(H) minority heating scheme, a large fraction of the ICRF modulated power is absorbed by minority ions, and the minority tail is modulated with a characteristic ion-electron (i–e) slowing-down time. In this scheme, electron heating occurs only through collisions with the minority ion tail and no modulation of the electron temperature is observed in sawtoothing discharges. This is interpreted as a consequence of the long i–e equipartition time, acting as an integrator for the modulated ICRF signal. Finally, a correlation between the time of the sawtooth crash and the periodic turn-off of the ICRF power is found and its consequence for modulation experiments is reviewed.

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“…To derive n a (r), the neutral transport was modelled by a numerical code, with the condition that the computed energy dependent neutral flux at the plasma edge should fit experimental values (see Ref. [17]).…”

Section: Profile Constraint For the Frascati Tokamakmentioning

confidence: 99%

The poloidal Ohm's law and a profile constraint in tokamaks

Segrè

Zanza

1991

Nucl. Fusion

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Explicit use of the poloidal Ohm's law, together with the radial plasma velocity (obtained from the distribution of plasma sources), leads to a very general constraint on the possible radial profiles of plasma density and temperature. The constraint does not require any ad hoc assumption; it can place severe restrictions on the allowed profiles and is independent of energy and particle transport; also, it may be the underlying principle of profile consistency. The constraint is discussed in the framework of neoclassical theory, using results from the Frascati tokamak.

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Neutral particle emission in JET during radiofrequency heating experiments

Cited by 8 publications

References 18 publications

Measurements of energetic helium-3 minority distributions during ion cyclotron radiofrequency heating in the princeton Large Torus

Measurements of energetic helium-3 minority distributions during ion cyclotron radiofrequency heating in the princeton Large Torus

ICRF power deposition profile and determination of the electron thermal diffusivity by modulation experiments in JET

The poloidal Ohm's law and a profile constraint in tokamaks

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